RF communications circuitry, which includes a first RF filter structure and control circuitry, is disclosed. The first RF filter structure includes a pair of weakly coupled resonators and a first tunable RF filter. The control circuitry provides a first filter control signal. The first tunable RF filter receives and filters an upstream RF signal to provide a first filtered RF signal, such that a center frequency of the first tunable RF filter is based on the first filter control signal.

FIELD OF THE DISCLOSURE

Embodiments of the present disclosure relate to radio frequency (RF) communications systems, which may include RF front-end circuitry, RF transceiver circuitry, RF amplifiers, direct current (DC)-DC converters, RF filters, RF antennas, RF switches, RF combiners, RF splitters, the like, or any combination thereof.

BACKGROUND

As wireless communications technologies evolve, wireless communications systems become increasingly sophisticated. As such, wireless communications protocols continue to expand and change to take advantage of the technological evolution. As a result, to maximize flexibility, many wireless communications devices must be capable of supporting any number of wireless communications protocols, each of which may have certain performance requirements, such as specific out-of-band emissions requirements, linearity requirements, or the like. Further, portable wireless communications devices are typically battery powered and need to be relatively small, and have low cost. As such, to minimize size, cost, and power consumption, RF circuitry in such a device needs to be as simple, small, flexible, and efficient as is practical. Thus, there is a need for RF circuitry in a communications device that is low cost, small, simple, flexible, and efficient.

SUMMARY

RF communications circuitry, which includes a first RF filter structure and control circuitry, is disclosed according to one embodiment of the present disclosure. The first RF filter structure includes a pair of weakly coupled resonators and a first tunable RF filter. The control circuitry provides a first filter control signal. The first tunable RF filter receives and filters an upstream RF signal to provide a first filtered RF signal, such that a center frequency of the first tunable RF filter is based on the first filter control signal.

In one embodiment of the RF communications circuitry, the first tunable RF filter is a first tunable RF receive filter, which is used to measure and profile an RF communications band by identifying active signals in the RF communications band. The profile is used to develop a measurement-based RF spectrum profile of the RF communications band. The active signals may be blocking signals in some RF communications systems and desired signals in other RF communications systems. The measurement-based RF spectrum profile may be used to help reject the blocking signals and accept the desired signals.

In one embodiment of the RF communications circuitry, the first tunable RF receive filter is used in either a normal operating mode or a profiling mode. In the profiling mode, the first tunable RF receive filter is used, as described above, in the development of the measurement-based RF spectrum profile. In the normal operating mode, the first tunable RF receive filter is used to receive and filter normal RF communications signals. As such, the center frequency of the first tunable RF receive filter may be adjusted based on the measurement-based RF spectrum profile to balance rejection of blocking signals and acceptance of desired signals.

In one embodiment of the first tunable RF receive filter, the first tunable RF receive filter is a reconfigurable tunable RF filter, such that a shape of a transfer function of the first tunable receive RF filter is reconfigurable. As such, a frequency response of the first tunable RF receive filter may be adjusted based on the measurement-based RF spectrum profile to further balance rejection of the blocking signals and acceptance of the desired signals.

DETAILED DESCRIPTION

RF communications circuitry, which includes a first RF filter structure, is disclosed according to a first embodiment of the present disclosure. The first RF filter structure includes a first tunable RF filter path and a second tunable RF filter path. The first tunable RF filter path includes a pair of weakly coupled resonators. Additionally, a first filter parameter of the first tunable RF filter path is tuned based on a first filter control signal. A first filter parameter of the second tunable RF filter path is tuned based on a second filter control signal.

In one embodiment of the first RF filter structure, the first tunable RF filter path is directly coupled between a first common connection node and a first connection node. The second tunable RF filter path is directly coupled between a second connection node and the first common connection node.

In one embodiment of the RF communications system, the first tunable RF filter path and the second tunable RF filter path do not significantly load one another at frequencies of interest. As such, by directly coupling the first tunable RF filter path and the second tunable RF filter path to the first common connection node; front-end RF switching elements may be avoided, thereby reducing cost, size, and non-linearity; and increasing efficiency and flexibility of the RF communications system. In one embodiment of the RF communications system, the first common connection node is coupled to an antenna.

Embodiments of the RF communications system include frequency division duplex (FDD) applications, time division duplex (TDD) applications, carrier-aggregation (CA) applications, multiple antenna applications, MIMO applications, hybrid applications, applications supporting multiple communications bands, the like, or any combination thereof.

FIG. 1shows traditional communications circuitry10according to the prior art. The traditional communications circuitry10illustrated inFIG. 1is a time-division duplex (TDD) system, which is capable of transmitting and receiving RF signals, but not simultaneously. Such a system may also be called a half-duplex system. Additionally, the traditional communications circuitry10may be used as a simplex system, which is a system that only transmits RF signals or only receives RF signals. Traditional communications systems often use fixed frequency filters. As a result, to cover multiple communications bands, switching elements are needed to select between different signal paths.

The traditional communications circuitry10includes traditional RF system control circuitry12, traditional RF front-end circuitry14, and a first RF antenna16. The traditional RF front-end circuitry14includes traditional RF front-end control circuitry18, first traditional antenna matching circuitry20, first traditional RF receive circuitry22, first traditional RF transmit circuitry24, a first traditional RF switch26, and a second traditional RF switch28. The first traditional RF switch26is coupled between the first traditional antenna matching circuitry20and the first traditional RF receive circuitry22. The second traditional RF switch28is coupled between the first traditional antenna matching circuitry20and the first traditional RF transmit circuitry24. The first RF antenna16is coupled to the first traditional antenna matching circuitry20. The first traditional antenna matching circuitry20provides at least partial impedance matching between the first RF antenna16and either the first traditional RF receive circuitry22or the first traditional RF transmit circuitry24.

The traditional RF system control circuitry12provides the necessary control functions needed to facilitate RF communications between the traditional communications circuitry10and other RF devices. The traditional RF system control circuitry12processes baseband signals needed for the RF communications. As such, the traditional RF system control circuitry12provides a first traditional upstream transmit signal TUT1to the first traditional RF transmit circuitry24. The first traditional upstream transmit signal TUT1may be a baseband transmit signal, an intermediate frequency (IF) transmit signal, or an RF transmit signal. Conversely, the traditional RF system control circuitry12receives a first traditional downstream receive signal TDR1from the first traditional RF receive circuitry22. The first traditional downstream receive signal TDR1may be a baseband receive signal, an IF receive signal, or an RF receive signal.

The traditional RF system control circuitry12provides a traditional front-end control signal TFEC to the traditional RF front-end control circuitry18. The traditional RF front-end control circuitry18provides a first traditional switch control signal TCS1and a second traditional switch control signal TCS2to the first traditional RF switch26and the second traditional RF switch28, respectively, based on the traditional front-end control signal TFEC. As such, the traditional RF system control circuitry12controls the first traditional RF switch26and the second traditional RF switch28via the traditional front-end control signal TFEC. The first traditional RF switch26is in one of an ON state and an OFF state based on the first traditional switch control signal TCS1. The second traditional RF switch28is in one of an ON state and an OFF state based on the second traditional switch control signal TCS2.

Half-duplex operation of the traditional communications circuitry10is accomplished using the first traditional RF switch26and the second traditional RF switch28. When the traditional communications circuitry10is transmitting RF signals via the first RF antenna16, the first traditional RF switch26is in the OFF state and the second traditional RF switch28is in the ON state. As such, the first traditional antenna matching circuitry20is electrically isolated from the first traditional RF receive circuitry22and the first traditional antenna matching circuitry20is electrically coupled to the first traditional RF transmit circuitry24. In this regard, the traditional RF system control circuitry12provides the first traditional upstream transmit signal TUT1to the first traditional RF transmit circuitry24, which provides a traditional transmit signal TTX to the first RF antenna16via the second traditional RF switch28and the first traditional antenna matching circuitry20based on the first traditional upstream transmit signal TUT1.

When the traditional communications circuitry10is receiving RF signals via the first RF antenna16, the first traditional RF switch26is in the ON state and the second traditional RF switch28is in the OFF state. As such, the first traditional antenna matching circuitry20is isolated from the first traditional RF transmit circuitry24and the first traditional antenna matching circuitry20is electrically coupled to the first traditional RF receive circuitry22. In this regard, the first traditional antenna matching circuitry20receives the RF signals from the first RF antenna16and forwards the RF signals via the first traditional RF switch26to the first traditional RF receive circuitry22. The first traditional RF switch26provides a traditional receive signal TRX to the first traditional RF receive circuitry22, which provides a first traditional downstream receive signal TDR1to the traditional RF system control circuitry12based on the traditional receive signal TRX.

Since the traditional communications circuitry10illustrated inFIG. 1is a half-duplex system, during operation, the first traditional RF switch26and the second traditional RF switch28are not simultaneously in the ON state. Therefore, the first traditional RF receive circuitry22and the first traditional RF transmit circuitry24are isolated from one another. As such, the first traditional RF receive circuitry22and the first traditional RF transmit circuitry24are prevented from interfering with one another.

FIG. 2shows the traditional communications circuitry10according to the prior art. The traditional communications circuitry10illustrated inFIG. 2is similar to the traditional communications circuitry10illustrated inFIG. 1, except in the traditional communications circuitry10illustrated inFIG. 2, the traditional RF front-end control circuitry18, the first traditional RF switch26, and the second traditional RF switch28are omitted, and the traditional RF front-end circuitry14further includes a first traditional RF duplexer30. The first traditional RF duplexer30is coupled between the first traditional antenna matching circuitry20and the first traditional RF receive circuitry22, and is further coupled between the first traditional antenna matching circuitry20and the first traditional RF transmit circuitry24.

The traditional communications circuitry10illustrated inFIG. 2may be used as a TDD system or a simplex system. However, the traditional communications circuitry10illustrated inFIG. 2may also be used as a frequency-division duplex (FDD) system, which is capable of transmitting and receiving RF signals simultaneously. Such a system may also be called a full-duplex system.

When the traditional communications circuitry10is transmitting RF signals via the first RF antenna16, the traditional RF system control circuitry12provides the first traditional upstream transmit signal TUT1to the first traditional RF transmit circuitry24, which provides the traditional transmit signal TTX to the first RF antenna16via first traditional RF duplexer30based on the first traditional upstream transmit signal TUT1.

When the traditional communications circuitry10is receiving RF signals via the first RF antenna16, the first traditional antenna matching circuitry20receives the RF signals from the first RF antenna16and forwards the RF signals via the first traditional RF duplexer30to the first traditional RF receive circuitry22. As such, the first traditional RF duplexer30provides the traditional receive signal TRX to the first traditional RF receive circuitry22, which provides the first traditional downstream receive signal TDR1to the traditional RF system control circuitry12based on the traditional receive signal TRX.

The first traditional RF duplexer30provides filtering, such that the first traditional RF receive circuitry22and the first traditional RF transmit circuitry24are substantially isolated from one another. As such, the first traditional RF receive circuitry22and the first traditional RF transmit circuitry24are prevented from interfering with one another. Traditional FDD systems using duplexers with high rejection ratios have a fixed frequency transfer. Covering multiple communications bands requires multiple duplexers and switches to route RF signals through appropriate signal paths.

FIG. 3shows the traditional communications circuitry10according to the prior art. The traditional communications circuitry10illustrated inFIG. 3is a carrier aggregation (CA) based system, which is capable of transmitting or receiving multiple simultaneous transmit signals or multiple simultaneous receive signals, respectively, or both. Each of the simultaneous transmit signals is in a frequency band that is different from each frequency band of a balance of the simultaneous transmit signals. Similarly, each of the simultaneous receive signals is in a frequency band that is different from each frequency band of a balance of the simultaneous receive signals. The traditional communications circuitry10may operate as a simplex system, a half-duplex system, or a full-duplex system.

The traditional communications circuitry10includes the traditional RF system control circuitry12, the traditional RF front-end circuitry14, the first RF antenna16, and a second RF antenna32. The traditional RF front-end circuitry14includes the first traditional antenna matching circuitry20, the first traditional RF receive circuitry22, the first traditional RF transmit circuitry24, the first traditional RF duplexer30, first traditional antenna switching circuitry34, a second traditional RF duplexer36, a third traditional RF duplexer38, second traditional antenna matching circuitry40, second traditional antenna switching circuitry42, a fourth traditional RF duplexer44, a fifth traditional RF duplexer46, a sixth traditional RF duplexer48, second traditional RF receive circuitry50, and second traditional RF transmit circuitry52. Traditional CA systems use fixed frequency filters and diplexers, triplexers, or both to combine signal paths, which increases complexity. Alternatively, additional switch paths may be used, but may degrade performance.

The first traditional antenna matching circuitry20is coupled between the first RF antenna16and the first traditional antenna switching circuitry34. The second traditional antenna matching circuitry40is coupled between the second RF antenna32and the second traditional antenna switching circuitry42. The first traditional RF duplexer30is coupled between the first traditional antenna switching circuitry34and the first traditional RF receive circuitry22, and is further coupled between the first traditional antenna switching circuitry34and the first traditional RF transmit circuitry24. The second traditional RF duplexer36is coupled between the first traditional antenna switching circuitry34and the first traditional RF receive circuitry22, and is further coupled between the first traditional antenna switching circuitry34and the first traditional RF transmit circuitry24. The third traditional RF duplexer38is coupled between the first traditional antenna switching circuitry34and the first traditional RF receive circuitry22, and is further coupled between the first traditional antenna switching circuitry34and the first traditional RF transmit circuitry24.

The fourth traditional RF duplexer44is coupled between the second traditional antenna switching circuitry42and the second traditional RF receive circuitry50, and is further coupled between the second traditional antenna switching circuitry42and the second traditional RF transmit circuitry52. The fifth traditional RF duplexer46is coupled between the second traditional antenna switching circuitry42and the second traditional RF receive circuitry50, and is further coupled between the second traditional antenna switching circuitry42and the second traditional RF transmit circuitry52. The sixth traditional RF duplexer48is coupled between the second traditional antenna switching circuitry42and the second traditional RF receive circuitry50, and is further coupled between the second traditional antenna switching circuitry42and the second traditional RF transmit circuitry52.

The first traditional RF duplexer30is associated with a first aggregated receive band, a first aggregated transmit band, or both. The second traditional RF duplexer36is associated with a second aggregated receive band, a second aggregated transmit band, or both. The third traditional RF duplexer38is associated with a third aggregated receive band, a third aggregated transmit band, or both. The fourth traditional RF duplexer44is associated with a fourth aggregated receive band, a fourth aggregated transmit band, or both. The fifth traditional RF duplexer46is associated with a fifth aggregated receive band, a fifth aggregated transmit band, or both. The sixth traditional RF duplexer48is associated with a sixth aggregated receive band, a sixth aggregated transmit band, or both.

The first traditional antenna switching circuitry34couples a selected one of the first traditional RF duplexer30, the second traditional RF duplexer36, and the third traditional RF duplexer38to the first traditional antenna matching circuitry20. Therefore, the first RF antenna16is associated with a selected one of the first aggregated receive band, the second aggregated receive band, and the third aggregated receive band; with a selected one of the first aggregated transmit band, the second aggregated transmit band, and the third aggregated transmit band; or both.

Similarly, the second traditional antenna switching circuitry42couples a selected one of the fourth traditional RF duplexer44, the fifth traditional RF duplexer46, and the sixth traditional RF duplexer48to the second traditional antenna matching circuitry40. Therefore, the second RF antenna32is associated with a selected one of the fourth aggregated receive band, the fifth aggregated receive band, and the sixth aggregated receive band; with a selected one of the fourth aggregated transmit band, the fifth aggregated transmit band, and the sixth aggregated transmit band; or both.

During transmit CA, the traditional RF system control circuitry12provides the first traditional upstream transmit signal TUT1to the first traditional RF transmit circuitry24, which forwards the first traditional upstream transmit signal TUT1to the first RF antenna16for transmission via the selected one of the first traditional RF duplexer30, the second traditional RF duplexer36, and the third traditional RF duplexer38; via the first traditional antenna switching circuitry34; and via the first traditional antenna matching circuitry20.

Additionally, during transmit CA, the traditional RF system control circuitry12provides a second traditional upstream transmit signal TUT2to the second traditional RF transmit circuitry52, which forwards the second traditional upstream transmit signal TUT2to the second RF antenna32for transmission via the selected one of the fourth traditional RF duplexer44, the fifth traditional RF duplexer46, and the sixth traditional RF duplexer48; via the second traditional antenna switching circuitry42; and via the second traditional antenna matching circuitry40.

During receive CA, the first RF antenna16forwards a received RF signal to the first traditional RF receive circuitry22via the first traditional antenna matching circuitry20, the first traditional antenna switching circuitry34, and the selected one of the first traditional RF duplexer30, the second traditional RF duplexer36, and the third traditional RF duplexer38. The first traditional RF receive circuitry22provides the first traditional downstream receive signal TDR1to the traditional RF system control circuitry12based on the received RF signal.

Additionally, during receive CA, the second RF antenna32forwards a received RF signal to the second traditional RF receive circuitry50via the second traditional antenna matching circuitry40, the second traditional antenna switching circuitry42, and the selected one of the fourth traditional RF duplexer44, the fifth traditional RF duplexer46, and the sixth traditional RF duplexer48. The second traditional RF receive circuitry50provides a second traditional downstream receive signal TDR2to the traditional RF system control circuitry12based on the received RF signal.

Since only the selected one of the first traditional RF duplexer30, the second traditional RF duplexer36, and the third traditional RF duplexer38is coupled to the first traditional antenna matching circuitry20; the first traditional antenna switching circuitry34isolates each of the first traditional RF duplexer30, the second traditional RF duplexer36, and the third traditional RF duplexer38from one another; and prevents each of the first traditional RF duplexer30, the second traditional RF duplexer36, and the third traditional RF duplexer38from interfering with one another.

Similarly, since only the selected one of the fourth traditional RF duplexer44, the fifth traditional RF duplexer46, and the sixth traditional RF duplexer48is coupled to the second traditional antenna matching circuitry40; the second traditional antenna matching circuitry40isolates each of the fourth traditional RF duplexer44, the fifth traditional RF duplexer46, and the sixth traditional RF duplexer48from one another; and prevents each of the fourth traditional RF duplexer44, the fifth traditional RF duplexer46, and the sixth traditional RF duplexer48from interfering with one another.

FIG. 4shows RF communications circuitry54according to one embodiment of the RF communications circuitry54. The RF communications circuitry54includes RF system control circuitry56, RF front-end circuitry58, and the first RF antenna16. The RF front-end circuitry58includes a first RF filter structure60, RF receive circuitry62, and RF transmit circuitry64. The first RF filter structure60includes a first tunable RF filter path66and a second tunable RF filter path68. Additionally, the first RF filter structure60has a first connection node70, a second connection node72, and a first common connection node74. In one embodiment of the RF system control circuitry56, the RF system control circuitry56is an RF transceiver. In one embodiment of the first tunable RF filter path66, the first tunable RF filter path66includes a pair of weakly coupled resonators R(1,1), R(1,2) (FIG. 22). As such, in one embodiment of the first RF filter structure60, the RF filter structure60includes the pair of weakly coupled resonators R(1,1), R(1,2) (FIG. 21).

In alternate embodiments of the first RF filter structure60, any or all of the first connection node70, the second connection node72, and the first common connection node74are external to the first RF filter structure60. In one embodiment of the first tunable RF filter path66, the first tunable RF filter path66includes a first pair (not shown) of weakly coupled resonators. In one embodiment of the second tunable RF filter path68, the second tunable RF filter path68includes a second pair (not shown) of weakly coupled resonators.

In one embodiment of the first RF filter structure60, the first tunable RF filter path66is directly coupled between the first common connection node74and the first connection node70, the second tunable RF filter path68is directly coupled between the second connection node72and the first common connection node74, and the first RF antenna16is directly coupled to the first common connection node74. In another embodiment of the RF communications circuitry54, the first RF antenna16is omitted. Additionally, the RF receive circuitry62is coupled between the first connection node70and the RF system control circuitry56, and the RF transmit circuitry64is coupled between the second connection node72and the RF system control circuitry56.

In one embodiment of the RF communications circuitry54, the first tunable RF filter path66is a first RF receive filter, such that the first RF antenna16forwards a received RF signal via the first common connection node74to provide a first upstream RF receive signal RU1to the first tunable RF filter path66, which receives and filters the first upstream RF receive signal RU1to provide a first filtered RF receive signal RF1to the RF receive circuitry62. The RF receive circuitry62may include down-conversion circuitry, amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof. The RF receive circuitry62processes the first filtered RF receive signal RF1to provide a first receive signal RX1to the RF system control circuitry56.

In one embodiment of the RF communications circuitry54, the second tunable RF filter path68is a first RF transmit filter, such that the RF system control circuitry56provides a first transmit signal TX1to the RF transmit circuitry64, which processes the first transmit signal TX1to provide a first upstream RF transmit signal TU1to the second tunable RF filter path68. The RF transmit circuitry64may include up-conversion circuitry, amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof. The second tunable RF filter path68receives and filters the first upstream RF transmit signal TU1to provide a first filtered RF transmit signal TF1, which is transmitted via the first common connection node74by the first RF antenna16.

The RF system control circuitry56provides a first filter control signal FCS1to the first tunable RF filter path66and provides a second filter control signal FCS2to the second tunable RF filter path68. As such, in one embodiment of the RF communications circuitry54, the RF system control circuitry56tunes a first filter parameter of the first tunable RF filter path66using the first filter control signal FCS1. Additionally, the RF system control circuitry56tunes a first filter parameter of the second tunable RF filter path68using the second filter control signal FCS2.

In one embodiment of the RF communications circuitry54, the first tunable RF filter path66and the second tunable RF filter path68do not significantly load one another at frequencies of interest. As such, by directly coupling the first tunable RF filter path66and the second tunable RF filter path68to the first common connection node74; front-end RF switching elements may be avoided, thereby reducing cost, size, and non-linearity; and increasing efficiency and flexibility of the RF communications circuitry54. Since tunable RF filters can support multiple communications bands using a single signal path, they can simplify front-end architectures by eliminating switching and duplexing components.

