CIRCUITS FOR FILTERING RADIO-FREQUENCY SIGNALS

Embodiments of the invention relate to a switching circuit that includes a first signal path for a first frequency range, a second signal path for a second frequency range, and one or more switches. Each of the first and second signal paths may include one or more filters configured to pass a respective region of the first or second frequency ranges. The one or more switches are configured to select one or more signal path filters based on a control signal. Related methods for filtering a radio-frequency signal, radio-frequency modules and wireless devices are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

BACKGROUND

Field

Embodiments of the disclosure relate to the field of wireless communication devices, and more particularly, to front end modules for multiple frequency bands.

Description of the Related Technology

Front-end modules of wireless communication devices are typically configured to condition (for instance, filter and/or amplify) received radio-frequency (RF) signals. The RF signals can be cellular signals, wireless local area network signal (WLAN), e.g., Wi-Fi signals, or the like. Since multiple frequency bands can exist close to each other, the front-end module can be configured to separate frequencies bands adjacent to each other.

Front-end modules can be used for transmitting and/or receiving signals of a wide range of frequencies. For example, a front-end modules can be used to wirelessly communicate RF signals in a frequency range of about 30 kHz to 300 GHz, such as in the range of about such as in the range of about 400 MHz to about 7.125 GHz for Frequency Range 1 (FR1) of the Fifth Generation (5G) communication standard or in the range of about 24.250 GHz to about 71.000 GHz for Frequency Range 2 (FR2) of the 5G communication standard.

Examples of RF communication systems with front-end modules include, but are not limited to, mobile phones, tablets, base stations, network access points, customer-premises equipment (CPE), laptops, and wearable electronics.

SUMMARY

According to one embodiment there is provided a radio-frequency switching circuit for multiple signal bands comprising a first signal path for a first frequency range, a second signal path for a second frequency range, the first and second frequency ranges being adjacent to each other, one or more second signal path filters each configured to pass a respective region of the second frequency range, at least one of the respective regions being smaller than the second frequency range, and one or more switches configured to select one of the second signal path filters based on a control signal.

In one example the first frequency range includes one or more frequency bands used for cellular communication and wherein the second frequency range includes a frequency band used for WLAN communication.

In one example the first frequency range includes a frequency band used for WLAN communication and wherein the second frequency range includes one or more frequency bands used for cellular communication.

In one example the first or second frequency ranges includes a frequency band used for WLAN communication having a frequency range of between 2403 MHz to 2483.5 MHz, or 5150 MHz to 5850 MHz, or 5925 MHz to 7125 MHz.

In one example the first frequency range is separated from the second frequency range by a frequency gap that is smaller than or equal to approximately 15 MHz.

In one example the region of the second frequency range corresponding to the selected second signal path filter is separated from the first frequency range by a frequency gap that is greater than or equal to 20 MHz, 32 MHz, 33 MHz, 37 MHz or 40 MHz.

The one or more second signal path filters can include at least first and second signal path filters configured to pass first and second respective regions of the second frequency range, each of the first and second respective regions being smaller than the second frequency range.

The first frequency range can include a first band lower than the second frequency range and a second band higher than the second frequency range. A lower end of the first region of the second frequency range can be separated from an upper end of the first band of the first frequency range by a frequency gap that is greater than a gap between the upper end of the first band and a lower end of the second frequency range. An upper end of the second region of the second frequency range can be separated from a lower end of the second band of the first frequency range by a frequency gap that is greater than a gap between the lower end of the second band and an upper end of the second frequency range.

In one example a first region of the second frequency range includes frequencies between 2532 MHz to 2463 MHz.

In one example a second region of the second frequency range includes frequencies between 2443 MHz