In one embodiment of the RF communications circuitry54, the RF communications circuitry54is used as an FDD communications system, such that the first upstream RF receive signal RU1and the first filtered RF transmit signal TF1are full-duplex signals. In an alternate embodiments of the RF communications circuitry54, the RF communications circuitry54is used as a TDD communications system, such that the first upstream RF receive signal RU1and the first filtered RF transmit signal TF1are half-duplex signals. In additional embodiments of the RF communications circuitry54, the RF communications circuitry54is used as a simplex communications system, such that the first upstream RF receive signal RU1is a simplex signal and the first filtered RF transmit signal TF1is not present. In other embodiments of the RF communications circuitry54, the RF communications circuitry54is used as a simplex communications system, such that the first upstream RF receive signal RU1is not present and the first filtered RF transmit signal TF1is a simplex signal.

FIG. 5is a graph illustrating filtering characteristics of the first tunable RF filter path66and the second tunable RF filter path68illustrated inFIG. 4according to one embodiment of the first tunable RF filter path66and the second tunable RF filter path68. The first tunable RF filter path66is a first RF bandpass filter, which functions as the first RF receive filter, and the second tunable RF filter path68is a second RF bandpass filter, which functions as the first RF transmit filter. A bandwidth76of the first RF bandpass filter, a center frequency78of the first RF bandpass filter, a bandwidth80of the second RF bandpass filter, a center frequency82of the second RF bandpass filter, a frequency84of the first upstream RF receive signal RU1(FIG. 4), and a frequency86of the first filtered RF transmit signal TF1(FIG. 4) are shown. Operation of the first RF bandpass filter and the second RF bandpass filter is such that the first RF bandpass filter and the second RF bandpass filter do not significantly interfere with one another. In this regard, the bandwidth76of the first RF bandpass filter does not overlap the bandwidth80of the second RF bandpass filter.

In one embodiment of the first RF receive filter and the first RF transmit filter, the first RF receive filter and the first RF transmit filter in combination function as an RF duplexer. As such, a duplex frequency88of the RF duplexer is about equal to a difference between the frequency84of the first upstream RF receive signal RU1(FIG. 4) and the frequency86of the first filtered RF transmit signal TF1(FIG. 4).

In one embodiment of the first tunable RF filter path66, the first filter parameter of the first tunable RF filter path66is tunable based on the first filter control signal FCS1. In an alternate embodiment of the first tunable RF filter path66, both the first filter parameter of the first tunable RF filter path66and a second filter parameter of the first tunable RF filter path66are tunable based on the first filter control signal FCS1. Similarly, in one embodiment of the second tunable RF filter path68, the first filter parameter of the second tunable RF filter path68is tunable based on the second filter control signal FCS2. In an alternate embodiment of the second tunable RF filter path68, both the first filter parameter of the second tunable RF filter path68and a second filter parameter of the second tunable RF filter path68are tunable based on the second filter control signal FCS2.

The first filter parameter of the first tunable RF filter path66is the center frequency78of the first RF bandpass filter. The second filter parameter of the first tunable RF filter path66is the bandwidth76of the first RF bandpass filter. The first filter parameter of the second tunable RF filter path68is the center frequency82of the second RF bandpass filter. The second filter parameter of the second tunable RF filter path68is the bandwidth80of the second RF bandpass filter.

FIGS. 6A and 6Bare graphs illustrating filtering characteristics of the first tunable RF filter path66and the second tunable RF filter path68, respectively, illustrated inFIG. 4according to an alternate embodiment of the first tunable RF filter path66and the second tunable RF filter path68, respectively. The first tunable RF filter path66is an RF lowpass filter and the second tunable RF filter path68is an RF highpass filter.FIG. 6Ashows a frequency response curve90of the RF lowpass filter andFIG. 6Bshows a frequency response curve92of the RF highpass filter. AdditionallyFIG. 6Ashows a break frequency94of the RF lowpass filter andFIG. 6Bshows a break frequency96of the RF highpass filter. BothFIGS. 6A and 6Bshow the frequency84of the first upstream RF receive signal RU1(FIG. 4), the frequency86of the first filtered RF transmit signal TF1(FIG. 4), and the duplex frequency88of the RF duplexer for clarification. However, the RF lowpass filter and the RF highpass filter in combination function as an RF diplexer. The first filter parameter of the first tunable RF filter path66is the break frequency94of the RF lowpass filter. In one embodiment of the RF lowpass filter, the RF lowpass filter has bandpass filter characteristics. The first filter parameter of the second tunable RF filter path68is the break frequency96of the RF highpass filter. In one embodiment of the RF highpass filter, the RF highpass filter has bandpass filter characteristics. In one embodiment of the RF diplexer, the break frequency96of the RF highpass filter is about equal to the break frequency94of the RF lowpass filter.

FIG. 7shows the RF communications circuitry54according to one embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 7is similar to the RF communications circuitry54illustrated inFIG. 4, except in the RF front-end circuitry58illustrated inFIG. 7, the RF transmit circuitry64(FIG. 4) is omitted and the RF front-end circuitry58further includes RF front-end control circuitry98.

The RF system control circuitry56provides a front-end control signal FEC to the RF front-end control circuitry98. The RF front-end control circuitry98provides the first filter control signal FCS1and the second filter control signal FCS2based on the front-end control signal FEC. In the RF communications circuitry54illustrated inFIG. 4, the RF system control circuitry56provides the first filter control signal FCS1and the second filter control signal FCS2directly. In general, the RF communications circuitry54includes control circuitry, which may be either the RF system control circuitry56or the RF front-end control circuitry98, that provides the first filter control signal FCS1and the second filter control signal FCS2. As such, in one embodiment of the RF communications circuitry54, the control circuitry tunes a first filter parameter of the first tunable RF filter path66using the first filter control signal FCS1. Additionally, the control circuitry tunes a first filter parameter of the second tunable RF filter path68using the second filter control signal FCS2. In an additional embodiment of the RF communications circuitry54, the control circuitry further tunes a second filter parameter of the first tunable RF filter path66using the first filter control signal FCS1; and the control circuitry further tunes a second filter parameter of the second tunable RF filter path68using the second filter control signal FCS2.

In alternate embodiments of the first RF filter structure60, any or all of the first connection node70, the second connection node72, and the first common connection node74are external to the first RF filter structure60. In one embodiment of the first tunable RF filter path66, the first tunable RF filter path66includes a first pair (not shown) of weakly coupled resonators. In one embodiment of the second tunable RF filter path68, the second tunable RF filter path68includes a second pair (not shown) of weakly coupled resonators.

In one embodiment of the first RF filter structure60, the first tunable RF filter path66is directly coupled between the first common connection node74and the first connection node70, the second tunable RF filter path68is directly coupled between the second connection node72and the first common connection node74, and the first RF antenna16is directly coupled to the first common connection node74. In another embodiment of the RF communications circuitry54, the first RF antenna16is omitted. Additionally, the RF receive circuitry62is coupled between the first connection node70and the RF system control circuitry56, and the RF receive circuitry62is further coupled between the second connection node72and the RF system control circuitry56.

In one embodiment of the RF communications circuitry54, the first tunable RF filter path66is a first RF receive filter, such that the first RF antenna16forwards a first received RF signal via the first common connection node74to provide a first upstream RF receive signal RU1to the first tunable RF filter path66, which receives and filters the first upstream RF receive signal RU1to provide a first filtered RF receive signal RF1to the RF receive circuitry62. Additionally, the second tunable RF filter path68is a second RF receive filter, such that the first RF antenna16forwards a second received RF signal via the first common connection node74to provide a second upstream RF receive signal RU2to the second tunable RF filter path68, which receives and filters the second upstream RF receive signal RU2to provide a second filtered RF receive signal RF2to the RF receive circuitry62.

The RF receive circuitry62may include down-conversion circuitry, amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof. The RF receive circuitry62processes the first filtered RF receive signal RF1to provide a first receive signal RX1to the RF system control circuitry56. Additionally, the RF receive circuitry62processes the second filtered RF receive signal RF2to provide a second receive signal RX2to the RF system control circuitry56.

In one embodiment of the RF communications circuitry54, the first tunable RF filter path66and the second tunable RF filter path68do not significantly load one another at frequencies of interest. As such, by directly coupling the first tunable RF filter path66and the second tunable RF filter path68to the first common connection node74; front-end RF switching elements may be avoided, thereby reducing cost, size, and non-linearity; and increasing efficiency and flexibility of the RF communications circuitry54.

In this regard, in one embodiment of the first tunable RF filter path66and the second tunable RF filter path68, each of the first tunable RF filter path66and the second tunable RF filter path68is a bandpass filter having a unique center frequency. As such, the first filter parameter of each of the first tunable RF filter path66and the second tunable RF filter path68is a unique center frequency.

In an alternate embodiment of the first tunable RF filter path66and the second tunable RF filter path68, one of the first tunable RF filter path66and the second tunable RF filter path68is a lowpass filter, and another of the first tunable RF filter path66and the second tunable RF filter path68is a highpass filter. As such, the first filter parameter of each of the first tunable RF filter path66and the second tunable RF filter path68is a break frequency.

In an additional embodiment of the first tunable RF filter path66and the second tunable RF filter path68, one of the first tunable RF filter path66and the second tunable RF filter path68is a lowpass filter, and another of the first tunable RF filter path66and the second tunable RF filter path68is a bandpass filter. As such, the first filter parameter of one of the first tunable RF filter path66and the second tunable RF filter path68is a center frequency, and the first filter parameter of another of the first tunable RF filter path66and the second tunable RF filter path68is a break frequency.

In an additional embodiment of the first tunable RF filter path66and the second tunable RF filter path68, one of the first tunable RF filter path66and the second tunable RF filter path68is a highpass filter, and another of the first tunable RF filter path66and the second tunable RF filter path68is a bandpass filter. As such, the first filter parameter of one of the first tunable RF filter path66and the second tunable RF filter path68is a center frequency, and the first filter parameter of another of the first tunable RF filter path66and the second tunable RF filter path68is a break frequency.

In one embodiment of the RF communications circuitry54, the RF communications circuitry54is a receive only CA system, such that the first tunable RF filter path66, which is the first RF receive filter, and the second tunable RF filter path68, which is the second RF receive filter, simultaneously receive and filter the first upstream RF receive signal RU1and the second upstream RF receive signal RU2, respectively, via the first common connection node74. As such, the first RF filter structure60functions as a de-multiplexer. In this regard, each of the first upstream RF receive signal RU1and the second upstream RF receive signal RU2has a unique carrier frequency. Using receive CA may increase an effective receive bandwidth of the RF communications circuitry54.

In another embodiment of the RF communications circuitry54, the RF communications circuitry54is a receive only communications system, such that the first tunable RF filter path66, which is the first RF receive filter, and the second tunable RF filter path68, which is the second RF receive filter, do not simultaneously receive and filter the first upstream RF receive signal RU1and the second upstream RF receive signal RU2, respectively. As such, the first upstream RF receive signal RU1and the second upstream RF receive signal RU2are nonsimultaneous signals. Each of the first upstream RF receive signal RU1and the second upstream RF receive signal RU2may be associated with a unique RF communications band.

FIG. 8shows the RF communications circuitry54according to an alternate embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 8is similar to the RF communications circuitry54illustrated inFIG. 7, except in the RF front-end circuitry58illustrated inFIG. 8, the RF receive circuitry62is omitted and the RF transmit circuitry64is included.

The RF system control circuitry56provides the front-end control signal FEC to the RF front-end control circuitry98. The RF front-end control circuitry98provides the first filter control signal FCS1and the second filter control signal FCS2based on the front-end control signal FEC. In the RF communications circuitry54illustrated inFIG. 4, the RF system control circuitry56provides the first filter control signal FCS1and the second filter control signal FCS2directly. In general, the RF communications circuitry54includes control circuitry, which may be either the RF system control circuitry56or the RF front-end control circuitry98, that provides the first filter control signal FCS1and the second filter control signal FCS2. As such, in one embodiment of the RF communications circuitry54, the control circuitry tunes a first filter parameter of the first tunable RF filter path66using the first filter control signal FCS1. Additionally, the control circuitry tunes a first filter parameter of the second tunable RF filter path68using the second filter control signal FCS2. In an additional embodiment of the RF communications circuitry54, the control circuitry further tunes a second filter parameter of the first tunable RF filter path66using the first filter control signal FCS1; and the control circuitry further tunes a second filter parameter of the second tunable RF filter path68using the second filter control signal FCS2.

In alternate embodiments of the first RF filter structure60, any or all of the first connection node70, the second connection node72, and the first common connection node74are external to the first RF filter structure60. In one embodiment of the first tunable RF filter path66, the first tunable RF filter path66includes a first pair (not shown) of weakly coupled resonators. In one embodiment of the second tunable RF filter path68, the second tunable RF filter path68includes a second pair (not shown) of weakly coupled resonators.

In one embodiment of the first RF filter structure60, the first tunable RF filter path66is directly coupled between the first common connection node74and the first connection node70, the second tunable RF filter path68is directly coupled between the second connection node72and the first common connection node74, and the first RF antenna16is directly coupled to the first common connection node74. In another embodiment of the RF communications circuitry54, the first RF antenna16is omitted. Additionally, the RF transmit circuitry64is coupled between the first connection node70and the RF system control circuitry56, and the RF transmit circuitry64is further coupled between the second connection node72and the RF system control circuitry56.

In one embodiment of the RF communications circuitry54, the first tunable RF filter path66is a first RF transmit filter, such that the RF system control circuitry56provides the first transmit signal TX1to the RF transmit circuitry64, which processes the first transmit signal TX1to provide a first upstream RF transmit signal TU1to the first tunable RF filter path66. Similarly, the second tunable RF filter path68is a second RF transmit filter, such that the RF system control circuitry56provides a second transmit signal TX2to the RF transmit circuitry64, which processes the second transmit signal TX2to provide a second upstream RF transmit signal TU2to the second tunable RF filter path68.

The RF transmit circuitry64may include up-conversion circuitry, amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof. The first tunable RF filter path66receives and filters the first upstream RF transmit signal TU1to provide the first filtered RF transmit signal TF1, which is transmitted via the first common connection node74by the first RF antenna16. Similarly, the second tunable RF filter path68receives and filters the second upstream RF transmit signal TU2to provide a second filtered RF transmit signal TF2, which is transmitted via the first common connection node74by the first RF antenna16.

In one embodiment of the RF communications circuitry54, the first tunable RF filter path66and the second tunable RF filter path68do not significantly load one another at frequencies of interest. As such, by directly coupling the first tunable RF filter path66and the second tunable RF filter path68to the first common connection node74; front-end RF switching elements may be avoided, thereby reducing cost, size, and non-linearity; and increasing efficiency and flexibility of the RF communications circuitry54.

In this regard, in one embodiment of the first tunable RF filter path66and the second tunable RF filter path68, each of the first tunable RF filter path66and the second tunable RF filter path68is a bandpass filter having a unique center frequency. As such, the first filter parameter of each of the first tunable RF filter path66and the second tunable RF filter path68is a unique center frequency.

In an alternate embodiment of the first tunable RF filter path66and the second tunable RF filter path68, one of the first tunable RF filter path66and the second tunable RF filter path68is a lowpass filter, and another of the first tunable RF filter path66and the second tunable RF filter path68is a highpass filter. As such, the first filter parameter of each of the first tunable RF filter path66and the second tunable RF filter path68is a break frequency.

In an additional embodiment of the first tunable RF filter path66and the second tunable RF filter path68, one of the first tunable RF filter path66and the second tunable RF filter path68is a lowpass filter, and another of the first tunable RF filter path66and the second tunable RF filter path68is a bandpass filter. As such, the first filter parameter of one of the first tunable RF filter path66and the second tunable RF filter path68is a center frequency, and the first filter parameter of another of the first tunable RF filter path66and the second tunable RF filter path68is a break frequency.

In an additional embodiment of the first tunable RF filter path66and the second tunable RF filter path68, one of the first tunable RF filter path66and the second tunable RF filter path68is a highpass filter, and another of the first tunable RF filter path66and the second tunable RF filter path68is a bandpass filter. As such, the first filter parameter of one of the first tunable RF filter path66and the second tunable RF filter path68is a center frequency, and the first filter parameter of another of the first tunable RF filter path66and the second tunable RF filter path68is a break frequency.

In one embodiment of the RF communications circuitry54, the RF communications circuitry54is a transmit only CA system, such that the first tunable RF filter path66, which is the first RF transmit filter, and the second tunable RF filter path68, which is the second RF transmit filter, simultaneously receive and filter the first upstream RF transmit signal TU1and the second upstream RF transmit signal TU2, respectively, to simultaneously provide the first filtered RF transmit signal TF1and the second filtered RF transmit signal TF2, respectively, via the first common connection node74. As such, the first RF filter structure60functions as a multiplexer. In this regard, each of the first filtered RF transmit signal TF1and the second filtered RF transmit signal TF2has a unique carrier frequency. Using transmit CA may increase an effective transmit bandwidth of the RF communications circuitry54.

In another embodiment of the RF communications circuitry54, the RF communications circuitry54is a transmit only communications system, such that the first tunable RF filter path66, which is the first RF transmit filter, and the second tunable RF filter path68, which is the second RF transmit filter, do not simultaneously receive and filter the first upstream RF transmit signal TU1and the second upstream RF transmit signal TU2, respectively. As such, the first filtered RF transmit signal TF1and the second filtered RF transmit signal TF2are nonsimultaneous signals. Each of the first filtered RF transmit signal TF1and the second filtered RF transmit signal TF2may be associated with a unique RF communications band.

FIGS. 9A and 9Bare graphs illustrating filtering characteristics of the first tunable RF filter path66and the second tunable RF filter path68, respectively, illustrated inFIG. 8according to an additional embodiment of the first tunable RF filter path66and the second tunable RF filter path68, respectively.FIG. 9Ashows a frequency response curve100of the first tunable RF filter path66andFIG. 9Bshows a frequency response curve102of the second tunable RF filter path68. The first tunable RF filter path66and the second tunable RF filter path68are both bandpass filters having the frequency response curves100,102illustrated inFIGS. 9A and 9B, respectively. In this regard, the first tunable RF filter path66and the second tunable RF filter path68can be directly coupled to one another via the first common connection node74(FIG. 8) without interfering with one another.

FIGS. 10A and 10Bare graphs illustrating filtering characteristics of the first traditional RF duplexer30and the second traditional RF duplexer36, respectively, illustrated inFIG. 3according to the prior art.FIG. 10Ashows a frequency response curve104of the first traditional RF duplexer30andFIG. 10Bshows a frequency response curve106of the second traditional RF duplexer36. There is interference108between the frequency response curve104of the first traditional RF duplexer30and the frequency response curve106of the second traditional RF duplexer36as shown inFIGS. 10A and 10B. In this regard, the first traditional RF duplexer30and the second traditional RF duplexer36cannot be directly coupled to one another without interfering with one another. To avoid interference between different filters, traditional systems use RF switches to disconnect unused filters.

FIG. 11shows the RF communications circuitry54according to one embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 11is similar to the RF communications circuitry54illustrated inFIG. 8, except in the RF communications circuitry54illustrated inFIG. 11, the RF front-end circuitry58further includes the RF receive circuitry62and the first RF filter structure60further includes a third tunable RF filter path110and a fourth tunable RF filter path112. Additionally, the RF front-end circuitry58has the first connection node70, the second connection node72, the first common connection node74, a third connection node114and a fourth connection node116, such that all of the first connection node70, the second connection node72, the first common connection node74, the third connection node114and the fourth connection node116are external to the first RF filter structure60. In an alternate of the RF front-end circuitry58, any or all of the first connection node70, the second connection node72, the first common connection node74, a third connection node114and a fourth connection node116are internal to the first RF filter structure60.

The RF front-end control circuitry98further provides a third filter control signal FCS3to the third tunable RF filter path110and a fourth filter control signal FCS4to the fourth tunable RF filter path112based on the front-end control signal FEC. In one embodiment of the RF communications circuitry54, the control circuitry tunes a first filter parameter of the third tunable RF filter path110using the third filter control signal FCS3. Additionally, the control circuitry tunes a first filter parameter of the fourth tunable RF filter path112using the fourth filter control signal FCS4. In an additional embodiment of the RF communications circuitry54, the control circuitry further tunes a second filter parameter of the third tunable RF filter path110using the third filter control signal FCS3; and the control circuitry further tunes a second filter parameter of the fourth tunable RF filter path112using the fourth filter control signal FCS4.

In one embodiment of the third tunable RF filter path110, the third tunable RF filter path110includes a third pair (not shown) of weakly coupled resonators. In one embodiment of the fourth tunable RF filter path112, the fourth tunable RF filter path112includes a fourth pair (not shown) of weakly coupled resonators.

In one embodiment of the third tunable RF filter path110and the fourth tunable RF filter path112, the third tunable RF filter path110is directly coupled between the first common connection node74and the third connection node114, and the fourth tunable RF filter path112is directly coupled between the fourth connection node116and the first common connection node74. In another embodiment of the RF communications circuitry54, the first RF antenna16is omitted. Additionally, the RF receive circuitry62is coupled between the third connection node114and the RF system control circuitry56, and the RF receive circuitry62is further coupled between the fourth connection node116and the RF system control circuitry56.

In one embodiment of the RF communications circuitry54, the third tunable RF filter path110is the first RF receive filter, such that the first RF antenna16forwards a first received RF signal via the first common connection node74to provide the first upstream RF receive signal RU1to the third tunable RF filter path110, which receives and filters the first upstream RF receive signal RU1to provide the first filtered RF receive signal RF1to the RF receive circuitry62. Additionally, the fourth tunable RF filter path112is a second RF receive filter, such that the first RF antenna16forwards a second received RF signal via the first common connection node74to provide the second upstream RF receive signal RU2to the fourth tunable RF filter path112, which receives and filters the second upstream RF receive signal RU2to provide the second filtered RF receive signal RF2to the RF receive circuitry62.

The RF receive circuitry62may include down-conversion circuitry, amplification circuitry, power supply circuitry, filtering circuitry, switching circuitry, combining circuitry, splitting circuitry, dividing circuitry, clocking circuitry, the like, or any combination thereof. The RF receive circuitry62processes the first filtered RF receive signal RF1to provide the first receive signal RX1to the RF system control circuitry56. Additionally, the RF receive circuitry62processes the second filtered RF receive signal RF2to provide the second receive signal RX2to the RF system control circuitry56.

In one embodiment of the RF communications circuitry54, the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, and the fourth tunable RF filter path112do not significantly load one another at frequencies of interest. As such, by directly coupling the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, and the fourth tunable RF filter path112to the first common connection node74; front-end RF switching elements may be avoided, thereby reducing cost, size, and non-linearity; and increasing efficiency and flexibility of the RF communications circuitry54.

In this regard, in one embodiment of the third tunable RF filter path110and the fourth tunable RF filter path112, each of the third tunable RF filter path110and the fourth tunable RF filter path112is a bandpass filter having a unique center frequency. As such, the first filter parameter of each of the third tunable RF filter path110and the fourth tunable RF filter path112is a unique center frequency.

In an alternate embodiment of the third tunable RF filter path110and the fourth tunable RF filter path112, one of the third tunable RF filter path110and the fourth tunable RF filter path112is a lowpass filter, and another of the third tunable RF filter path110and the fourth tunable RF filter path112is a highpass filter. As such, the first filter parameter of each of the third tunable RF filter path110and the fourth tunable RF filter path112is a break frequency.

In an additional embodiment of the third tunable RF filter path110and the fourth tunable RF filter path112, one of the third tunable RF filter path110and the fourth tunable RF filter path112is a lowpass filter, and another of the third tunable RF filter path110and the fourth tunable RF filter path112is a bandpass filter. As such, the first filter parameter of one of the third tunable RF filter path110and the fourth tunable RF filter path112is a center frequency, and the first filter parameter of another of the third tunable RF filter path110and the fourth tunable RF filter path112is a break frequency.

In an additional embodiment of the third tunable RF filter path110and the fourth tunable RF filter path112, one of the third tunable RF filter path110and the fourth tunable RF filter path112is a highpass filter, and another of the third tunable RF filter path110and the fourth tunable RF filter path112is a bandpass filter. As such, the first filter parameter of one of the third tunable RF filter path110and the fourth tunable RF filter path112is a center frequency, and the first filter parameter of another of the third tunable RF filter path110and the fourth tunable RF filter path112is a break frequency.

In one embodiment of the RF communications circuitry54, the RF communications circuitry54is a CA system, such that the third tunable RF filter path110, which is the first RF receive filter, and the fourth tunable RF filter path112, which is the second RF receive filter, simultaneously receive and filter the first upstream RF receive signal RU1and the second upstream RF receive signal RU2, respectively, via the first common connection node74. As such, the first RF filter structure60functions as a de-multiplexer using the third tunable RF filter path110and the fourth tunable RF filter path112. In one embodiment of the first RF filter structure60, the first RF filter structure60further functions as a multiplexer using the first tunable RF filter path66and the second tunable RF filter path68. In this regard, each of the first upstream RF receive signal RU1and the second upstream RF receive signal RU2has a unique carrier frequency.

In another embodiment of the RF communications circuitry54, the RF communications circuitry54is a receive communications system, such that the third tunable RF filter path110, which is the first RF receive filter, and the fourth tunable RF filter path112, which is the second RF receive filter, do not simultaneously receive and filter the first upstream RF receive signal RU1and the second upstream RF receive signal RU2, respectively. As such, the first upstream RF receive signal RU1and the second upstream RF receive signal RU2are nonsimultaneous signals. Each of the first upstream RF receive signal RU1and the second upstream RF receive signal RU2may be associated with a unique RF communications band.

FIG. 12shows the RF communications circuitry54according to an alternate embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 12is similar to the RF communications circuitry54illustrated inFIG. 11, except the RF communications circuitry54illustrated inFIG. 12further includes the second RF antenna32. Additionally, the RF front-end circuitry58further includes a second common connection node118and a second RF filter structure120. The third tunable RF filter path110and the fourth tunable RF filter path112are included in the second RF filter structure120instead of being included in the first RF filter structure60. Instead of being coupled to the first common connection node74, the third tunable RF filter path110and the fourth tunable RF filter path112are coupled to the second common connection node118. In one embodiment of the third tunable RF filter path110and the fourth tunable RF filter path112, the third tunable RF filter path110and the fourth tunable RF filter path112are directly coupled to the second common connection node118. In one embodiment of the RF communications circuitry54, the second RF antenna32is coupled to the second common connection node118.

FIG. 13shows the RF communications circuitry54according to an additional embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 13is similar to the RF communications circuitry54illustrated inFIG. 12, except in the RF communications circuitry54illustrated inFIG. 13, the RF front-end control circuitry98provides a front-end status signal FES to the RF system control circuitry56. Additionally, the RF front-end control circuitry98provides a first calibration control signal CCS1and up to and including an NTHcalibration control signal CCSN to the first RF filter structure60. The RF front-end control circuitry98provides a PTHcalibration control signal CCSP and up to and including an XTHcalibration control signal CCSX to the second RF filter structure120. Details of the first RF filter structure60and the second RF filter structure120are not shown to simplifyFIG. 13.

The first RF filter structure60provides a first calibration status signal CSS1and up to and including a QTHcalibration status signal CSSQ to the RF front-end control circuitry98. The second RF filter structure120provides an RTHcalibration status signal CSSR and up to and including a YTHcalibration status signal CSSY to the RF front-end control circuitry98. In an alternate embodiment of the RF front-end circuitry58, any or all of the NTHcalibration control signal CCSN, the QTHcalibration status signal CSSQ, the XTHcalibration control signal CCSX, and the YTHcalibration status signal CSSY are omitted.

In one embodiment of the RF front-end circuitry58, the RF front-end circuitry58operates in one of a normal operating mode and a calibration mode. During the calibration mode, the RF front-end control circuitry98performs a calibration of the first RF filter structure60, the second RF filter structure120, or both. As such, the RF front-end control circuitry98provides any or all of the filter control signals FCS1, FCS2, FCS3, FCS4and any or all of the calibration control signals CCS1, CCSN, CCSP, CCSX needed for calibration. Further, the RF front-end control circuitry98receives any or all of the calibration status signals CSS1, CSSQ, CSSR, CSSY needed for calibration.

During the normal operating mode, the RF front-end control circuitry98provides any or all of the filter control signals FCS1, FCS2, FCS3, FCS4and any or all of the calibration control signals CCS1, CCSN, CCSP, CCSX needed for normal operation. Further, the RF front-end control circuitry98receives any or all of the calibration status signals CSS1, CSSQ, CSSR, CSSY needed for normal operation. Any or all of the calibration control signals CCS1, CCSN, CCSP, CCSX may be based on the front-end control signal FEC. The front-end status signal FES may be based on any or all of the calibration status signals CSS1, CSSQ, CSSR, CSSY. Further, during the normal operating mode, the RF front-end circuitry58processes signals as needed for normal operation. Other embodiments described in the present disclosure may be associated with normal operation.

The RF communications circuitry54illustrated inFIG. 13includes the first RF antenna16and the second RF antenna32. In general, the RF communications circuitry54is a multiple antenna system. A single-input single-output (SISO) antenna system is a system in which RF transmit signals may be transmitted from the first RF antenna16and RF receive signals may be received via the second RF antenna32. In one embodiment of the RF communications circuitry54, the antenna system in the RF communications circuitry54is a SISO antenna system, as illustrated inFIG. 13.

A single-input multiple-output (SIMO) antenna system is a system in which RF transmit signals may be simultaneously transmitted from the first RF antenna16and the second RF antenna32, and RF receive signals may be received via the second RF antenna32. In an alternate embodiment of the RF communications circuitry54, the second RF filter structure120is coupled to the RF transmit circuitry64, such that the antenna system in the RF communications circuitry54is a SIMO antenna system.

A multiple-input single-output (MISO) antenna system is a system in which RF transmit signals may be transmitted from the first RF antenna16, and RF receive signals may be simultaneously received via the first RF antenna16and the second RF antenna32. In an additional embodiment of the RF communications circuitry54, the first RF filter structure60is coupled to the RF receive circuitry62, such that the antenna system in the RF communications circuitry54is a MISO antenna system.

A multiple-input multiple-output (MIMO) antenna system is a system in which RF transmit signals may be simultaneously transmitted from the first RF antenna16and the second RF antenna32, and RF receive signals may be simultaneously received via the first RF antenna16and the second RF antenna32. In another embodiment of the RF communications circuitry54, the second RF filter structure120is coupled to the RF transmit circuitry64and the first RF filter structure60is coupled to the RF receive circuitry62, such that the antenna system in the RF communications circuitry54is a MIMO antenna system.

FIG. 14shows the RF communications circuitry54according to another embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 14is similar to the RF communications circuitry54illustrated inFIG. 11, except in the RF communications circuitry54illustrated inFIG. 14, the first RF filter structure60further includes a fifth tunable RF filter path122and a sixth tunable RF filter path124, and the RF front-end circuitry58further includes a fifth connection node126and a sixth connection node128. Additionally, the RF front-end control circuitry98shown inFIG. 11is not shown inFIG. 14to simplifyFIG. 14.

In one embodiment of the fifth tunable RF filter path122, the fifth tunable RF filter path122includes a fifth pair (not shown) of weakly coupled resonators. In one embodiment of the sixth tunable RF filter path124, the sixth tunable RF filter path124includes a sixth pair (not shown) of weakly coupled resonators.

In one embodiment of the fifth tunable RF filter path122and the sixth tunable RF filter path124, the fifth tunable RF filter path122is directly coupled between the first common connection node74and the fifth connection node126, and the sixth tunable RF filter path124is directly coupled between the sixth connection node128and the first common connection node74. In another embodiment of the RF communications circuitry54, the first RF antenna16is omitted. Additionally, the RF receive circuitry62is further coupled between the sixth connection node128and the RF system control circuitry56, and the RF transmit circuitry64is further coupled between the fifth connection node126and the RF system control circuitry56.

In one embodiment of the RF communications circuitry54, the sixth tunable RF filter path124is a third RF receive filter, such that the first RF antenna16forwards a third received RF signal via the first common connection node74to provide a third upstream RF receive signal RU3to the sixth tunable RF filter path124, which receives and filters the third upstream RF receive signal RU3to provide a third filtered RF receive signal RF3to the RF receive circuitry62, which processes the third filtered RF receive signal RF3to provide the third receive signal RX3to the RF system control circuitry56.

In one embodiment of the RF communications circuitry54, the fifth tunable RF filter path122is a third RF transmit filter, such that the RF system control circuitry56provides a third transmit signal TX3to the RF transmit circuitry64, which processes the third transmit signal TX3to provide a third upstream RF transmit signal TU3to the fifth tunable RF filter path122. The fifth tunable RF filter path122receives and filters the third upstream RF transmit signal TU3to provide a third filtered RF transmit signal TF3, which is transmitted via the first common connection node74by the first RF antenna16.

In one embodiment of the RF communications circuitry54, the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122, and the sixth tunable RF filter path124do not significantly load one another at frequencies of interest. Therefore, antenna switching circuitry34,42(FIG. 3) may be avoided. As such, by directly coupling the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122and the sixth tunable RF filter path124to the first common connection node74; front-end RF switching elements may be avoided, thereby reducing cost, size, and non-linearity; and increasing efficiency and flexibility of the RF communications circuitry54.

In one embodiment of the RF communications circuitry54, the RF communications circuitry54is an FDD communications system, such that each of the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122, and the sixth tunable RF filter path124is a bandpass filter having a unique center frequency. As such, in one embodiment of the RF system control circuitry56, the first filter parameter of each of the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122, and the sixth tunable RF filter path124is a unique center frequency.

FIG. 15shows the RF communications circuitry54according to a further embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 15is similar to the RF communications circuitry54illustrated inFIG. 4, except in the RF communications circuitry54illustrated inFIG. 15, the RF front-end circuitry58further includes an RF antenna switch130and the third connection node114. Additionally, the first RF filter structure60further includes the third tunable RF filter path110. Instead of the first RF antenna16being directly coupled to the first common connection node74, as illustrated inFIG. 4, the RF antenna switch130is coupled between the first RF antenna16and the first common connection node74. As such, the first common connection node74is coupled to the first RF antenna16via the RF antenna switch130. In this regard, the RF communications circuitry54is a hybrid RF communications system.

The RF antenna switch130has an antenna switch common connection node132, an antenna switch first connection node134, an antenna switch second connection node136, and an antenna switch third connection node138. The antenna switch common connection node132is coupled to the first RF antenna16. In one embodiment of the RF antenna switch130, the antenna switch common connection node132is directly coupled to the first RF antenna16. The antenna switch first connection node134is coupled to the first common connection node74. In one embodiment of the RF antenna switch130, the antenna switch first connection node134is directly coupled to the first common connection node74. The antenna switch second connection node136may be coupled to other circuitry (not shown). The antenna switch third connection node138may be coupled to other circuitry (not shown). In another embodiment of the RF antenna switch130, the antenna switch third connection node138is omitted. In a further embodiment of the RF antenna switch130, the RF antenna switch130has at least one additional connection node.

The RF system control circuitry56provides a switch control signal SCS to the RF antenna switch130. As such, the RF system control circuitry56selects one of the antenna switch first connection node134, the antenna switch second connection node136, and the antenna switch third connection node138to be coupled to the antenna switch common connection node132using the switch control signal SCS.

The third tunable RF filter path110is directly coupled between the first common connection node74and the third connection node114. In one embodiment of the RF communications circuitry54, the third tunable RF filter path110is a second RF receive filter, such that the first RF antenna16forwards a received RF signal via the RF antenna switch130and the first common connection node74to provide the second upstream RF receive signal RU2to the third tunable RF filter path110, which receives and filters the second upstream RF receive signal RU2to provide the second filtered RF receive signal RF2to the RF receive circuitry62. The RF receive circuitry62processes the second filtered RF receive signal RF2to provide a second receive signal RX2to the RF system control circuitry56.

The RF system control circuitry56further provides the third filter control signal FCS3. As such, in one embodiment of the RF communications circuitry54, the RF system control circuitry56tunes a first filter parameter of the third tunable RF filter path110using the third filter control signal FCS3. In one embodiment of the RF communications circuitry54, the RF communications circuitry54uses the second tunable RF filter path68and the third tunable RF filter path110to provide receive CA. In an alternate embodiment of the RF communications circuitry54, tunable RF filters allow for sharing a signal path to provide both an FDD signal path and a TDD signal path, thereby lowering front-end complexity.

FIG. 16shows the RF communications circuitry54according to one embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 16is similar to the RF communications circuitry54illustrated inFIG. 15, except in the RF communications circuitry54illustrated inFIG. 16, the third tunable RF filter path110is omitted. Additionally, in one embodiment of the RF communications circuitry54, the RF receive circuitry62, the RF transmit circuitry64, and the first RF filter structure60are all broadband devices. As such, the RF communications circuitry54is broadband circuitry capable of processing RF signals having wide frequency ranges.

FIG. 17shows the RF communications circuitry54according to an alternate embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 17is similar to the RF communications circuitry54illustrated inFIG. 16, except in the RF communications circuitry54illustrated inFIG. 17, the RF receive circuitry62is omitted and the RF front-end circuitry58further includes a first RF front-end circuit140, a second RF front-end circuit142, and a third RF front-end circuit144.

The first RF front-end circuit140includes the RF transmit circuitry64. The second RF front-end circuit142includes the first RF filter structure60, the first connection node70, the second connection node72, and the first common connection node74. The third RF front-end circuit144includes the RF antenna switch130. In one embodiment of the first RF front-end circuit140, the first RF front-end circuit140is a first RF front-end integrated circuit (IC). In one embodiment of the second RF front-end circuit142, the second RF front-end circuit142is a second RF front-end IC. In one embodiment of the third RF front-end circuit144, the third RF front-end circuit144is a third RF front-end IC.

FIG. 18shows the RF communications circuitry54according to an additional embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 18is similar to the RF communications circuitry54illustrated inFIG. 16, except in the RF communications circuitry54illustrated inFIG. 18, the RF receive circuitry62is omitted and the RF front-end circuitry58further includes the first RF front-end circuit140and the second RF front-end circuit142.

The first RF front-end circuit140includes the RF transmit circuitry64. The second RF front-end circuit142includes the first RF filter structure60, the RF antenna switch130, the first connection node70, the second connection node72, and the first common connection node74. In one embodiment of the first RF front-end circuit140, the first RF front-end circuit140is the first RF front-end IC. In one embodiment of the second RF front-end circuit142, the second RF front-end circuit142is the second RF front-end IC.

FIG. 19shows the RF communications circuitry54according to another embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 19is similar to the RF communications circuitry54illustrated inFIG. 16, except in the RF communications circuitry54illustrated inFIG. 19, the RF receive circuitry62is omitted and the RF front-end circuitry58further includes the first RF front-end circuit140.

The first RF front-end circuit140includes the RF transmit circuitry64, the first RF filter structure60, the RF antenna switch130, the first connection node70, the second connection node72, and the first common connection node74. In one embodiment of the first RF front-end circuit140, the first RF front-end circuit140is the first RF front-end IC.

FIG. 20shows the RF communications circuitry54according to a further embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 20is a TDD system, which is capable of transmitting and receiving RF signals, but not simultaneously. As such, the RF communications circuitry54illustrated inFIG. 20is similar to the RF communications circuitry54illustrated inFIG. 4, except in the RF communications circuitry54illustrated inFIG. 20, the second tunable RF filter path68and the second connection node72are omitted, and the RF front-end circuitry58further includes an RF transmit/receive switch146coupled between the first tunable RF filter path66and the RF receive circuitry62, and further coupled between the first tunable RF filter path66and the RF transmit circuitry64.

Since the RF communications circuitry54does not simultaneously transmit and receive RF signals, the first tunable RF filter path66provides front-end transmit filtering when the RF communications circuitry54is transmitting RF signals and the first tunable RF filter path66provides front-end receive filtering when the RF communications circuitry54is receiving RF signals. In this regard, the first tunable RF filter path66processes half-duplex signals.

The RF transmit/receive switch146has a transmit/receive switch common connection node148, a transmit/receive switch first connection node150, and a transmit/receive switch second connection node152. The RF receive circuitry62is coupled between the RF system control circuitry56and the transmit/receive switch second connection node152. The RF transmit circuitry64is coupled between the RF system control circuitry56and the transmit/receive switch first connection node150. The first connection node70is coupled to the transmit/receive switch common connection node148.

The RF system control circuitry56provides a switch control signal SCS to the RF transmit/receive switch146. As such, the RF system control circuitry56selects either the transmit/receive switch first connection node150or the transmit/receive switch second connection node152to be coupled to the transmit/receive switch common connection node148using the switch control signal SCS. Therefore, when the RF communications circuitry54is transmitting RF signals, the RF transmit circuitry64is coupled to the first tunable RF filter path66and the RF receive circuitry62is not coupled to the first tunable RF filter path66. Conversely, when the RF communications circuitry54is receiving RF signals, the RF receive circuitry62is coupled to the first tunable RF filter path66and the RF transmit circuitry64is not coupled to the first tunable RF filter path66.

FIG. 21illustrates an exemplary embodiment of the first RF filter structure60. The first RF filter structure60includes a plurality of resonators (referred to generically as elements R and specifically as elements R(i,j), where an integer i indicates a row position and an integer j indicates a column position, where 1≦i≦M, 1≦j≦N and M is any integer greater than 1 and N is any integer greater than to 1. It should be noted that in alternative embodiments the number of resonators R in each row and column may be the same or different). The first tunable RF filter path66includes row1of weakly coupled resonators R(1,1), R(1,2) through (R(1,N). All of the weakly coupled resonators R(1,1), R(1,2) through (R(1,N) are weakly coupled to one another. Furthermore, the first tunable RF filter path66is electrically connected between terminal200and terminal202. In this manner, the first tunable RF filter path66is configured to receive RF signals and output filtered RF signals. The second tunable RF filter path68includes row M of weakly coupled resonators R(M,1), R(M,2) through R(M,N). All of the weakly coupled resonators R(M,1), R(M,2) through R(M,N) are weakly coupled to one another. Furthermore, the second tunable RF filter path68is electrically connected between terminal204and terminal206. In this manner, the second tunable RF filter path68is configured to receive RF signals and output filtered RF signals. It should be noted that the first RF filter structure60may include any number of tunable RF filter paths, such as, for example, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122, and the sixth tunable RF filter path124, described above with respect toFIGS. 11-14. Each of the resonators R may be a tunable resonator, which allows for a resonant frequency of each of the resonators R to be varied to along a frequency range. In some embodiments, not all of the couplings between the resonators R are weak. A hybrid architecture having at least one pair of weakly coupled resonators R and strongly or moderately coupled resonators R is also possible.

Cross-coupling capacitive structures C are electrically connected to and between the resonators R. In this embodiment, each of the cross-coupling capacitive structures C is a variable cross-coupling capacitive structure, such as a varactor or an array of capacitors. To be independent, the magnetic couplings may be negligible. Alternatively, the cross-coupling capacitive structures C may simply be provided by a capacitor with a fixed capacitance. With regard to the exemplary embodiment shown inFIG. 21, the tunable RF filter paths of the first RF filter structure60are independent of one another. As such, the first tunable RF filter path66and the second tunable RF filter path68are independent of one another and thus do not have cross-coupling capacitive structures C between their resonators. Thus, in this embodiment, the cross-coupling capacitive structures C do not connect any of the weakly coupled resonators R(1,1), R(1,2) through (R(1,N) to any of the weakly coupled resonators R(M,1), R(M,2) through (R(M,N). This provides increased isolation between the first tunable RF filter path66and the second tunable RF filter path68. In general, energy transfer between two weakly coupled resonators R in the first tunable RF filter path66and the second tunable RF filter path68may be provided by multiple energy transfer components. For example, energy may be transferred between the resonators R only through mutual magnetic coupling, only through mutual electric coupling, or through both mutual electric coupling and mutual magnetic coupling. Ideally, all of the mutual coupling coefficients are provided as designed, but in practice, the mutual coupling coefficients also be the result of parasitics. The inductors of the resonators R may also have magnetic coupling between them. A total coupling between the resonators R is given by the sum of magnetic and electric coupling.

In order to provide the transfer functions of the tunable RF filter paths66,68with high out-of-band attenuation and a relatively low filter order, the tunable RF filter paths66,68are configured to adjust notches in the transfer function, which are provided by the resonators R within the tunable RF filter paths66,68. The notches can be provided using parallel tanks connected in series or in shunt along a signal path of the first tunable RF filter path66. To provide the notches, the parallel tanks operate approximately as an open circuit or as short circuits at certain frequencies. The notches can also be provided using multi-signal path cancellation. In this case, the tunable RF filter paths66,68may be smaller and/or have fewer inductors. To tune the total mutual coupling coefficients between the resonators R towards a desired value, the tunable RF filter paths66,68are configured to vary variable electric coupling coefficients so that parasitic couplings between the resonators R in the tunable RF filter paths66,68are absorbed into a desired frequency transfer function.

FIG. 22illustrates an exemplary embodiment of the first tunable RF filter path66in the first RF filter structure60shown inFIG. 21. While the exemplary embodiment shown inFIG. 22is of the first tunable RF filter path66, any of the tunable RF filter paths shown in the first RF filter structure60ofFIG. 21may be arranged in accordance with the exemplary embodiment shown inFIG. 22. The first tunable RF filter path66shown inFIG. 22includes an embodiment of the resonator R(1,1) and an embodiment of the resonator R(1,2). The resonator R(1,1) and the resonator R(1,2) are weakly coupled to one another. More specifically, the resonator R(1,1) includes an inductor208and a capacitive structure210. The resonator R(1,2) includes an inductor212, a capacitive structure214, and a capacitive structure216.

The resonator R(1,1) and the resonator R(1,2) are a pair of weakly coupled resonators. The resonator R(1,1) and the resonator R(1,2) are weakly coupled by providing the inductor208and the inductor212such that the inductor208and the inductor212are weakly magnetically coupled. Although the resonator R(1,1) and the resonator R(1,2) are weakly coupled, the inductor212has a maximum lateral width and a displacement between the inductor208and the inductor212is less than or equal to half the maximum lateral width of the inductor212. As such, the inductor208and the inductor212are relatively close to one another. The displacement between the inductor208and the inductor212may be measured from a geometric centroid of the inductor208to a geometric centroid of the inductor212. The maximum lateral width may be a maximum dimension of the inductor212along a plane defined by its largest winding. The weak coupling between the inductor208and the inductor212is obtained through topological techniques. For example, the inductor208and the inductor212may be fully or partially aligned, where winding(s) of the inductor208and winding(s) of the inductor212are configured to provide weak coupling through cancellation. Alternatively or additionally, a plane defining an orientation of the winding(s) of the inductor208and a plane defining an orientation of the winding(s) of the inductor212may be fully or partially orthogonal to one another. Some of the magnetic couplings between the resonators R can be unidirectional (passive or active). This can significantly improve isolation (e.g., transmit and receive isolation in duplexers).

To maximize the quality (Q) factor of the tunable RF filter paths66through68, most of the total mutual coupling should be realized magnetically, and only fine-tuning is provided electrically. This also helps to reduce common-mode signal transfer in the differential resonators and thus keeps the Q factor high. While the magnetic coupling can be adjusted only statically, with a new layout design, the electric coupling can be tuned on the fly (after fabrication). The filter characteristics (e.g., bias network structure, resonator capacitance) can be adjusted based on given coupling coefficients to maximize filter performance.

To provide a tuning range to tune a transfer function of the first tunable RF filter path66and provide a fast roll-off from a low-frequency side to a high-frequency side of the transfer function, the first tunable RF filter path66is configured to change a sign of a total mutual coupling coefficient between the resonator R(1,1) and the resonator R(1,2). Accordingly, the first tunable RF filter path66includes a cross-coupling capacitive structure C(P1) and a cross-coupling capacitive structure C(N1). The cross-coupling capacitive structure C(P1) and the cross-coupling capacitive structure C(N1) are embodiments of the cross-coupling capacitive structures C described above with regard toFIG. 21. As shown inFIG. 22, the cross-coupling capacitive structure C(P1) is electrically connected between the resonator R(1,1) and the resonator R(1,2) so as to provide a positive coupling coefficient between the resonator R(1,1) and the resonator R(1,2). The cross-coupling capacitive structure C(P1) is a variable cross-coupling capacitive structure configured to vary the positive coupling coefficient provided between the resonator R(1,1) and the resonator R(1,2). The cross-coupling capacitive structure C(N1) is electrically connected between the resonator R(1,1) and the resonator R(1,2) so as to provide a negative coupling coefficient between the resonator R(1,1) and the resonator R(1,2). The cross-coupling capacitive structure C(N1) is a variable cross-coupling capacitive structure configured to vary the negative coupling coefficient provided between the resonator R(1,1) and the resonator R(1,2). The arrangement of the cross-coupling capacitive structure C(P1) and the cross-coupling capacitive structure C(N1) shown inFIG. 22is a V-bridge structure. In alternative embodiments, some or all of the cross-coupling capacitive structures is fixed (not variable).

In the resonator R(1,1), the inductor208and the capacitive structure210are electrically connected in parallel. More specifically, the inductor208has an end217and an end218, which are disposed opposite to one another. The ends217,218are each electrically connected to the capacitive structure210, which is grounded. Thus, the resonator R(1,1) is a single-ended resonator. On the other hand, the inductor212is electrically connected between the capacitive structure214and the capacitive structure216. More specifically, the inductor212has an end220and an end222, which are disposed opposite to one another. The end220is electrically connected to the capacitive structure214and the end222is electrically connected to the capacitive structure216. Both the capacitive structure214and the capacitive structure216are grounded. Thus, the resonator R(1,2) is a differential resonator. In an alternative, an inductor with a center tap can be used. The tap can be connected to ground and only a single capacitive structure can be used. In yet another embodiment, both an inductor and a capacitive structure may have a center tap that is grounded. In still another embodiment, neither the inductor nor the capacitive structure may have a grounded center tap.

The inductor208is magnetically coupled to the inductor212such that an RF signal received at the end217of the inductor208with a voltage polarity (i.e., either a positive voltage polarity or a negative voltage polarity) results in a filtered RF signal being transmitted out the end220of the inductor212with the same voltage polarity. Also, the inductor212is magnetically coupled to the inductor208such that an RF signal received at the end220of the inductor212with a voltage polarity (i.e., either a positive voltage polarity or a negative voltage polarity) results in a filtered RF signal being transmitted out the end217of the inductor208with the same voltage polarity. This is indicated inFIG. 22by the dot convention where a dot is placed at the end217of the inductor208and a dot is placed at the end220of the inductor212. By using two independent and adjustable coupling coefficients (i.e., the positive coupling coefficient and the negative coupling coefficient) with the resonator R(1,2) (i.e., the differential resonator), the transfer function of the first tunable RF filter path66is provided so as to be fully adjustable. More specifically, the inductors208,212may be magnetically coupled so as to have a low magnetic coupling coefficient through field cancellation, with the variable positive coupling coefficient and the variable negative coupling coefficient. In this case, the inductor208and the inductor212are arranged such that a mutual magnetic coupling between the inductor208and the inductor212cancel. Alternatively, the inductor208and the inductor212are arranged such that the inductor212reduces a mutual magnetic coupling coefficient of the inductor208. With respect to the magnetic coupling coefficient, the variable positive coupling coefficient is a variable positive electric coupling coefficient and the variable negative coupling coefficient is a variable negative electric coupling coefficient. The variable positive electric coupling coefficient and the variable negative electric coupling coefficient oppose each other to create a tunable filter characteristic.

The resonator R(1,2) is operably associated with the resonator R(1,1) such that an energy transfer factor between the resonator R(1,1) and the resonator R(1,2) is less than 10%. A total mutual coupling between the resonator R(1,1) and the resonator R(1,2) is provided by a sum total of the mutual magnetic factor between the resonator R(1,1) and the resonator R(1,2) and the mutual electric coupling coefficients between the resonator R(1,1) and the resonator R(1,2). In this embodiment, the mutual magnetic coupling coefficient between the inductor208and the inductor212is a fixed mutual magnetic coupling coefficient. Although embodiments of the resonators R(1,1), R(1,2) may be provided so as to provide a variable magnetic coupling coefficient between the resonators R(1,1), R(1,2), embodiments of the resonators R(1,1), R(1,2) that provide variable magnetic couplings can be costly and difficult to realize. However, providing variable electric coupling coefficients (i.e., the variable positive electric coupling coefficient and the variable electric negative coupling coefficient) is easier and more economical. Thus, using the cross-coupling capacitive structure C(P1) and the cross-coupling capacitive structure C(N1) to provide the variable positive electric coupling coefficient and the variable electric negative coupling coefficient is an economical technique for providing a tunable filter characteristic between the resonators R(1,1), R(1,2). Furthermore, since the mutual magnetic coupling coefficient between the inductor208and the inductor212is fixed, the first tunable RF filter path66has lower insertion losses.

In the embodiment shown inFIG. 22, the inductor208and the212inductor are the same size. Alternatively, the inductor208and the inductor212may be different sizes. For example, the inductor212may be smaller than the inductor208. By determining a distance between the inductor208and the inductor212, the magnetic coupling coefficient between the inductor208and the inductor212can be set. With regard to the inductors208,212shown inFIG. 22, the inductor208may be a folded inductor configured to generate a first confined magnetic field, while the inductor212may be a folded inductor configured to generate a second confined magnetic field. Magnetic field lines of the first confined magnetic field and of the second confined magnetic field that are external to the inductor208and inductor212are cancelled by opposing magnetic field lines in all directions. When the inductor208and the inductor212are folded inductors, the folded inductors can be stacked. This allows building the first tunable RF filter path66such that several inductors208,212are stacked. Furthermore, this arrangement allows for a specially sized interconnect structure that electrically connects the inductors208,212to the capacitive structure210, the capacitive structure214, the capacitive structure216, the cross-coupling capacitive structure C(P1), and the cross-coupling capacitive structure C(N1). The specially sized interconnect increases the Q factor of the capacitive structure210, the capacitive structure214, the capacitive structure216, the cross-coupling capacitive structure C(P1), and the cross-coupling capacitive structure C(N1), and allows for precise control of their variable capacitances. Weakly coupled filters can also be realized with planar field cancellation structures.

FIG. 23illustrates an exemplary embodiment of the first tunable RF filter path66in the first RF filter structure60shown inFIG. 21. While the exemplary embodiment shown inFIG. 23is of the first tunable RF filter path66, any of the tunable RF filter paths shown in the first RF filter structure60ofFIG. 21may be arranged in accordance with the exemplary embodiment shown inFIG. 23. The first tunable RF filter path66shown inFIG. 23includes an embodiment of the resonator R(1,1) and an embodiment of the resonator R(1,2). The resonator R(1,1) and the resonator R(1,2) are weakly coupled to one another. The embodiment of the resonator R(1,2) is the same as the embodiment of the resonator R(1,2) shown inFIG. 22. Thus, the resonator R(1,2) shown inFIG. 23is a differential resonator that includes the inductor212, the capacitive structure214, and the capacitive structure216. Additionally, like the embodiment of the resonator R(1,1) shown inFIG. 22, the embodiment of the resonator R(1,1) shown inFIG. 23includes the inductor208and the capacitive structure210. However, in this embodiment, the resonator R(1,1) shown inFIG. 23is a differential resonator and further includes a capacitive structure224. More specifically, the end217of the inductor208is electrically connected to the capacitive structure210and the end218of the inductor208is electrically connected to the capacitive structure224. Both the capacitive structure210and the capacitive structure224are grounded. Like the capacitive structure210, the capacitive structure224is also a variable capacitive structure, such as a programmable array of capacitors or a varactor. Alternatively, a center tap of an inductor may be grounded. In yet another embodiment, the inductor and a capacitive structure may be RF floating (a low-resistance connection to ground).

The resonator R(1,1) and the resonator R(1,2) are a pair of weakly coupled resonators. Like the first tunable RF filter path66shown inFIG. 22, the resonator R(1,1) and the resonator R(1,2) are weakly coupled by providing the inductor208and the inductor212such that the inductor208and the inductor212are weakly coupled. Thus, the inductor208and the inductor212may have a magnetic coupling coefficient that is less than or equal to approximately 0.3. Although the resonator R(1,1) and the resonator R(1,2) are weakly coupled, a displacement between the inductor208and the inductor212is less than or equal to half the maximum lateral width of the inductor212. As such, the inductor208and the inductor212are relatively close to one another. The displacement between the inductor208and the inductor212may be measured from a geometric centroid of the inductor208to a geometric centroid of the inductor212. The maximum lateral width may be a maximum dimension of the inductor212along a plane defined by its largest winding.

The weak coupling between the inductor208and the inductor212is obtained through topological techniques. For example, the inductor208and the inductor212may be fully or partially aligned, where winding(s) of the inductor208and winding(s) of the inductor212are configured to provide weak coupling through cancellation. Alternatively or additionally, a plane defining an orientation of the windings of the inductor208and a plane defining an orientation of the windings of the inductor212may be fully or partially orthogonal to one another.

The resonator R(1,2) is operably associated with the resonator R(1,1) such that an energy transfer factor between the resonator R(1,1) and the resonator R(1,2) is less than 10%. To provide a tuning range to tune a transfer function of the first tunable RF filter path66such to provide a fast roll-off from a low-frequency side to a high-frequency side requires changing a sign of the total mutual coupling coefficient between the resonator R(1,1) and the resonator R(1,2). Like the embodiment of the first tunable RF filter path66shown inFIG. 22, the first tunable RF filter path66shown inFIG. 23includes the cross-coupling capacitive structure C(P1) and the cross-coupling capacitive structure C(N1). The cross-coupling capacitive structure C(P1) and the cross-coupling capacitive structure C(N1) are arranged in the same manner described above with respect toFIG. 22. However, in this embodiment, the first tunable RF filter path66shown inFIG. 23also includes a cross-coupling capacitive structure C(P2) and a cross-coupling capacitive structure C(N2). The cross-coupling capacitive structure C(P2) and the cross-coupling capacitive structure C(N2) are also embodiments of the cross-coupling capacitive structures C described above with regard toFIG. 21.

As described above with respect toFIG. 22, the cross-coupling capacitive structure C(P1) is electrically connected between the resonator R(1,1) and the resonator R(1,2) so as to provide the positive coupling coefficient (i.e., the variable positive electric coupling coefficient) between the resonator R(1,1) and the resonator R(1,2). Also as described above with respect toFIG. 22, the cross-coupling capacitive structure C(N1) is electrically connected between the resonator R(1,1) and the resonator R(1,2) so as to provide the negative coupling coefficient (i.e., the variable negative electric coupling coefficient) between the resonator R(1,1) and the resonator R(1,2). With regard to the cross-coupling capacitive structure C(P2), the cross-coupling capacitive structure C(P2) is electrically connected between the resonator R(1,1) and the resonator R(1,2) so as to provide another positive coupling coefficient (i.e., another variable positive electric coupling coefficient) between the resonator R(1,1) and the resonator R(1,2). In this embodiment, the cross-coupling capacitive structure C(P2) is electrically connected between the end218of the inductor208and the end222of the inductor212. The cross-coupling capacitive structure C(P2) is a variable cross-coupling capacitive structure configured to vary the other positive coupling coefficient (i.e., the other variable positive electric coupling coefficient) provided between the resonator R(1,1) and the resonator R(1,2). With regard to the cross-coupling capacitive structure C(N2), the cross-coupling capacitive structure C(N2) is electrically connected between the resonator R(1,1) and the resonator R(1,2) so as to provide another negative coupling coefficient (i.e., another variable negative electric coupling coefficient) between the resonator R(1,1) and the resonator R(1,2). In this embodiment, the cross-coupling capacitive structure C(N2) is electrically connected between the end218of the inductor208and the end220of the inductor212. The cross-coupling capacitive structure C(N2) is a variable cross-coupling capacitive structure configured to vary the negative coupling coefficient (i.e., the other variable negative electric coupling coefficient) provided between the resonator R(1,1) and the resonator R(1,2). The arrangement of the cross-coupling capacitive structure C(P1), the cross-coupling capacitive structure C(N1), the cross-coupling capacitive structure C(P2), and the cross-coupling capacitive structure C(N2) shown inFIG. 23is an X-bridge structure.

As shown inFIG. 23, the resonator R(1,2) is operably associated with the resonator R(1,1) such that an energy transfer factor between the resonator R(1,1) and the resonator R(1,2) is less than 10%. The total mutual coupling between the resonator R(1,1) and the resonator R(1,2) is provided by a sum total of the mutual magnetic factor between the resonator R(1,1) and the resonator R(1,2) and the mutual electric coupling coefficients between the resonator R(1,1) and the resonator R(1,2). Thus, in this embodiment, the total mutual coupling between the resonator R(1,1) and the resonator R(1,2) is provided by the sum total of the mutual magnetic coupling coefficient, the variable positive electric coupling coefficient provided by the cross-coupling capacitive structure C(P1), the variable negative electric coupling coefficient provided by the cross-coupling capacitive structure C(N1), the other variable positive electric coupling coefficient provided by the cross-coupling capacitive structure C(P2), and the other variable negative electric coupling coefficient provided by the cross-coupling capacitive structure C(N2).

FIG. 24illustrates an exemplary embodiment of the first tunable RF filter path66in the first RF filter structure60shown inFIG. 21. While the exemplary embodiment shown inFIG. 24is of the first tunable RF filter path66, any of the tunable RF filter paths shown in the first RF filter structure60ofFIG. 21may be arranged in accordance with the exemplary embodiment shown inFIG. 24. The first tunable RF filter path66shown inFIG. 24includes an embodiment of the resonator R(1,1) and an embodiment of the resonator R(1,2). The resonator R(1,1) and the resonator R(1,2) are weakly coupled to one another. The embodiment of the resonator R(1,1) is the same as the embodiment of the resonator R(1,1) shown inFIG. 22. Thus, the resonator R(1,1) shown inFIG. 24is a single-ended resonator that includes the inductor208and the capacitive structure210. Additionally, like the embodiment of the resonator R(1,2) shown inFIG. 22, the embodiment of the resonator R(1,2) shown inFIG. 24includes the inductor212and the capacitive structure214. However, in this embodiment, the resonator R(1,2) shown inFIG. 24is a single-ended resonator. More specifically, the end220and the end222of the inductor212are each electrically connected to the capacitive structure214, which is grounded.

The resonator R(1,1) and the resonator R(1,2) are a pair of weakly coupled resonators. Like the first tunable RF filter path66shown inFIG. 22, the resonator R(1,1) and the resonator R(1,2) are weakly coupled by providing the inductor208and the inductor212such that the inductor208and the inductor212are weakly coupled. Thus, the inductor208and the inductor212may have a magnetic coupling coefficient that is less than or equal to approximately 0.3. Although the resonator R(1,1) and the resonator R(1,2) are weakly coupled, the displacement between the inductor208and the inductor212is less than or equal to half the maximum lateral width of the inductor212. As such, the inductor208and the inductor212are relatively close to one another. The displacement between the inductor208and the inductor212may be measured from the geometric centroid of the inductor208to the geometric centroid of the inductor212. The maximum lateral width may be a maximum dimension of the inductor212along a plane defined by its largest winding. The weak coupling between the inductor208and the inductor212is obtained through topological techniques. For example, the inductor208and the inductor212may be fully or partially aligned, where winding(s) of the inductor208and winding(s) of the inductor212are configured to provide weak coupling through cancellation. Alternatively or additionally, a plane defining an orientation of the windings of the inductor208and a plane defining an orientation of the windings of the inductor212may be fully or partially orthogonal to one another.

The resonator R(1,2) is operably associated with the resonator R(1,1) such that an energy transfer factor between the resonator R(1,1) and the resonator R(1,2) is less than 10%. To provide a tuning range to tune a transfer function of the first tunable RF filter path66and provide a fast roll-off from a low-frequency side to a high-frequency side of the transfer function, the first tunable RF filter path66is configured to change a sign of a total mutual coupling coefficient between the resonator R(1,1) and the resonator R(1,2). However, in this embodiment, the first tunable RF filter path66shown inFIG. 24only includes the cross-coupling capacitive structure C(P1), which is electrically connected between the end217of the inductor208and the end220of the inductor212. As discussed above with respect toFIGS. 22 and 23, the cross-coupling capacitive structure C(P1) is a variable cross-coupling capacitive structure configured to vary the positive coupling coefficient (i.e., the variable positive electric coupling coefficient) provided between the resonator R(1,1) and the resonator R(1,2). Thus, in order to allow for the sign of the total mutual coupling coefficient between the resonator R(1,1) and the resonator R(1,2) to be changed, the inductor208and the inductor212are arranged so as to provide a fixed negative mutual magnetic coupling coefficient between the inductor208of the resonator R(1,1) and the inductor212of the resonator R(1,2). As such, varying the variable positive electric coupling coefficient allows for the sign of the total mutual coupling coefficient between the resonator R(1,1) and the resonator R(1,2) to be changed using only the cross-coupling capacitive structure C(P1).

As such, in this embodiment, the inductor208is magnetically coupled to the inductor212such that an RF signal received at the end217of the inductor208with a voltage polarity (i.e., either a positive voltage polarity or a negative voltage polarity) results in a filtered RF signal with the same voltage polarity being transmitted out the end222of the inductor212. In addition, the inductor212is magnetically coupled to the inductor208such that an RF signal received at the end222of the inductor212with a voltage polarity (i.e., either a positive voltage polarity or a negative voltage polarity) results in a filtered RF signal with the same voltage polarity being transmitted out the end217of the inductor208. This is indicated inFIG. 24by the dot convention where a dot is placed at the end217of the inductor208and a dot is placed at the end222of the inductor212. By using the fixed negative mutual magnetic coupling coefficient and the variable positive electric coupling coefficient, the transfer function of the first tunable RF filter path66is provided so to be fully adjustable. The arrangement of the cross-coupling capacitive structure C(P1) shown inFIG. 24is a single positive bridge structure.

FIG. 25illustrates another exemplary embodiment of the first tunable RF filter path66in the first RF filter structure60shown inFIG. 21. While the exemplary embodiment shown inFIG. 25is of the first tunable RF filter path66, any of the tunable RF filter paths shown in the first RF filter structure60ofFIG. 21may be arranged in accordance with the exemplary embodiment shown inFIG. 25. The first tunable RF filter path66shown inFIG. 25includes an embodiment of the resonator R(1,1) and an embodiment of the resonator R(1,2). The resonator R(1,1) and the resonator R(1,2) are weakly coupled to one another. The embodiment of the resonator R(1,1) is the same as the embodiment of the resonator R(1,1) shown inFIG. 22. Thus, the resonator R(1,1) shown inFIG. 25is a single-ended resonator that includes the inductor208and the capacitive structure210, which are arranged in the same manner described above with respect toFIG. 22. Like the resonator R(1,2) shown inFIG. 24, the resonator R(1,2) shown inFIG. 25is a single-ended resonator that includes the inductor212and the capacitive structure214. However, the inductor208shown inFIG. 25is magnetically coupled to the inductor212such that an RF signal received at the end217of the inductor208with a voltage polarity (i.e., either a positive voltage polarity or a negative voltage polarity) results in a filtered RF signal with the same voltage polarity being transmitted out the end220of the inductor212. Also, the inductor212shown inFIG. 25is magnetically coupled to the inductor208such that an RF signal received at the end220of the inductor212with a voltage polarity (i.e., either a positive voltage polarity or a negative voltage polarity) results in a filtered RF signal with the same voltage polarity being transmitted out the end217of the inductor208. This is indicated inFIG. 25by the dot convention where a dot is placed at the end217of the inductor208and a dot is placed at the end220of the inductor212. In alternative embodiments, the resonator R(1,2) is a differential resonator. In yet another alternative embodiment, the resonator R(1,1) is a single-ended resonator while the resonator R(1,2) is a differential resonator.

The resonator R(1,1) and the resonator R(1,2) are a pair of weakly coupled resonators. Like the first tunable RF filter path66shown inFIG. 22, the resonator R(1,1) and the resonator R(1,2) are weakly coupled by providing the inductor208and the inductor212such that the inductor208and the inductor212are weakly coupled. Thus, the inductor208and the inductor212may have a fixed magnetic coupling coefficient that is less than or equal to approximately 0.3. Although the resonator R(1,1) and the resonator R(1,2) are weakly coupled, a displacement between the inductor208and the inductor212is less than or equal to half the maximum lateral width of the inductor212. As such, the inductor208and the inductor212are relatively close to one another. The displacement between the inductor208and the inductor212may be measured from a geometric centroid of the inductor208to a geometric centroid of the inductor212. The maximum lateral width may be a maximum dimension of the inductor212along a plane defined by its largest winding.

The weak coupling between the inductor208and the inductor212is obtained through topological techniques. For example, the inductor208and the inductor212may be fully or partially aligned, where winding(s) of the inductor208and winding(s) of the inductor212are configured to provide weak coupling through cancellation. Alternatively or additionally, a plane defining an orientation of the windings of the inductor208and a plane defining an orientation of the windings of the inductor212may be fully or partially orthogonal to one another.

The resonator R(1,2) is operably associated with the resonator R(1,1) such that an energy transfer factor between the resonator R(1,1) and the resonator R(1,2) is less than 10%. To provide a tuning range to tune the transfer function of the first tunable RF filter path66and to provide a fast roll-off from the low-frequency side to the high-frequency side of the transfer function, the first tunable RF filter path66is configured to change the sign of the total mutual coupling coefficient between the resonator R(1,1) and the resonator R(1,2). In this embodiment, the first tunable RF filter path66shown inFIG. 25includes a cross-coupling capacitive structure C(PH1), a cross-coupling capacitive structure (CNH1), a cross-coupling capacitive structure C(I1), a cross-coupling capacitive structure C(PH2), and a cross-coupling capacitive structure C(NH2). The cross-coupling capacitive structure C(PH1), the cross-coupling capacitive structure (CNH1), the cross-coupling capacitive structure C(I1), the cross-coupling capacitive structure C(PH2), and the cross-coupling capacitive structure C(NH2) are also embodiments of the cross-coupling capacitive structures C described above with regard toFIG. 21.

The cross-coupling capacitive structure C(PH1) and the cross-coupling capacitive structure C(NH1) are arranged to form a first capacitive voltage divider. The first capacitive voltage divider is electrically connected to the resonator R(1,1). More specifically, the cross-coupling capacitive structure C(PH1) is electrically connected between the end217of the inductor208and a common connection node H1. The cross-coupling capacitive structure C(NH1) is electrically connected between the end218of the inductor208and the common connection node H1. Additionally, the cross-coupling capacitive structure C(PH2) and the cross-coupling capacitive structure C(NH2) are arranged to form a second capacitive voltage divider. The second capacitive voltage divider is electrically connected to the resonator R(1,2). More specifically, the cross-coupling capacitive structure C(PH2) is electrically connected between the end220of the inductor212and a common connection node H2. The cross-coupling capacitive structure C(NH2) is electrically connected between the end222of the inductor212and the common connection node H2. As shown inFIG. 25, the cross-coupling capacitive structure C(I1) is electrically connected between the first capacitive voltage divider and the second capacitive voltage divider. More specifically, the cross-coupling capacitive structure C(I1) is electrically connected between the common connection node H1and the common connection node H2. The arrangement of the cross-coupling capacitive structure C(PH1), the cross-coupling capacitive structure C(NH1), the cross-coupling capacitive structure C(PH2), the cross-coupling capacitive structure C(NH2), and the cross-coupling capacitive structure C(I1) shown inFIG. 25is an H-bridge structure. In an alternative H-bridge structure, the cross-coupling capacitive structure C(I1) is not provided and instead there is a short between the common connection node H1and the common connection node H2. In addition, a center tap of the inductor208may be grounded and/or the common connection node H1may be grounded. Finally, a high impedance to ground may be provided at the common connection node H1.

With regard to the first capacitive voltage divider, the cross-coupling capacitive structure C(PH1) is a variable cross-coupling capacitive structure configured to vary a first variable positive electric coupling coefficient provided between the resonator R(1,1) and the common connection node H1. The cross-coupling capacitive structure C(NH1) is a variable cross-coupling capacitive structure configured to vary a first variable negative electric coupling coefficient provided between the resonator R(1,1) and the common connection node H1. Thus, a mutual electric coupling coefficient of the resonator R(1,1) is approximately equal to the first variable positive electric coupling coefficient and the first variable negative electric coupling coefficient.

With regard to the second capacitive voltage divider, the cross-coupling capacitive structure C(PH2) is a variable cross-coupling capacitive structure configured to vary a second variable positive electric coupling coefficient provided between the resonator R(1,2) and the common connection node H2. The cross-coupling capacitive structure C(NH2) is a variable cross-coupling capacitive structure configured to vary a second variable negative electric coupling coefficient provided between the resonator R(1,2) and the common connection node H2. Thus, a mutual electric coupling coefficient of the resonator R(1,2) is approximately equal to the second variable positive electric coupling coefficient and the second variable negative electric coupling coefficient. Furthermore, the cross-coupling capacitive structure C(I1) is a variable cross-coupling capacitive structure configured to vary a first variable intermediate electric coupling coefficient provided between the common connection node H1and the common connection node H2. The first tunable RF filter path66shown inFIG. 25thus has a total mutual coupling coefficient between the resonator R(1,1) and the resonator R(1,2) equal to the sum total of the mutual magnetic coupling coefficient between the inductor208and the inductor212, the mutual electric coupling coefficient of the resonator R(1,1), the mutual electric coupling coefficient of the resonator R(1,2), and the first variable intermediate electric coupling coefficient provided between the common connection node H1and the common connection node H2. In alternative embodiments, cross-coupling capacitive structures with fixed capacitances are provided.

In one embodiment, the cross-coupling capacitive structure C(PH1), the cross-coupling capacitive structure C(NH1), the cross-coupling capacitive structure C(PH2), the cross-coupling capacitive structure C(NH2), and the cross-coupling capacitive structure C(I1) may each be provided as a varactor. However, the cross-coupling capacitive structure C(PH1), the cross-coupling capacitive structure C(NH1), the cross-coupling capacitive structure C(PH2), the cross-coupling capacitive structure C(NH2), and the cross-coupling capacitive structure C(I1) may each be provided as a programmable array of capacitors in order to reduce insertion losses and improve linearity. The cross-coupling capacitive structure C(PH1), the cross-coupling capacitive structure C(NH1), the cross-coupling capacitive structure C(PH2), the cross-coupling capacitive structure C(NH2), and the cross-coupling capacitive structure C(I1) can also be any combination of suitable variable cross-coupling capacitive structures, such as combinations of varactors and programmable arrays of capacitors. Although the H-bridge structure can provide good linearity and low insertion losses, the H-bridge structure can also suffer from common-mode signal transfer.

FIG. 26illustrates yet another exemplary embodiment of the first tunable RF filter path66in the first RF filter structure60shown inFIG. 21. While the exemplary embodiment shown inFIG. 26is of the first tunable RF filter path66, any of the tunable RF filter paths shown in the first RF filter structure60ofFIG. 21may be arranged in accordance with the exemplary embodiment shown inFIG. 26. The first tunable RF filter path66shown inFIG. 26can be used to ameliorate the common-mode signal transfer of the H-bridge structure shown inFIG. 25. More specifically, the first tunable RF filter path66shown inFIG. 26includes the same embodiment of the resonator R(1,1) and the same embodiment of the resonator R(1,2) described above with respect toFIG. 25. Furthermore, the first tunable RF filter path66shown inFIG. 26includes the first capacitive voltage divider with the cross-coupling capacitive structure C(PH1) and the cross-coupling capacitive structure C(NH1) described above with respect toFIG. 25, the second capacitive voltage divider with the cross-coupling capacitive structure C(PH2) and the cross-coupling capacitive structure (CNH2) described above with respect toFIG. 25, and the cross-coupling capacitive structure C(I1) described above with respect toFIG. 25. However, in this embodiment, the first tunable RF filter path66shown inFIG. 26also includes a cross-coupling capacitive structure C(PH3), a cross-coupling capacitive structure (CNH3), a cross-coupling capacitive structure C(12), a cross-coupling capacitive structure C(PH4), and a cross-coupling capacitive structure C(NH4). The cross-coupling capacitive structure C(PH3), the cross-coupling capacitive structure (CNH3), the cross-coupling capacitive structure C(12), the cross-coupling capacitive structure C(PH4), and the cross-coupling capacitive structure C(NH4) are also embodiments of the cross-coupling capacitive structures C described above with regard toFIG. 21.

As shown inFIG. 26, the cross-coupling capacitive structure C(PH3) and the cross-coupling capacitive structure C(NH3) are arranged to form a third capacitive voltage divider. The third capacitive voltage divider is electrically connected to the resonator R(1,1). More specifically, the cross-coupling capacitive structure C(PH3) is electrically connected between the end217of the inductor208and a common connection node H3. The cross-coupling capacitive structure C(NH3) is electrically connected between the end218of the inductor208and the common connection node H3. Additionally, the cross-coupling capacitive structure C(PH4) and the cross-coupling capacitive structure C(NH4) are arranged to form a fourth capacitive voltage divider. The fourth capacitive voltage divider is electrically connected to the resonator R(1,2). More specifically, the cross-coupling capacitive structure C(PH4) is electrically connected between the end220of the inductor212and a common connection node H4. The cross-coupling capacitive structure C(NH4) is electrically connected between the end222of the inductor212and the common connection node H4. As shown inFIG. 26, the cross-coupling capacitive structure C(12) is electrically connected between first capacitive voltage divider and the second capacitive voltage divider. More specifically, the cross-coupling capacitive structure C(12) is electrically connected between the common connection node H3and the common connection node H4. Alternatively, the cross-coupling capacitive structure C(I1) and the cross-coupling capacitive structure C(12) can be replaced with shorts. The arrangement of the cross-coupling capacitive structure C(PH1), the cross-coupling capacitive structure C(NH1), the cross-coupling capacitive structure C(PH2), the cross-coupling capacitive structure C(NH2), the cross-coupling capacitive structure C(I1), the cross-coupling capacitive structure C(PH3), the cross-coupling capacitive structure C(NH3), the cross-coupling capacitive structure C(PH4), the cross-coupling capacitive structure C(NH4), and the cross-coupling capacitive structure C(12) shown inFIG. 26is a double H-bridge structure.

With regard to the third capacitive voltage divider, the cross-coupling capacitive structure C(PH3) is a variable cross-coupling capacitive structure configured to vary a third variable positive electric coupling coefficient provided between the resonator R(1,1) and the common connection node H3. The cross-coupling capacitive structure C(NH3) is a variable cross-coupling capacitive structure configured to vary a third variable negative electric coupling coefficient provided between the resonator R(1,1) and the common connection node H3. Thus, a mutual electric coupling coefficient of the resonator R(1,1) is approximately equal to the first variable positive electric coupling coefficient, the third variable positive electric coupling coefficient, the first variable negative electric coupling coefficient and the third variable negative electric coupling coefficient.

With regard to the fourth capacitive voltage divider, the cross-coupling capacitive structure C(PH4) is a variable cross-coupling capacitive structure configured to vary a fourth variable positive electric coupling coefficient provided between the resonator R(1,2) and the common connection node H4. The cross-coupling capacitive structure C(NH4) is a variable cross-coupling capacitive structure configured to vary a fourth variable negative electric coupling coefficient provided between the resonator R(1,2) and the common connection node H4. Thus, a mutual electric coupling coefficient of the resonator R(1,2) is approximately equal to the second variable positive electric coupling coefficient, the fourth variable positive coupling coefficient, the second variable negative coupling coefficient, and the fourth variable negative electric coupling coefficient. Furthermore, the cross-coupling capacitive structure C(12) is a variable cross-coupling capacitive structure configured to vary a second variable intermediate electric coupling coefficient provided between the common connection node H3and the common connection node H4. The first tunable RF filter path66shown inFIG. 26thus has a total mutual coupling coefficient between the resonator R(1,1) and the resonator R(1,2) equal to the sum total of the mutual magnetic coupling coefficient between the inductor208and the inductor212, the mutual electric coupling coefficient of the resonator R(1,1), the mutual electric coupling coefficient of the resonator R(1,2), the first variable intermediate electric coupling coefficient provided between the common connection node H1and the common connection node H2and the second variable intermediate electric coupling coefficient provided between the common connection node H3and the common connection node H4. The double H-bridge structure thus includes two H-bridge structures. The two H-bridge structures allow for common-mode signal transfers of the two H-bridge structures to oppose one another and thereby be reduced and even cancelled.

FIG. 27illustrates still another exemplary embodiment of the first tunable RF filter path66in the first RF filter structure60shown inFIG. 21. While the exemplary embodiment shown inFIG. 27is of the first tunable RF filter path66, any of the tunable RF filter paths shown in the first RF filter structure60ofFIG. 21may be arranged in accordance with the exemplary embodiment shown inFIG. 27. The first tunable RF filter path66shown inFIG. 27includes the same embodiment of the resonator R(1,1) and the same embodiment of the resonator R(1,2) described above with respect toFIG. 22. In addition, the first tunable RF filter path66shown inFIG. 27includes the cross-coupling capacitive structure C(P1) and the cross-coupling capacitive structure (CN1) that form the V-bridge structure described above with respect toFIG. 22. However, the first tunable RF filter path66shown inFIG. 27further includes a resonator R(1,3) and a resonator R(1,4). More specifically, the resonator R(1,3) includes an inductor226, a capacitive structure228, and a capacitive structure230. The resonator R(1,4) includes an inductor232and a capacitive structure234.

With regard to the resonator R(1,3), the inductor226is electrically connected between the capacitive structure228and the capacitive structure230. More specifically, the inductor226has an end236and an end238, which are disposed opposite to one another. The end236is electrically connected to the capacitive structure228and the end238is electrically connected to the capacitive structure230. Both the capacitive structure228and the capacitive structure230are grounded. Thus, the resonator R(1,3) is a differential resonator. In this embodiment, each of the capacitive structure228and the capacitive structure230is a variable capacitive structure.

With regard to the resonator R(1,4), the inductor232and the capacitive structure234are electrically connected in parallel. More specifically, the inductor232has an end240and an end242, which are disposed opposite to one another. The ends240,242are each electrically connected to the capacitive structure234, which is grounded. Thus, the resonator R(1,4) is a single-ended resonator.

In this embodiment, the resonator R(1,1), the resonator R(1,2), the resonator R(1,3), and the resonator R(1,4) are all weakly coupled to one another. The resonator R(1,3) and the resonator R(1,4) are weakly coupled by providing the inductor226and the inductor232such that the inductor226and the inductor232are weakly coupled. The resonators R(1,1), R(1,2), R(1,3), and R(1,4) are each operably associated with one another such that energy transfer factors between the resonators R(1,1), R(1,2), R(1,3), and R(1,4) are less than 10%. Although the resonator R(1,3) and the resonator R(1,4) are weakly coupled, the inductor232has a maximum lateral width and a displacement between the inductor226and the inductor232is less than or equal to half the maximum lateral width of the inductor232. As such, the inductor226and the inductor232are relatively close to one another. The displacement between the inductor226and the inductor232may be measured from a geometric centroid of the inductor226to a geometric centroid of the inductor232. The maximum lateral width may be a maximum dimension of the inductor232along a plane defined by its largest winding. The weak coupling between the inductor226and the inductor232is obtained through topological techniques. For example, the inductor226and the inductor232may be fully or partially aligned, where winding(s) of the inductor226and winding(s) of the inductor232are configured to provide weak coupling through cancellation. Alternatively or additionally, a plane defining an orientation of the windings of the inductor226and a plane defining an orientation of the windings of the inductor232may be fully or partially orthogonal to one another.

In some embodiments, all of the inductors208,212,226,232are provided such that displacements between each of the inductors208,212,226,232are less than or equal to half the maximum lateral width of the inductor212. Alternatively, in other embodiments, only a proper subset of the inductors208,212,226,232has displacements that are less than or equal to half the maximum lateral width of the inductor212. For example, while the displacement between the inductor208and the inductor212may be less than or equal to half the maximum lateral width of the inductor212and the displacement between the inductor226and the inductor232may be less than or equal to half the maximum lateral width of the inductor232, the displacements from the inductor208and the inductor212to the inductor226and the inductor232may each be greater than half the maximum lateral width of the inductor212and half the maximum lateral width of the inductor232.

The inductors208,212,226, and232are magnetically coupled to the each other such that an RF signal received at the end217of the inductor208with a voltage polarity (i.e., either a positive voltage polarity or a negative voltage polarity) results in filtered RF signals with the same voltage polarity being transmitted out the end220of the inductor212, the end236of the inductor226, and the end240of the inductor232. Also, the inductors208,212,226, and232are magnetically coupled to the each other such that an RF signal received at the end240of the inductor232with a voltage polarity (i.e., either a positive voltage polarity or a negative voltage polarity) results in filtered RF signals with the same voltage polarity being transmitted out the end217of the inductor208, the end220of the inductor212, and the end236of the inductor226. This is indicated inFIG. 27by the dot convention where a dot is placed at the end217of the inductor208, a dot is placed at the end220of the inductor212, a dot is placed at the end236of the inductor226, and a dot is placed at the end240of the inductor232.

The first tunable RF filter path66shown inFIG. 27includes a cross-coupling capacitive structure C(P3), a cross-coupling capacitive structure C(N3), a cross-coupling capacitive structure C(P4), and a cross-coupling capacitive structure C(N4) electrically connected between the resonator R(1,2) and the resonator R(1,3). With respect to the resonator R(1,2) and the resonator R(1,3), the cross-coupling capacitive structure C(P3), the cross-coupling capacitive structure C(N3), the cross-coupling capacitive structure C(P4) and the cross-coupling capacitive structure C(N4) are arranged to have the X-bridge structure described above with respect toFIG. 23. Thus, the cross-coupling capacitive structure C(P3) is electrically connected between the end220and the end236so as to provide a variable positive electric coupling coefficient between the resonator R(1,2) and the resonator R(1,3). The cross-coupling capacitive structure C(P3) is a variable cross-coupling capacitive structure configured to vary the variable positive electric coupling coefficient provided between the resonator R(1,2) and the resonator R(1,3). Also, the cross-coupling capacitive structure C(N3) is electrically connected between the end220and the end238so as to provide a variable negative electric coupling coefficient between the resonator R(1,2) and the resonator R(1,3). The cross-coupling capacitive structure C(N3) is a variable cross-coupling capacitive structure configured to vary the variable negative electric coupling coefficient provided between the resonator R(1,2) and the resonator R(1,3).

Additionally, the cross-coupling capacitive structure C(P4) is electrically connected between the end222and the end238so as to provide another variable positive electric coupling coefficient between the resonator R(1,2) and the resonator R(1,3). The cross-coupling capacitive structure C(P4) is a variable cross-coupling capacitive structure configured to vary the other variable positive electric coupling coefficient provided between the resonator R(1,2) and the resonator R(1,3). Finally, the cross-coupling capacitive structure C(N4) is electrically connected between the end222and the end236so as to provide another variable negative electric coupling coefficient between the resonator R(1,2) and the resonator R(1,3). The cross-coupling capacitive structure C(N4) is a variable cross-coupling capacitive structure configured to vary the other variable negative electric coupling coefficient provided between the resonator R(1,2) and the resonator R(1,3).

With respect to the resonator R(1,3) and the resonator R(1,4), the first tunable RF filter path66shown inFIG. 27includes a cross-coupling capacitive structure C(P5) and a cross-coupling capacitive structure C(N5) electrically connected between the resonator R(1,3) and the resonator R(1,4). With respect to the resonator R(1,3) and the resonator R(1,4), the cross-coupling capacitive structure C(P5) and the cross-coupling capacitive structure C(N5) are arranged to have the V-bridge structure described above with respect toFIG. 22. Thus, the cross-coupling capacitive structure C(P5) is electrically connected between the end236and the end240so as to provide a variable positive electric coupling coefficient between the resonator R(1,3) and the resonator R(1,4). The cross-coupling capacitive structure C(P5) is a variable cross-coupling capacitive structure configured to vary the variable positive electric coupling coefficient provided between the resonator R(1,3) and the resonator R(1,4). Also, the cross-coupling capacitive structure C(N5) is electrically connected between the end238and the end240so as to provide a variable negative electric coupling coefficient between the resonator R(1,3) and the resonator R(1,4). The cross-coupling capacitive structure C(N5) is a variable cross-coupling capacitive structure configured to vary the variable negative electric coupling coefficient provided between the resonator R(1,3) and the resonator R(1,4).

The embodiment of first RF filter structure60shown inFIG. 27also includes a cross-coupling capacitive structure C(P6), a cross-coupling capacitive structure C(N6), a cross-coupling capacitive structure C(P7), a cross-coupling capacitive structure C(N7), and a cross-coupling capacitive structure C(P8). With respect to the resonator R(1,1) and the resonator R(1,3), the cross-coupling capacitive structure C(P6) and the cross-coupling capacitive structure C(N6) are each electrically connected between the resonator R(1,1) and the resonator R(1,3). The cross-coupling capacitive structure C(P6) is electrically connected between the end217and the end236so as to provide a variable positive electric coupling coefficient between the resonator R(1,1) and the resonator R(1,3). The cross-coupling capacitive structure C(P6) is a variable cross-coupling capacitive structure configured to vary the variable positive electric coupling coefficient provided between the resonator R(1,1) and the resonator R(1,3). Also, the cross-coupling capacitive structure C(N6) is electrically connected between the end217and the end238so as to provide a variable negative electric coupling coefficient between the resonator R(1,1) and the resonator R(1,3). The cross-coupling capacitive structure C(N6) is a variable cross-coupling capacitive structure configured to vary the variable negative electric coupling coefficient provided between the resonator R(1,1) and the resonator R(1,3).

With respect to the resonator R(1,2) and the resonator R(1,4), the cross-coupling capacitive structure C(P7) and the cross-coupling capacitive structure C(N7) are each electrically connected between the resonator R(1,2) and the resonator R(1,4). The cross-coupling capacitive structure C(P7) is electrically connected between the end220and the end240so as to provide a variable positive electric coupling coefficient between the resonator R(1,2) and the resonator R(1,4). The cross-coupling capacitive structure C(P7) is a variable cross-coupling capacitive structure configured to vary the variable positive electric coupling coefficient provided between the resonator R(1,2) and the resonator R(1,4). Also, the cross-coupling capacitive structure C(N7) is electrically connected between the end222and the end240so as to provide a variable negative electric coupling coefficient between the resonator R(1,2) and the resonator R(1,4). The cross-coupling capacitive structure C(N7) is a variable cross-coupling capacitive structure configured to vary the variable negative electric coupling coefficient provided between the resonator R(1,2) and the resonator R(1,4).

With respect to the resonator R(1,1) and the resonator R(1,4), the cross-coupling capacitive structure C(P8) is electrically connected between the resonator R(1,1) and the resonator R(1,4). The cross-coupling capacitive structure C(P8) is electrically connected between the end217and the end240so as to provide a variable positive electric coupling coefficient between the resonator R(1,1) and the resonator R(1,4). The cross-coupling capacitive structure C(P8) is a variable cross-coupling capacitive structure configured to vary the variable positive electric coupling coefficient provided between the resonator R(1,1) and the resonator R(1,4).

Furthermore, in this embodiment, a variable capacitive structure244is electrically connected in series between the terminal200and the resonator R(1,1). The variable capacitive structure244is configured to vary a variable impedance of the first tunable RF filter path66as measured into the terminal200in order to match a source or a load impedance at the terminal200. In addition, a variable capacitive structure245is electrically connected in series between the resonator R(1,4) and the terminal202. The variable capacitive structure245is configured to vary a variable impedance of the first tunable RF filter path66as seen into the terminal202in order to match a source or a load impedance at the terminal202.

FIGS. 28A through 28Dillustrate different embodiments of the first RF filter structure60, wherein each of the embodiments has different combinations of input terminals and output terminals. The first RF filter structure60can have various topologies. For example, the embodiment of the first RF filter structure60shown inFIG. 28Ahas a single input terminal IN and an integer number i of output terminals OUT1-OUTi. As will be discussed below, the first RF filter structure60may define various tunable RF filter paths (e.g., the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122, and the sixth tunable RF filter path124shown inFIGS. 4, 8, 11, 12, and14-20) that may be used to receive different RF signals at the input terminal IN and transmit a different filtered RF signal from each of the output terminals OUT1-OUTi. As such, the first RF filter structure60shown inFIG. 28Amay be specifically configured to provide Single Input Multiple Output (SIMO) operations.

With regard to the embodiment of the first RF filter structure60shown inFIG. 28B, the first RF filter structure60has an integer number j of input terminals IN1-INjand a single output terminal OUT. As will be discussed below, the first RF filter structure60may define various tunable RF filter paths (e.g., the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122, and the sixth tunable RF filter path124shown inFIGS. 4, 8, 11, 12, and 14-20) that may be used to receive a different RF signal at each of the input terminals IN1-INjand transmit different filtered RF signals from the single output terminal OUT. As such, the first RF filter structure60shown inFIG. 28Bmay be specifically configured to provide Multiple Input Single Output (MISO) operations.

With regard to the embodiment of the first RF filter structure60shown inFIG. 28C, the first RF filter structure60has a single input terminal IN and a single output terminal OUT. As will be discussed below, the first RF filter structure60may define various tunable RF filter paths (e.g., the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122, and the sixth tunable RF filter path124shown inFIGS. 4, 8, 11, 12, and 14-20) that may be used to receive different RF signals at the single input terminal IN and transmit different filtered RF signals from the output terminal OUT. As such, the first RF filter structure60shown inFIG. 28Amay be specifically configured to provide Single Input Single Output (SISO) operations.

With regard to the embodiment of the first RF filter structure60shown inFIG. 28D, the first RF filter structure60has the input terminals IN1-INjand the output terminals OUT1-OUTi. As will be discussed below, the first RF filter structure60may define various tunable RF filter paths (e.g., the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122, and the sixth tunable RF filter path124shown inFIGS. 4, 8, 11, 12, and 14-20) that may be used to receive a different RF signal at each of the input terminal IN1-INjand transmit a different filtered RF signal from each of the output terminals OUT1-OUTi.

FIG. 29illustrates another embodiment of the first RF filter structure60. The first RF filter structure60shown inFIG. 29includes one embodiment of the first tunable RF filter path66and one embodiment of the second tunable RF filter path68. The first tunable RF filter path66includes the resonator R(1,1) and the resonator R(1,2). The resonator R(1,1) and the resonator R(1,2) are thus a first pair of weakly coupled resonators in the first tunable RF filter path66. The second tunable RF filter path68includes the resonator R(2,1) and the resonator R(2,2). The resonator R(2,1) and the resonator R(2,2) are thus a second pair of weakly coupled resonators in the second tunable RF filter path68.

As explained in further detail below, a set S of cross-coupling capacitive structures is electrically connected between the resonator R(1,1), the resonator R(1,2), the resonator R(2,1), and the resonator R(2,2) in the first tunable RF filter path66and the second tunable RF filter path68. More specifically, the set S includes a cross-coupling capacitive structure C(PM1), a cross-coupling capacitive structure C(PM2), a cross-coupling capacitive structure C(PM3), a cross-coupling capacitive structure C(PM4), a cross-coupling capacitive structure C(NM1), and a cross-coupling capacitive structure C(NM2). The set S of cross-coupling capacitive structures interconnects the resonator R(1,1), the resonator R(1,2), the resonator R(2,1), and the resonator R(2,2) so that the first RF filter structure60shown inFIG. 29is a matrix (in this embodiment, a 2×2 matrix) of the resonators R. In alternative embodiments, some of the cross-coupling capacitive structures C(PM1), C(PM2), C(PM3), C(PM4), C(NM1), and C(NM2) may be omitted depending on the filter transfer function to be provided.

Unlike in the embodiment of the first RF filter structure60shown inFIG. 21, in this embodiment, the first tunable RF filter path66and the second tunable RF filter path68are not independent of one another. The set S of cross-coupling capacitive structures thus provides for additional tunable RF filter paths to be formed from the resonator R(1,1), the resonator R(1,2), the resonator R(2,1), and the resonator R(2,2). As discussed in further detail below, the arrangement of the first RF filter structure60shown inFIG. 29can be used to realize examples of each of the embodiments of the first RF filter structure60shown inFIGS. 28A-28D.

The cross-coupling capacitive structure C(PM1) is electrically connected within the first tunable RF filter path66, while the cross-coupling capacitive structure C(PM4) is electrically connected within the second tunable RF filter path68. More specifically, the cross-coupling capacitive structure C(PM1) is electrically connected between the resonator R(1,1) and the resonator R(1,2) in the first tunable RF filter path66. The cross-coupling capacitive structure C(PM1) is a variable cross-coupling capacitive structure configured to provide and vary a (e.g., positive or negative) electric coupling coefficient between the resonator R(1,1) and the resonator R(1,2). The cross-coupling capacitive structure C(PM4) is a variable cross-coupling capacitive structure configured to provide and vary a (e.g., positive or negative) electric coupling coefficient between the resonator R(2,1) and the resonator R(2,2) in the second tunable RF filter path68.

To provide additional tunable RF filter paths, the cross-coupling capacitive structure C(PM2), the cross-coupling capacitive structure C(PM3), the cross-coupling capacitive structure C(NM1), and the cross-coupling capacitive structure C(NM2) are each electrically connected between the first tunable RF filter path66and the second tunable RF filter path68. The cross-coupling capacitive structure C(PM2) is a variable cross-coupling capacitive structure configured to provide and vary a (e.g., positive or negative) electric coupling coefficient between the resonator R(1,2) and the resonator R(2,2). The cross-coupling capacitive structure C(PM3) is a variable cross-coupling capacitive structure configured to provide and vary a (e.g., positive or negative) electric coupling coefficient between the resonator R(1,1) and the resonator R(2,1). The cross-coupling capacitive structure C(NM1) is a variable cross-coupling capacitive structure configured to provide and vary a (e.g., positive or negative) electric coupling coefficient between the resonator R(1,1) and the resonator R(2,2). The cross-coupling capacitive structure C(NM2) is a variable cross-coupling capacitive structure configured to provide and vary a (e.g., positive or negative) electric coupling coefficient between the resonator R(1,2) and the resonator R(2,1).

The first tunable RF filter path66is electrically connected between the input terminal IN1and the output terminal OUT1. In addition, the second tunable RF filter path68is electrically connected between an input terminal IN2and an output terminal OUT2. Accordingly, the first RF filter structure60shown inFIG. 29is an embodiment of the first RF filter structure60shown inFIG. 28D. However, the input terminal IN2and the output terminal OUT1are optional and may be excluded in other embodiments. For example, if the input terminal IN2were not provided, but the output terminal OUT1and the output terminal OUT2were provided, the first RF filter structure60shown inFIG. 29would be provided as an embodiment of the first RF filter structure60shown inFIG. 28A. It might, for example, provide a diplexing or a duplexing function. Furthermore, more than two input terminals or output terminals can be provided. Some examples include embodiments of the first RF filter structure60used for triplexing, quadplexing, herplexing, and providing FDD and carrier aggregation.

The first tunable RF filter path66still provides a path between the input terminal IN1and the output terminal OUT1. However, assuming that the input terminal IN2is not provided for SIMO operation, the cross-coupling capacitive structure C(NM1) is electrically connected between the first tunable RF filter path66and the second tunable RF filter path68to define a first additional tunable RF filter path between the input terminal IN1and the output terminal OUT2. The first additional tunable RF filter path is thus provided by a portion of the first tunable RF filter path66and a portion of the second tunable RF filter path68. More specifically, the first additional tunable RF filter path includes the resonator R(1,1) and the resonator R(2,2). The first additional tunable RF filter path also includes the cross-coupling capacitive structure C(NM1) that is electrically connected between the resonator R(1,1) and the resonator R(1,2). A second additional tunable RF filter path, a third additional tunable RF filter path, a fourth additional tunable RF filter path, and a fifth additional tunable RF filter path are also defined from the input terminal IN1to the output terminal OUT2. The second additional tunable RF filter path includes the resonator R(1,1), the cross-coupling capacitive structure C(PM1), the resonator R(1,2), the cross-coupling capacitive C(PM2), and the resonator R(2,2). Additionally, the third additional tunable RF filter path includes the resonator R(1,1), the cross-coupling capacitive structure C(PM3), the resonator R(2,1), the cross-coupling capacitive C(PM4), and the resonator R(2,2). The fourth additional tunable RF filter path includes the resonator R(1,1), the cross-coupling capacitive structure C(PM1), the resonator R(1,2), the cross-coupling capacitive C(NM2), the resonator R(2,1), the cross-coupling capacitive structure C(PM4), and the resonator R(2,2). Finally, the fifth additional tunable RF filter path includes the resonator R(1,1), the cross-coupling capacitive structure C(PM3), the resonator R(2,1), the cross-coupling capacitive C(NM2), the resonator R(1,2), the cross-coupling capacitive structure C(PM2), and the resonator R(2,2).

If the output terminal OUT1were not provided, but the input terminal IN1and the input terminal IN2were provided, the first RF filter structure60shown inFIG. 29would be provided as an embodiment of the first RF filter structure60shown inFIG. 28B. In this case, the second tunable RF filter path68still provides a path between the input terminal IN2and the output terminal OUT2. However, assuming that the output terminal OUT1is not provided for MISO operation, the first additional tunable RF filter path, the second additional tunable RF filter path, the third additional tunable RF filter path, the fourth additional tunable RF filter path, and the fifth additional tunable RF filter path would provide the paths from the input terminal IN1to the output terminal OUT2.

Finally, if the input terminal IN2and the output terminal OUT2were not provided, the first RF filter structure60shown inFIG. 29would be provided as an embodiment of the first RF filter structure60shown inFIG. 28C. In this case, the second tunable RF filter path68still provides a path between the input terminal IN2and the output terminal OUT2. However, assuming that the output terminal IN1is not provided for MISO operation, the first additional tunable RF filter path, the second additional tunable RF filter path, the third additional tunable RF filter path, the fourth additional tunable RF filter path, and the fifth additional tunable RF filter path would provide the paths from the input terminal IN1to the output terminal OUT2. This may constitute a SISO filter implemented with an array to allow for a large number of signal paths and thus create one or more notches in the transfer function.

With regard to the resonators R(1,1), R(1,2), R(2,1), R(2,2) shown inFIG. 29, the resonators R(1,1), R(1,2), R(2,1), R(2,2) may each be single-ended resonators, differential resonators, or different combinations of single-ended resonators and differential resonators. The resonator R(1,1) and the resonator R(1,2) in the first tunable RF filter path66may each be provided in accordance with any of the embodiments of the resonator R(1,1) and the resonator R(1,2) described above with respect toFIGS. 22-27. For example, the resonator R(1,1) may include the inductor208(seeFIG. 24) and the capacitive structure210(seeFIG. 24). The resonator R(1,2) may include the inductor212and the capacitive structure214(seeFIG. 24). The resonator R(2,1) may include an inductor (like the inductor208inFIG. 24) and a capacitive structure (like the capacitive structure210shown inFIG. 24). The resonator R(2,2) may include an inductor (like the inductor212inFIG. 24) and a capacitive structure (like the capacitive structure214shown inFIG. 24).

Additionally, one or more of the resonators R(1,1), R(1,2) in the first tunable RF filter path66and one or more of the resonators R(2,1), R(2,2) in the second tunable RF filter path68may be weakly coupled. Thus, the resonators R(1,1), R(1,2), R(2,1), R(2,2) may be operably associated with one another such that an energy transfer factor between each of the resonators R(1,1), R(1,2), R(2,1), R(2,2) is less than 10%. Alternatively, the energy transfer factor between only a subset of the resonators R(1,1), R(1,2), R(2,1), R(2,2) is less than 10%. In addition, in at least some embodiments, not all of the resonators R(1,1), R(1,2), R(2,1), R(2,2) are weakly coupled to one another.

In this embodiment, the inductor208(seeFIG. 24) of the resonator R(1,1), the inductor212(seeFIG. 24) of the resonator R(1,2), the inductor of the resonator R(2,1), and the inductor of the resonator R(2,2) may all be weakly coupled to one another. In some embodiments, displacements between the inductor208(seeFIG. 24) of the resonator R(1,1), the inductor212(seeFIG. 24) of the resonator R(1,2), the inductor of the resonator R(2,1), and the inductor of the resonator R(2,2) may all be less than or equal to half the maximum lateral width of the inductor212. Alternatively, in other embodiments, only a proper subset of the inductor208(seeFIG. 24) of the resonator R(1,1), the inductor212(seeFIG. 24) of the resonator R(1,2), the inductor of the resonator R(2,1), and the inductor of the resonator R(2,2) may have displacements that are less than or equal to half the maximum lateral width of the inductor212.

FIG. 30illustrates yet another embodiment of the first RF filter structure60. The first RF filter structure60includes the resonators R described above with respect toFIG. 21. The resonators R of the first RF filter structure60shown inFIG. 30are arranged as a two-dimensional matrix of the resonators R. In this embodiment, the first RF filter structure60includes an embodiment of the first tunable RF filter path66, an embodiment of the second tunable RF filter path68, an embodiment of the third tunable RF filter path110, and an embodiment of the fourth tunable RF filter path112. Thus, the integer M for the first RF filter structure60shown inFIG. 30is four (4) or greater. Additionally, the integer N for the first RF filter structure60shown inFIG. 30is 3 or greater. Note that in alternative embodiments, the integer M may be two (2) or greater and the integer N may be two(2) or greater. It should be noted that in alternative embodiments the number of resonators R in each row and column may be the same or different.

In the embodiment of the first RF filter structure60shown inFIG. 30, the first tunable RF filter path66includes the resonator R(1,1), the resonator R(1,2), and one or more additional resonators R, such as the resonator R(1,N), since the integer N is 3 or greater. All of the weakly coupled resonators R(1,1) through R(1,N) are weakly coupled to one another. Furthermore, the first tunable RF filter path66is electrically connected between a terminal TU1and a terminal TANT1. With regard to the second tunable RF filter path68, the second tunable RF filter path68includes the resonator R(2,1), the resonator R(2,2), and one or more additional resonators R, such as the resonator R(2,N), since the integer N is 3 or greater. All of the weakly coupled resonators R(2,1) through R(2,N) are weakly coupled to one another. Furthermore, the second tunable RF filter path68is electrically connected between a terminal TU2and a terminal TANT2.

With regard to the third tunable RF filter path110, the third tunable RF filter path110includes a resonator R(3,1), a resonator R(3,2), and one or more additional resonators R, such as a resonator R(3,N), since the integer N is 3 or greater. All of the weakly coupled resonators R(3,1) through R(3,N) are weakly coupled to one another. Alternatively, only a proper subset of them may be weakly coupled to one another. Furthermore, the third tunable RF filter path110is electrically connected between a terminal TU3and a terminal TANT3. With regard to the fourth tunable RF filter path112, the fourth tunable RF filter path112includes the resonator R(M,1), the resonator R(M,2), and one or more additional resonators R, such as the resonator R(M,N), since the integer N is 3 or greater. All of the weakly coupled resonators R(M,1) through R(M,N) are weakly coupled to one another. Alternatively, only a proper subset of them may be weakly coupled to one another. Furthermore, the fourth tunable RF filter path112is electrically connected between a terminal TU4and a terminal TANT4.

The first tunable RF filter path66is configured to receive RF signals and output filtered RF signals. It should be noted that the first RF filter structure60may include any number of tunable RF filter paths, such as, for example, the third tunable RF filter path110, the fourth tunable RF filter path112, the fifth tunable RF filter path122, and the sixth tunable RF filter path124, described above with respect toFIGS. 11-14. Each of the resonators R may be a tunable resonator, which allows for a resonant frequency of each of the resonators to be varied to along a frequency range. In alternative embodiments, only a proper subset of the resonators R may be tunable. In still another embodiment, all of the resonators R are not tunable, but rather have a fixed transfer function.

In some embodiments, all of the resonators R in the first RF filter structure60shown inFIG. 30are weakly coupled to one another. Thus, the resonators R may all be operably associated with one another such that energy transfer factors between the resonators R are less than 10%. Alternatively, the energy transfer factor is less than 10% only among a proper subset of the resonators R. In other embodiments, only the resonators R in adjacent tunable RF filter paths66,68,110,112are weakly coupled to one another. For example, all the resonators R(1,1) through R(1,N) may be weakly coupled to all the resonators R(2,1) through R(2,N). In still other embodiments, only subsets of adjacent resonators R may be weakly coupled to each other. For example, the resonators R(1,1), R(1,2) may be weakly coupled to the resonators R(2,1), R(2,2), while the resonators R(3,1), R(3,2) may be weakly coupled to the resonators R(M,1), R(M,2). These and other combinations would be apparent to one of ordinary skill in the art in light of this disclosure.

Sets S(1), S(2), S(3), S(4), S(5), and S(6) of cross-coupled capacitive structures are electrically connected between the resonators R. Each of the sets S(1), S(2), S(3), S(4), S(5), and S(6) is arranged like the set S of cross-coupled capacitive structures described above with respect toFIG. 29. For example, in one particular exemplary embodiment (e.g., when M=4 and N=3), the set S(1) of cross-coupled capacitive structures is electrically connected between the resonators R(1,1), R(1,2) in the first tunable RF filter path66and the resonators R(2,1), R(2,2) in the second tunable RF filter path68. The set S(2) of cross-coupled capacitive structures is electrically connected between the resonators R(1,2), R(1,N) in the first tunable RF filter path66and the resonators R(2,2), R(2,N) in the second tunable RF filter path68. The set S(3) of cross-coupled capacitive structures is electrically connected between the resonators R(2,1), R(2,2) in the second tunable RF filter path68and the resonators R(3,1), R(3,2) in the third tunable RF filter path110. The set S(4) of cross-coupled capacitive structures is electrically connected between the resonators R(2,2), R(2,N) in the second tunable RF filter path68and the resonators R(3,2), R(3,N) in the third tunable RF filter path110. The set S(5) of cross-coupled capacitive structures is electrically connected between the resonators R(3,1), R(3,2) in the third tunable RF filter path110and the resonators R(M,1), R(M,2) in the fourth tunable RF filter path112. Finally, the set S(6) of cross-coupled capacitive structures is electrically connected between the resonators R(3,2), R(3,N) in the third tunable RF filter path110and the resonators R(M,2), R(M,N) in the fourth tunable RF filter path112. Note that some cross-coupled capacitive structures in the sets S(1), S(2), S(3), S(4), S(5), and S(6) of cross-coupled capacitive structures for the resonators R in adjacent columns or in adjacent ones of the tunable RF filter paths66,68,110,112overlap. This is because in the matrix of the resonators R, each of the resonators R is adjacent to multiple other ones of the resonators R. In another embodiment, the sets S(1), S(2), S(3), S(4), S(5), and S(6) of cross-coupled capacitive structures may be connected between non-adjacent resonators R. For example, there may be cross-coupled capacitive structures between resonators R that are more than one column or row apart.

FIG. 31illustrates the embodiment of the first RF filter structure60shown inFIG. 30electrically connected to the first RF antenna16, the second RF antenna32, a third RF antenna246, and a fourth RF antenna247. More specifically, the first tunable RF filter path66is electrically connected to the first RF antenna16at the terminal TANT1. The second tunable RF filter path68is electrically connected to the second RF antenna32at the terminal TANT2. The third tunable RF filter path110is electrically connected to the third RF antenna246at the terminal TANT3. The fourth tunable RF filter path112is electrically connected to the fourth RF antenna247at the terminal TANT4. With the sets S(1), S(2), S(3), S(4), S(5), and S(6) of cross-coupled capacitive structures, the first RF filter structure60shown inFIG. 31forms an interconnected two-dimensional matrix of the resonators R. Thus, in addition to the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, and the fourth tunable RF filter path112, the sets S(1), S(2), S(3), S(4), S(5), and S(6) of cross-coupled capacitive structures provide a multitude of additional tunable RF filter paths between the terminals TU1, TU2, TU3, TU4and the terminals TANT1, TANT2, TANT3, TANT4. It should be noted that in alternative embodiments, the terminals TANT1, TANT2, TANT3, TANT4may not be connected to antennas. Some antennas may be omitted depending on the functionality being realized.

By tuning the sets S(1), S(2), S(3), S(4), S(5), and S(6), the first RF filter structure60shown inFIG. 31can be tuned so that any combination of the resonators R is selectable for the propagation of RF signals. More specifically, the first RF filter structure60shown inFIG. 31is tunable to route RF receive signals from any combination of the terminals TANT1, TANT2, TANT3, TANT4to any combination of the terminals TU1, TU2, TU3, TU4. Additionally, the first RF filter structure60shown inFIG. 31is tunable to route RF transmission signals from any combination of the terminals TU1, TU2, TU3, TU4to the terminals TANT1, TANT2, TANT3, TANT4. Accordingly, the first RF filter structure60can be configured to implement various MIMO, SIMO, MISO, and SISO operations.

FIG. 32illustrates the first RF filter structure60shown inFIGS. 30 and 31with examples of additional tunable RF filter paths248,250highlighted. It should be noted, however, that there are a vast number of additional combinations of the resonators R that may be selected to provide tunable RF filter paths (e.g., the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the additional tunable RF filter path248, and the additional tunable RF filter path250) between the terminals TU1, TU2, TU3, TU4and the terminals TANT1, TANT2, TANT3, TANT4. An explicit description of all of the various combinations of the resonators R that may be implemented with the first RF filter structure60shown inFIGS. 30-32is simply impractical given the high number of possible combinations. Along with the previous descriptions, the additional tunable RF filter paths248,250are highlighted inFIG. 32simply to give examples of the basic concepts. However, the combinations provided for the additional tunable RF filter paths248,250are in no way limiting, as any combination of the resonators R may be selected to route RF signals between the terminals TU1, TU2, TU3, TU4and the terminals TANT1, TANT2, TANT3, TANT4. Any number of functions, such as signal combining, splitting, multiplexing, and demultiplexing, with various filtering profiles for each, may be realized.

With regard to the additional tunable RF filter paths248,250highlighted inFIG. 32, the additional tunable RF filter paths248,250may be used during MIMO, SIMO, MISO, and SISO operations. More specifically, the additional tunable RF filter path248connects the terminal TANT1to the terminal TU2. The additional tunable RF filter path250connects the terminal TANT3to the terminal TU2. As such, the first RF filter structure60may be tuned so that the additional tunable RF filter path248and the additional tunable RF filter path250are selected in a MISO operation from the terminal TANT1and the terminal TANT3to the terminal TU2. The additional tunable RF filter paths248,250may also be used in SIMO operations. For example, the first RF filter structure60may be tuned so that the first tunable RF filter path66and the additional tunable RF filter path248are selected in a SIMO operation from the terminal TU2to the terminal TANT1. The additional tunable RF filter paths248,250can also be used in SISO operations from the terminal TANT1to the terminal TU2or from the terminal TANT3to the terminal TU2. Finally, the additional tunable RF filter paths248,250may also be used in SIMO operations. For instance, the first RF filter structure60may be tuned so that the first tunable RF filter path66and the additional tunable RF filter path250are selected in a SIMO operation from the terminal TANT1to the terminal TU1and from the terminal TANT3to the terminal TU2.

In some applications involving the first RF filter structure60inFIGS. 30-32, MISO and SIMO operations can be used in conjunction with wideband antenna cables or fiber for transmitting RF signals in multiple RF communication frequency bands. Specific communication frequency bands can be processed by certain dedicated RF filtering paths in the first RF filter structure60. For example, different RF signals may be injected from a wideband antenna and then propagated along different dedicated tunable RF filter paths in the first RF filter structure60to the terminals TU1, TU2, TU3, TU4. These dedicated tunable RF filter paths can be configured to have a transfer function that is specifically designed to handle these RF signals. Furthermore, the first RF filter structure60shown inFIGS. 30-32is configured to tune a transfer function of any of the specific tunable RF filter paths (e.g., the first tunable RF filter path66, the second tunable RF filter path68, the third tunable RF filter path110, the fourth tunable RF filter path112, the additional tunable RF filter path248, and the additional tunable RF filter path250) in the first RF filter structure60by tuning resonators R that are not in the specific tunable RF filter path being used to route RF signals. This can help reduce out-of-band noise and reduce insertion losses. It can also improve isolation and out-of-band attenuation.

FIG. 33illustrates yet another embodiment of the first RF filter structure60. The first RF filter structure60includes the resonators R and is arranged as a two-dimensional matrix of the resonators R, where N is equal to four (4) and M is equal to three (3). In this embodiment, the first RF filter structure60includes an embodiment of the first tunable RF filter path66, an embodiment of the second tunable RF filter path68, and an embodiment of the third tunable RF filter path110. It should be noted that in alternative embodiments, the number of resonators R in each row and column may be the same or different.

In the embodiment of the first RF filter structure60shown inFIG. 33, the first tunable RF filter path66includes the resonator R(1,1), the resonator R(1,2), the resonator R(1,3), and the resonator R(1,4). Furthermore, the first tunable RF filter path66is electrically connected between the terminal TU1and the terminal TANT1. With regard to the second tunable RF filter path68, the second tunable RF filter path68includes the resonator R(2,1), the resonator R(2,2), a resonator R(2,3), and a resonator R(2,4). Furthermore, the second tunable RF filter path68is electrically connected between the terminal TU2and the terminal TANT2. With regard to the third tunable RF filter path110, the third tunable RF filter path110includes the resonator R(3,1), the resonator R(3,2), a resonator R(3,3), and a resonator R(3,4). Furthermore, the third tunable RF filter path110is electrically connected between the terminal TU3and the terminal TANT3.

In this embodiment, the resonators R in a subset252of the resonators R(1,1), R(1,2) in the first tunable RF filter path66are weakly coupled to one another. A cross-coupling capacitive structure CS1is electrically connected between the resonators R(1,1), R(1,2). The cross-coupling capacitive structure CS1is a variable cross-coupling capacitive structure configured to vary a variable electric coupling coefficient between the resonators R(1,1), R(1,2). A subset254of the resonators R(1,3), and R(1,4) in the second tunable RF filter path68is also weakly coupled to each other. A cross-coupling capacitive structure CS2is electrically connected between the resonators R(1,3), R(1,4). The cross-coupling capacitive structure CS2is a variable cross-coupling capacitive structure configured to vary a variable electric coupling coefficient between the resonators R(1,3), R(1,4).

As shown inFIG. 33, a unidirectional coupling stage256is electrically connected within the first tunable RF filter path66. The unidirectional coupling stage256defines an amplifier gain and is configured to provide amplification within the first tunable RF filter path66in accordance with the amplifier gain. In some embodiments, the amplifier gain of the unidirectional coupling stage256is a variable amplifier gain. In this embodiment, the unidirectional coupling stage256is electrically connected between the resonator R(1,2) and the resonator R(1,3). The variable amplifier gain can thus control a variable electric coupling coefficient between the resonator R(1,2) in the subset252and the resonator R(1,3) in the subset254. Since the unidirectional coupling stage256is an active semiconductor component, the unidirectional coupling stage256is unidirectional and thus only allows signal propagations from an input terminal IA of the unidirectional coupling stage256to an output terminal OA of the unidirectional coupling stage256. Thus, the resonator R(1,2) in the subset252is unidirectionally mutual electrically coupled to the resonator R(1,3) in the subset254.

Note that the resonators R(1,3), R(1,4) in the subset254are not electrically connected to the second tunable RF filter path68and the third tunable RF filter path110. As such, the unidirectional coupling stage256thus results in a portion of the first tunable RF filter path66with the subset254of the resonators R(1,3), R(1,4) to be unidirectional. Consequently, signal flow can be to the terminal TANT1but not from the terminal TANT1. Since the unidirectional coupling stage256is unidirectional, the variable amplifier gain (and thus the variable electric coupling coefficient between the resonator R(1,2) and the resonator R(1,3)) may be controlled using feed-forward control techniques and/or feedback control techniques.

Next, the resonators R in a subset258of the resonators R(2,1), R(2,2), R(3,1), and R(3,2) in the second tunable RF filter path68and in the third tunable RF filter path110are weakly coupled to one another. An unidirectional coupling stage260is electrically connected between the first tunable RF filter path66and the second tunable RF filter path68. More specifically, the unidirectional coupling stage260is electrically connected between the resonator R(1,1) and the resonator R(2,1). The unidirectional coupling stage260defines an amplifier gain and is configured to provide amplification in accordance with the amplifier gain. In some embodiments, the amplifier gain of the unidirectional coupling stage260is a variable amplifier gain. The variable amplifier gain thus can control a variable electric coupling coefficient between the resonator R(1,1) in the subset252and the resonator R(2,1) in the subset258. A cross-coupling capacitive structure CS3is electrically connected between the resonator R(1,2) and the resonator R(2,2). The cross-coupling capacitive structure CS3is a variable cross-coupling capacitive structure configured to vary a variable electric coupling coefficient between the resonators R(1,2), R(2,2).

To interconnect the resonators R(2,1), R(2,2), R(3,1), and R(3,2), a set S(A) of cross-coupling capacitive structures is electrically connected between the resonators R(2,1), R(2,2), R(3,1), and R(3,2) in the subset258. The set S(A) of cross-coupling capacitive structures is arranged like the set S of cross-coupling capacitive structures described above with respect toFIG. 29. Additionally, the resonators R in a subset262of the resonators R(2,3), R(2,4), R(3,3), and R(3,4) in the second tunable RF filter path68and in the third tunable RF filter path110are weakly coupled to one another. A set S(B) of cross-coupling capacitive structures is electrically connected between the resonators R(2,3), R(2,4), R(3,3), and R(3,4) in the subset262. The set S(B) of cross-coupling capacitive structures is arranged like the set S of cross-coupling capacitive structures described above with respect toFIG. 29.

To interconnect the subset258and the subset262, the first RF filter structure60shown inFIG. 33includes a cross-coupling capacitive structure CS4and a unidirectional coupling stage264. The cross-coupling capacitive structure CS4is electrically connected between the resonators R(2,2), R(2,3). The cross-coupling capacitive structure CS4is a variable cross-coupling capacitive structure configured to vary a variable electric coupling coefficient between the resonators R(2,2), R(2,3). The unidirectional coupling stage264is electrically connected within the third tunable RF filter path110. In this embodiment, the unidirectional coupling stage264is electrically connected between the resonator R(3,3) and the resonator R(3,2). The unidirectional coupling stage264defines an amplifier gain and is configured to provide amplification within the third tunable RF filter path110in accordance with the amplifier gain. In some embodiments, the amplifier gain of the unidirectional coupling stage264is a variable amplifier gain. The variable amplifier gain can thus control a variable electric coupling coefficient between the resonator R(3,3) in the subset262and the resonator R(3,2) in the subset258. Since the unidirectional coupling stage264is an active semiconductor component, the unidirectional coupling stage264is unidirectional and thus only allows signal propagations from an input terminal IB of the unidirectional coupling stage264to an output terminal OB of the unidirectional coupling stage264. Thus, the resonator R(3,3) in the subset262is unidirectionally mutual electrically coupled to the resonator R(3,2) in the subset258. Consequently, the third tunable RF filter path110shown inFIG. 33is unidirectional if the signal flow is between the terminal TANT3and the terminal TU3though the third tunable RF filter path110. As such signal flow between the terminal TANT3and the terminal TU3is provided only through the third tunable RF filter path110, signal flow can only be from the terminal TANT3to the terminal TU3, and not vice versa. In other cases, an additional tunable RF signal path (e.g., the additional RF terminal tunable RF signal path that includes the resonators R(3,1), R(2,2), R(2,3) and R(3,4)) can be tuned to provide bidirectional signal flow between the terminal TU3and the terminal TANT3through the cross-coupling capacitive structure CS4. The unidirectional coupling stages256,260,264may be active devices, such as amplifiers, diodes, transistors, networks of transistors, buffer stages, attenuation stages, and the like. The unidirectional coupling stages256,260,264can have gains higher than one (1), lower than one (1), or equal to one (1). Additionally, the unidirectional coupling stages256,260,264may be passive devices. The unidirectional coupling stages256,260,264may not be entirely or ideally unilateral, but may have some finite reverse coupling. In this case, the unidirectional coupling stages256,260,264may be predominately unilateral. One example in which the unidirectional coupling stages256,260,264may be used for multi-resonator applications and may improve isolation between certain parts, such as transmission ports and receive ports of a duplexer.

FIG. 34illustrates yet another embodiment of the first RF filter structure60. The first RF filter structure60shown inFIG. 34is integrated into an IC package266. The first RF filter structure60shown inFIG. 34includes the resonators R and is arranged as a two-dimensional matrix of the resonators R, where N is equal to three (3) and M is equal to two (2). It should be noted that in alternative embodiments the number of resonators R in each row and column may be the same or different.

In this embodiment, the first RF filter structure60includes an embodiment of the first tunable RF filter path66and an embodiment of the second tunable RF filter path68. The first tunable RF filter path66includes the resonator R(1,1), the resonator R(1,2), and the resonator R(1,3). The second tunable RF filter path68includes the resonator R(2,1), the resonator R(2,2), and the resonator R(2,3). A set S(X) of cross-coupling capacitive structures is electrically connected between the resonators R(1,1), R(1,2), R(2,1), and R(2,2). The set S(X) of cross-coupling capacitive structures is arranged like the set S of cross-coupling capacitive structures described above with respect toFIG. 29. A set S(Y) of cross-coupling capacitive structures is electrically connected between the resonators R(1,2), R(1,3), R(2,2), and R(2,3). The set S(Y) of cross-coupling capacitive structures is also arranged like the set S of cross-coupling capacitive structures described above with respect toFIG. 29.

As shown inFIG. 34, the IC package266houses a package substrate268, a semiconductor die270, and a semiconductor die272. The semiconductor die270and the semiconductor die272are mounted on the package substrate268. In this embodiment, the resonators R of the first RF filter structure60are formed by the package substrate268. The set S(X) of cross-coupling capacitive structures is formed by the semiconductor die270. On the other hand, the set S(Y) of cross-coupling capacitive structures is formed by the semiconductor die272. Thus, the set S(X) of cross-coupling capacitive structures and the set S(Y) of cross-coupling capacitive structures are formed on multiple and separate semiconductor dies270,272. Using the multiple and separate semiconductor dies270,272may be helpful in order to increase isolation. The multiple and separate semiconductor dies270,272may have less area than the semiconductor die268shown inFIG. 34. As such, the embodiment shown inFIG. 35may consume less die area.

FIG. 35illustrates another embodiment of an IC package266′ that houses the same embodiment of the first RF filter structure60described above with regard toFIG. 34. The IC package266′ is the same as the IC package266shown inFIG. 34, except that the IC package266′ only has a single semiconductor die274. In this embodiment, both the set S(X) of cross-coupling capacitive structures and the set S(Y) of cross-coupling capacitive structures are formed by the semiconductor die272. Thus, the IC package266′ allows for a more compact arrangement than the IC package266.

FIG. 36illustrates yet another embodiment of the first RF filter structure60. In this embodiment, the first RF filter structure60is arranged as a three-dimensional matrix of resonators R1, R2, R3. More specifically, a two-dimensional matrix of the resonators R1is provided on a plane k, a two-dimensional array of the resonators R2is provided on a plane m, and a two-dimensional array of the resonators R3is provided on a plane n. Cross-coupling capacitive structures CC are electrically connected between the resonators R1, R2, R3that are adjacent to one another in the same plane k,m,n and in the different planes k,m,n. The three-dimensional matrix of resonators R1, R2, R3thus allows for more resonators to be cross-coupled to one another. This allows for the first RF filter structure60to provide greater numbers of tunable RF filter paths and allows for the first RF filter structure60to be tuned more accurately.

In general, having more tunable RF filter paths allows for the synthesis of a more complex transfer function with multiple notches for better blocker rejection. The number of resonators R1, R2, R3in each of the planes k, n, m may be different or the same. The three-dimensional matrix of resonators can be used in MIMO, SIMO, MISO, and SISO applications.

FIG. 37shows the RF communications circuitry54according to one embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 37is similar to the RF communications circuitry54illustrated inFIG. 4, except in the RF communications circuitry54illustrated inFIG. 37, the RF receive circuitry62, the first tunable RF filter path66, and the second tunable RF filter path68are omitted. Additionally, the RF front-end circuitry58further includes an antenna matching filter600; the first RF filter structure60includes a first tunable RF filter602, which is a first tunable RF transmit filter604in one embodiment of the first tunable RF filter602; and the RF system control circuitry56includes a measurement-based RF spectrum profile606.

In one embodiment of the first RF filter structure60, the RF filter structure60includes the pair of weakly coupled resonators R(1,1), R(1,2) (FIG. 21). Additionally, the first RF filter structure60includes the first connection node70and the first common connection node74. The first tunable RF filter602is directly coupled between the first connection node70and the first common connection node74. The antenna matching filter600is coupled between the first common connection node74and the first RF antenna16, such that the first tunable RF filter602is coupled to the first RF antenna16via the antenna matching filter600. In an alternate embodiment of the RF front-end circuitry58, the antenna matching filter600is omitted, such that the first tunable RF filter602is directly coupled to the first RF antenna16. In another embodiment of the RF front-end circuitry58, the antenna matching filter600includes both filtering circuitry and switching circuitry. In a further embodiment of the RF front-end circuitry58, the antenna matching filter600is replaced with switching circuitry (not shown).

The RF system control circuitry56provides a first filter control signal FCS1and a first filter reconfiguration signal FCS1R to the first tunable RF filter602in general, and to the first tunable RF transmit filter604in particular. In general, the RF communications circuitry54includes control circuitry56,98(FIG. 39), which may be either the RF system control circuitry56or the RF front-end control circuitry98(FIG. 39), that provides the first filter control signal FCS1and the first filter reconfiguration signal FCS1R. In one embodiment of the first filter control signal FCS1, the first filter control signal FCS1is based on the measurement-based RF spectrum profile606. In one embodiment of the first filter reconfiguration signal FCS1R, the first filter reconfiguration signal FCS1R is based on the measurement-based RF spectrum profile606. In an alternate embodiment of the RF communications circuitry54, the first filter reconfiguration signal FCS1R is omitted.

The RF system control circuitry56provides the first transmit signal TX1to the RF transmit circuitry64, which receives and processes the first transmit signal TX1to provide the first upstream RF transmit signal TU1to the first tunable RF filter602via the first connection node70. The first tunable RF transmit filter604receives and filters the first upstream RF transmit signal TU1to provide the first filtered RF transmit signal TF1to the antenna matching filter600via the first common connection node74.

In general, in one embodiment of the first tunable RF filter602, the first tunable RF filter602receives and filters an upstream RF signal to provide a first filtered RF signal, such that a center frequency, which is a tunable center frequency626(FIG. 40B) of the first tunable RF filter602, is based on the first filter control signal FCS1. In one embodiment of the first tunable RF filter602, the first tunable RF filter602is a reconfigurable tunable RF filter602, such that a shape of a transfer function of the first tunable RF filter602is reconfigurable. As such, in one embodiment of the first tunable RF filter602, a configuration of the first tunable RF filter602is based on the first filter reconfiguration signal FCS1R.

FIG. 38shows the RF communications circuitry54according to an alternate embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 38is similar to the RF communications circuitry54illustrated inFIG. 37, except in the RF communications circuitry54illustrated inFIG. 38; the RF transmit circuitry64, the antenna matching filter600, and the first tunable RF transmit filter604are omitted; and the first tunable RF filter602is a first tunable RF receive filter608. Additionally, the RF front-end circuitry58further includes the RF receive circuitry62and RF detection circuitry610. The RF receive circuitry62illustrated inFIG. 38may be similar to the RF receive circuitry62illustrated inFIG. 4. The first tunable RF filter602is directly coupled to the first RF antenna16via the first common connection node74.

The first tunable RF receive filter608receives and filters the first upstream RF receive signal RU1via the first RF antenna16to provide the first filtered RF receive signal RF1to the RF receive circuitry62and to the RF detection circuitry610via the first connection node70. The RF receive circuitry62receives and processes the first filtered RF receive signal RF1to provide the first receive signal RX1to the RF system control circuitry56. Additionally, the RF detection circuitry610receives and detects the first filtered RF receive signal RF1to provide a first detected signal DS1to the RF system control circuitry56.

In one embodiment of the RF detection circuitry610, detection of the first filtered RF receive signal RF1is direct RF detection, which excludes any down-conversion of the first filtered RF receive signal RF1. By using direct RF detection, artifacts created by down-conversion techniques are avoided.

In a first embodiment of the RF communications circuitry54, the RF communications circuitry54is used to create a group of measurements using at least the first detected signal DS1to obtain a profile of an RF communications band612(FIG. 40A) of interest. Therefore, the RF communications circuitry54operates as profiling circuitry to obtain the measurement-based RF spectrum profile606. As such, the measurement-based RF spectrum profile606is based on the group of measurements, which are based on the RF communications band612(FIG. 40A). In one embodiment of the control circuitry56,98(FIG. 39), the control circuitry56,98(FIG. 39) constructs the measurement-based RF spectrum profile606based on the group of measurements. In one embodiment of the RF front-end circuitry58, the RF receive circuitry62is omitted.

In a second embodiment of the RF communications circuitry54, the measurement-based RF spectrum profile606was previously provided to the RF system control circuitry56, and the RF communications circuitry54is used to receive RF signals for normal operations, such as normal RF communications. Therefore, the RF communications circuitry54operates as a slave, which uses a previously defined measurement-based RF spectrum profile606. In one embodiment of the RF front-end circuitry58, the RF detection circuitry610is omitted.

In a third embodiment of the RF communications circuitry54, the RF communications circuitry54is used for both profiling and normal operations. As such, the control circuitry56,98(FIG. 39) selects one of a normal operating mode and a profiling mode. During the profiling mode, the RF detection circuitry610provides at least the first detected signal DS1for the group of measurements, which are used to construct the measurement-based RF spectrum profile606. During the normal operating mode, the first tunable RF filter602receives and filters the upstream RF signal to provide the first filtered RF signal for normal operations. Therefore, the RF communications circuitry54operates autonomously. During the profiling mode, the RF communications circuitry54operates as profiling circuitry to obtain the measurement-based RF spectrum profile606. During the normal operating mode, the RF communications circuitry54operates as a slave, which uses the measurement-based RF spectrum profile606that was obtained during the profiling mode.

In both embodiments of the first tunable RF filter602illustrated inFIGS. 37 and 38in which the first tunable RF filter602is the first tunable RF transmit filter604and the first tunable RF receive filter608, respectively, the center frequency, which is the tunable center frequency626(FIG. 40B) of the first tunable RF filter602, is based on the first filter control signal FCS1. Further, in one embodiment of the first tunable RF filter602, the first tunable RF filter602is the reconfigurable tunable RF filter602, such that the shape of the transfer function of the first tunable RF filter602is reconfigurable. As such, in one embodiment of the first tunable RF filter602, the configuration of the first tunable RF filter602is based on the first filter reconfiguration signal FCS1R.

FIG. 39shows the RF communications circuitry54according to an additional embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 39is similar to the RF communications circuitry54illustrated inFIG. 38, except in the RF communications circuitry54illustrated inFIG. 39, the RF front-end circuitry58further includes the RF front-end control circuitry98and the first detected signal DS1includes a first detected amplitude modulation (AM) signal AM1and a first detected phase modulation (PM) signal PM1. In an alternate embodiment of the first detected signal DS1, the first detected PM signal PM1is omitted.

The RF system control circuitry56provides the front-end control signal FEC to the RF front-end control circuitry98. The RF front-end control circuitry98provides the first filter control signal FCS1and the first filter reconfiguration signal FCS1R to the first tunable RF filter602based on the front-end control signal FEC. The RF front-end control circuitry98provides the front-end status signal FES to the RF system control circuitry56based on the first detected signal DS1. As such, the control circuitry56,98includes the RF system control circuitry56, the RF front-end control circuitry98, or both.

In one embodiment of the RF detection circuitry610, the detection of the first filtered RF receive signal RF1includes AM detection, such that the first detected AM signal AM1is based on the AM detection. In one embodiment of the measurement-based RF spectrum profile606, the measurement-based RF spectrum profile606is based on at least the first detected AM signal AM1.

In an alternate embodiment of the RF detection circuitry610, the detection of the first filtered RF receive signal RF1includes both AM detection and PM detection, such that the first detected AM signal AM1is based on the AM detection and the first detected PM signal PM1is based on the PM detection. In one embodiment of the measurement-based RF spectrum profile606, the measurement-based RF spectrum profile606is based on at least the first detected AM signal AM1and the first detected PM signal PM1.

FIG. 40Ais a graph illustrating a profile of an RF communications band612of interest according to one embodiment of the RF communications band612. The RF communications band612includes a group of active RF signals614, such that each of the group of active RF signals614has a corresponding center frequency616.FIG. 40Bis a graph illustrating a first bandpass filter response624of the first tunable RF receive filter608(FIG. 39) according to one embodiment of the first tunable RF receive filter608(FIG. 39). The first tunable RF receive filter608(FIG. 39) has a tunable center frequency626.

In one embodiment of the RF communications circuitry54(FIG. 39), the first tunable RF receive filter608(FIG. 39) is used to measure and profile the RF communications band612by identifying the active RF signals614in the RF communications band612. The profile is used to develop the measurement-based RF spectrum profile606(FIG. 39) of the RF communications band612. The active RF signals614may be blocking signals in some RF communications systems and desired signals in other RF communications systems. The measurement-based RF spectrum profile606(FIG. 39) may be used to help reject the blocking signals and accept the desired signals.

In this regard, in one embodiment of the control circuitry56,98(FIG. 39), as previously mentioned, the control circuitry56,98(FIG. 39) constructs the measurement-based RF spectrum profile606(FIG. 39) based on the group of measurements, which may be obtained by adjusting the tunable center frequency626for each measurement until the entire RF communications band612has been profiled. As such, in one embodiment of the control circuitry56,98(FIG. 39), at least a portion of the group of measurements is associated with at least a portion of the group of active RF signals614.

In one embodiment of the RF communications band612, the group of active RF signals614includes a pair of somewhat adjacent weak blockers618, a pair of adjacent strong blockers620, and a one-sided strong blocker622. Therefore, the tunable center frequency626of the first tunable RF receive filter608(FIG. 39), the configuration of the first tunable RF receive filter608(FIG. 39), or both may need to be adjusted based on a distribution of the active RF signals614.

FIG. 41Ais a graph illustrating the first bandpass filter response624and a second bandpass filter response628of the first tunable RF receive filter608shown inFIG. 38according to one embodiment of the first tunable RF receive filter608. In general, in one embodiment of the first tunable RF filter602(FIG. 38), the first tunable RF filter602(FIG. 38) has either a first configuration or a second configuration based on the first filter reconfiguration signal FCS1R (FIG. 38). During the first configuration, the first tunable RF filter602(FIG. 38) has the first bandpass filter response624, and during the second configuration, the first tunable RF filter602(FIG. 38) has the second bandpass filter response628. An order of the first tunable RF filter602(FIG. 38) is higher during the second configuration than during the first configuration.

A bandwidth of the second bandpass filter response628is narrower than a bandwidth of the first bandpass filter response624, as shown inFIG. 41A. As such, the first bandpass filter response624may have a lower slope away from the tunable center frequency626than the second bandpass filter response628. Additionally, in the second bandpass filter response628, insertion loss increases more rapidly as the frequency moves away from the tunable center frequency626than the second bandpass filter response628. However, the second bandpass filter response628has increased insertion loss630toward the tunable center frequency626when compared to the first bandpass filter response624. Therefore, the first configuration may be used when blockers are not close to the tunable center frequency626. However, the second configuration may be used when blockers are somewhat close to the tunable center frequency626, such as when the tunable center frequency626is between the somewhat adjacent weak blockers618(FIG. 40A).

FIG. 41Bis a graph illustrating the first bandpass filter response624and a third bandpass filter response632of the first tunable RF receive filter608shown inFIG. 38according to one embodiment of the first tunable RF receive filter608. The first bandpass filter response624is shown for comparison purposes. In general, in one embodiment of the first tunable RF filter602(FIG. 38), the first tunable RF filter602(FIG. 38) has the third bandpass filter response632based on the first filter reconfiguration signal FCS1R (FIG. 38). The third bandpass filter response632includes a left-side notch filter response634and a right-side notch filter response636. As such, the left-side notch filter response634has a tunable left-side notch frequency638and the right-side notch filter response636has a tunable right-side notch frequency640.

A bandwidth of the third bandpass filter response632is narrower than the bandwidth of the first bandpass filter response624, as shown inFIG. 41B. However, the third bandpass filter response632has further increased insertion loss642toward the tunable center frequency626when compared to the first bandpass filter response624. In this regard, the third bandpass filter response632may be used when blockers are strong, close to the tunable center frequency626, or both, such as when the tunable center frequency626is between the adjacent strong blockers620(FIG. 40A).

In an alternate embodiment of the first tunable RF filter602(FIG. 38), the first tunable RF filter602(FIG. 38) has the third bandpass filter response632based on the first filter reconfiguration signal FCS1R (FIG. 38), except that either the left-side notch filter response634or the right-side notch filter response636is omitted. As such, the first tunable RF filter602(FIG. 38) has a bandpass filter response with a side notch filter response. In this regard, the bandpass filter response with a side notch filter response may be used when a strong blocker on one side is close, such as when the tunable center frequency626is close to the one-sided strong blocker622(FIG. 40A). Specifically, in one embodiment of the third bandpass filter response632, the right-side notch filter response636is omitted, such that the third bandpass filter response632has the left-side notch filter response634and not the right-side notch filter response636. Conversely, in an alternate embodiment of the third bandpass filter response632, the left-side notch filter response634is omitted, such that the third bandpass filter response632has the right-side notch filter response636and not the left-side notch filter response634.

FIG. 42shows the RF communications circuitry54according to an alternate embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 42is similar to the RF communications circuitry54illustrated inFIG. 37, except in the RF communications circuitry54illustrated inFIG. 42, the antenna matching filter600is omitted, the RF front-end circuitry58further includes the RF receive circuitry62, and the first RF filter structure60further includes a second tunable RF filter644. The first tunable RF filter602is directly coupled to the first RF antenna16via the first common connection node74, and the second tunable RF filter644is directly coupled to the first RF antenna16via the first common connection node74. In one embodiment of the second tunable RF filter644, the second tunable RF filter644is the first tunable RF receive filter608.

The first tunable RF receive filter608receives and filters a first upstream RF receive signal via the first RF antenna16to provide the first filtered RF receive signal RF1to the RF receive circuitry62via the second connection node72. The RF receive circuitry62receives and processes the first filtered RF receive signal RF1to provide the first receive signal RX1to the RF system control circuitry56.

The RF system control circuitry56provides a second filter control signal FCS2and a second filter reconfiguration signal FCS2R to the second tunable RF filter644in general, and to the first tunable RF receive filter608in particular. In one embodiment of the second filter control signal FCS2, the second filter control signal FCS2is based on the measurement-based RF spectrum profile606. In one embodiment of the second filter reconfiguration signal FCS2R, the second filter reconfiguration signal FCS2R is based on the measurement-based RF spectrum profile606. In an alternate embodiment of the RF communications circuitry54, the second filter reconfiguration signal FCS2R is omitted.

In general, in one embodiment of the second tunable RF filter644, the second tunable RF filter644receives and filters an upstream RF signal to provide a first filtered RF signal, such that a center frequency, which is a tunable center frequency of the second tunable RF filter644, is based on the second filter control signal FCS2. In one embodiment of the second tunable RF filter644, the second tunable RF filter644is a reconfigurable tunable RF filter644, such that a shape of a transfer function of the second tunable RF filter644is reconfigurable. As such, in one embodiment of the second tunable RF filter644, a configuration of the second tunable RF filter644is based on the second filter reconfiguration signal FCS2R.

In one embodiment of the RF communications circuitry54, the measurement-based RF spectrum profile606was previously provided to the RF system control circuitry56, and the RF communications circuitry54is used to receive RF signals and transmit RF signals for normal operations, such as normal RF communications using the measurement-based RF spectrum profile606.

FIG. 43shows the RF communications circuitry54according to an alternate embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 43is similar to the RF communications circuitry54illustrated inFIG. 42, except in the RF communications circuitry54illustrated inFIG. 43, the RF front-end circuitry58further includes the second RF filter structure120, such that the second tunable RF filter644is omitted from the first RF filter structure60and then added to the second RF filter structure120.

FIG. 44shows the RF communications circuitry54according to an additional embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 44is similar to the RF communications circuitry54illustrated inFIG. 38, except in the RF communications circuitry54illustrated inFIG. 44, the RF receive circuitry62is omitted and the first RF filter structure60further includes the second tunable RF filter644and up to and including an NTHtunable RF filter646. Also, the first RF filter structure60further includes up to and including an NTHconnection node648. In one embodiment of the second tunable RF filter644and the second tunable RF receive filter650, the second tunable RF filter644is a second tunable RF receive filter650and the NTHtunable RF filter646is an NTHtunable RF receive filter652.

The RF detection circuitry610provides the first detected signal DS1, a second detected signal DS2, and an NTHdetected signal DSN to the RF system control circuitry56based on receiving and detecting the first filtered RF receive signal RF1, the second filtered RF receive signal RF2and up to and including an NTHfiltered RF receive signal RFN. The RF system control circuitry56provides the first filter control signal FCS1, the second filter control signal FCS2, and up to and including an NTHfilter control signal FCSN to the RF detection circuitry610. Additionally, the RF system control circuitry56provides the first filter reconfiguration signal FCS1R, the second filter reconfiguration signal FCS2R, and up to and including an NTHfilter reconfiguration signal FCSNR to the RF front-end circuitry58.

In general, the first RF filter structure60includes a group of tunable RF filters602,644,646and a group of connection nodes70,72,648. The RF system control circuitry56provides a group of filter control signals FCS1, FCS2, FCSN to the group of tunable RF filters602,644,646to tune the group of tunable RF filters602,644,646. Additionally, the RF system control circuitry56provides a group of filter reconfiguration signals FCS1R, FCS2R, FCSNR to configure the group of tunable RF filters602,644,646. The group of tunable RF filters602,644,646provides a group of filtered RF signals RF1, RF2, RFN to the RF detection circuitry610via the group of connection nodes70,72,648. The RF detection circuitry610receives and detects the group of filtered RF signals RF1, RF2, RFN to provide a group of detected signals DS1, DS2, DSN. The measurement-based RF spectrum profile606is based on a group of measurements using the group of detected signals DS1, DS2, DSN. In one embodiment of the RF detection circuitry610, the RF detection circuitry610includes multiple AM detectors (not shown) and multiple PM detectors (not shown), such that each of the group of detected signals DS1, DS2, DSN has a corresponding detected AM signal and a corresponding detected PM signal.

FIG. 45shows the RF communications circuitry54according to another embodiment of the RF communications circuitry54. The RF communications circuitry54illustrated inFIG. 45is similar to the RF communications circuitry54illustrated inFIG. 43, except in the RF communications circuitry54illustrated inFIG. 45, the RF front-end circuitry58further includes the RF front-end control circuitry98.

The RF front-end control circuitry98provides the first calibration control signal CCS1and up to and including the NTHcalibration control signal CCSN to the first RF filter structure60. The RF front-end control circuitry98provides the PTHcalibration control signal CCSP and up to and including the XTHcalibration control signal CCSX to the second RF filter structure120. Details of the first RF filter structure60and the second RF filter structure120are not shown to simplifyFIG. 45.

The first RF filter structure60provides the first calibration status signal CSS1and up to and including the QTHcalibration status signal CSSQ to the RF front-end control circuitry98. The second RF filter structure120provides the RTHcalibration status signal CSSR and up to and including the YTHcalibration status signal CSSY to the RF front-end control circuitry98. In an alternate embodiment of the RF front-end circuitry58, any or all of the NTHcalibration control signal CCSN, the QTHcalibration status signal CSSQ, the XTHcalibration control signal CCSX, and the YTHcalibration status signal CSSY are omitted.

In one embodiment of the RF front-end circuitry58, the RF front-end circuitry58operates in one of a normal operating mode and a calibration mode. During the calibration mode, the RF front-end control circuitry98performs a calibration of the first RF filter structure60, the second RF filter structure120, or both. As such, the RF front-end control circuitry98provides any or all of the filter control signals FCS1, FCS2, any or all of the filter reconfiguration signals FCS1R, FCS2R, and any or all of the calibration control signals CCS1, CCSN, CCSP, CCSX needed for calibration. Further, the RF front-end control circuitry98receives any or all of the calibration status signals CSS1, CSSQ, CSSR, CSSY needed for calibration.

During the normal operating mode, the RF front-end control circuitry98provides any or all of the filter control signals FCS1, FCS2, any or all of the filter reconfiguration signals FCS1R, FCS2R, and any or all of the calibration control signals CCS1, CCSN, CCSP, CCSX needed for normal operation. Further, the RF front-end control circuitry98receives any or all of the calibration status signals CSS1, CSSQ, CSSR, CSSY needed for normal operation. Any or all of the calibration control signals CCS1, CCSN, CCSP, CCSX may be based on the front-end control signal FEC. The front-end status signal FES may be based on any or all of the calibration status signals CSS1, CSSQ, CSSR, CSSY. Further, during the normal operating mode, the RF front-end circuitry58processes signals as needed for normal operation. Other embodiments described in the present disclosure may be associated with normal operation.

FIG. 46shows the first RF filter structure60shown inFIG. 45according to one embodiment of the first RF filter structure60. The first RF filter structure60includes the first tunable RF filter602and RF filter tuning, configuration, and calibration circuitry654. The RF filter tuning, configuration, and calibration circuitry654is used to facilitate tuning, configuration, and calibration of the first tunable RF filter602. As such, the RF filter tuning, configuration, and calibration circuitry654receives the first filter control signal FCS1and the first filter reconfiguration signal FCS1R. The RF filter tuning, configuration, and calibration circuitry654further receives the first calibration control signal CCS1and up to and including the NTHcalibration control signal CCSN. The RF filter tuning, configuration, and calibration circuitry654provides the first calibration status signal CSS1and up to and including the QTHcalibration status signal CSSQ.

The first tunable RF filter602includes a first resonator656, a second resonator658, a third resonator660, a fourth resonator662, a first coupling circuit664, a second coupling circuit666, a third coupling circuit668, a fourth coupling circuit670, and a fifth coupling circuit672. The first resonator656is coupled to the first connection node70and the second resonator658is coupled to the first common connection node74. In general, the first filter control signal FCS1is used to tune center frequencies of the resonators656,658,660,662and the first filter reconfiguration signal FCS1R is used to configure the coupling circuits664,666,668,670,672to provide connectivity between the resonators656,658,660,662.

In one embodiment of the coupling circuits664,666,668,670,672, each of the coupling circuits664,666,668,670,672may be configured to provide no connectivity or a configurable magnitude of connectivity between two of the resonators656,658,660,662. Further, in one embodiment of the coupling circuits664,666,668,670,672, each of the coupling circuits664,666,668,670,672may be configured to provide either additive or subtractive connectivity between two of the resonators656,658,660,662. In the embodiments that follow, unless stated otherwise, each of the coupling circuits664,666,668,670,672provides no connectivity between the resonators656,658,660,662.

In a first embodiment of the first tunable RF filter602, the first tunable RF filter602has a first configuration based on the first filter reconfiguration signal FCS1R, as illustrated inFIG. 46. In the first configuration, the first coupling circuit664is configured to couple the first resonator656to the second resonator658, thereby providing a first reconfigurable RF filter path674between the first connection node70and the first common connection node74via the first resonator656, the first coupling circuit664, and the second resonator658. A first group of resonators includes the first resonator656and the second resonator658. Therefore, the first group of resonators includes two resonators. In this regard, during the first configuration, the first group of resonators are coupled in series between the first connection node70and the first common connection node74.

FIG. 47shows the first RF filter structure60shown inFIG. 45according to an alternate embodiment of the first RF filter structure60. The first RF filter structure60illustrated inFIG. 47is similar to the first RF filter structure60illustrated inFIG. 46, except in the first RF filter structure60illustrated inFIG. 47, the first tunable RF filter602has a second configuration instead of the first configuration.

As such, in a second embodiment of the first tunable RF filter602, the first tunable RF filter602has the second configuration based on the first filter reconfiguration signal FCS1R, as illustrated inFIG. 47. In the second configuration, the first coupling circuit664provides no connectivity, the second coupling circuit666is configured to couple the first resonator656to the third resonator660, and the third coupling circuit668is configured to couple the third resonator660to the second resonator658, thereby providing a second reconfigurable RF filter path676between the first connection node70and the first common connection node74via the first resonator656, the second coupling circuit666, the third resonator660, the third coupling circuit668, and the second resonator658. A second group of resonators includes the first resonator656, the second resonator658, and the third resonator660. Therefore, the second group of resonators includes three resonators. A first group of coupling circuits includes the second coupling circuit666and the third coupling circuit668. In this regard, during the second configuration, the second group of resonators and the first group of coupling circuits are coupled in series between the first connection node70and the first common connection node74.

The first tunable RF filter602illustrated inFIGS. 46 and 47has a bandpass filter response. However, since the second group of resonators has more resonators than the first group of resonators, an order of the first tunable RF filter602is higher during the second configuration than during the first configuration. Further, during both the first configuration and the second configuration, the first tunable RF filter602has a single path between the first connection node70and the first common connection node74.

FIG. 48shows the first RF filter structure60shown inFIG. 45according to an additional embodiment of the first RF filter structure60. The first tunable RF filter602illustrated inFIG. 48combines the first configuration and the second configuration illustrated inFIGS. 46 and 47, respectively. As such, the first tunable RF filter602illustrated inFIG. 48includes the first reconfigurable RF filter path674and the second reconfigurable RF filter path676. As such, the first reconfigurable RF filter path674and the second reconfigurable RF filter path676share at least one resonator. Further, the first tunable RF filter602includes the first group of resonators and the second group of resonators, such that the first group of resonators is not identical to the second group of resonators. By combining the first reconfigurable RF filter path674and the second reconfigurable RF filter path676, the first tunable RF filter602illustrated inFIG. 48has a bandpass filter response with a side notch filter response.

FIG. 49shows the first RF filter structure60shown inFIG. 45according to another embodiment of the first RF filter structure60. The first tunable RF filter602illustrated inFIG. 49combines the first reconfigurable RF filter path674and the second reconfigurable RF filter path676illustrated inFIG. 48with a third reconfigurable RF filter path678. As such, in a third embodiment of the first tunable RF filter602, the first tunable RF filter602has a third configuration based on the first filter reconfiguration signal FCS1R, as illustrated inFIG. 49. In the third configuration, the first reconfigurable RF filter path674, the second reconfigurable RF filter path676, and the third reconfigurable RF filter path678are provided.

In the third reconfigurable RF filter path678, the fourth coupling circuit670is configured to couple the first resonator656to the fourth resonator662, and the fifth coupling circuit672is configured to couple the fourth resonator662to the second resonator658, thereby providing the third reconfigurable RF filter path678between the first connection node70and the first common connection node74via the first resonator656, the fourth coupling circuit670, the fourth resonator662, the fifth coupling circuit672, and the second resonator658. A third group of resonators includes the first resonator656, the second resonator658, and the fourth resonator662.

As such, the first reconfigurable RF filter path674, the second reconfigurable RF filter path676, and the third reconfigurable RF filter path678share at least one resonator. Further, the first tunable RF filter602includes the first group of resonators, the second group of resonators, and the third group of resonators, such that the first group of resonators is not identical to the second group of resonators, the second group of resonators is not identical to the third group of resonators, and the first group of resonators is not identical to the third group of resonators. By combining the first reconfigurable RF filter path674, the second reconfigurable RF filter path676, and the third reconfigurable RF filter path678, the first tunable RF filter602illustrated inFIG. 49has a bandpass filter response with a left-side notch filter response and a right-side notch filter response.

FIG. 50shows one embodiment of the RF communications circuitry54and alternate RF communications circuitry680. The RF communications circuitry54includes the control circuitry56,98(FIG. 39), which includes the measurement-based RF spectrum profile606. The measurement-based RF spectrum profile606may be useful for configuration of other RF communications systems. As such, the RF communications circuitry54provides the measurement-based RF spectrum profile606to the alternate RF communications circuitry680via an information transfer system682. The information transfer system682may be manual or automated and may include any combination of analog circuitry, digital circuitry, wireless circuitry, communications circuitry, data storage circuitry, the like, or any combination thereof.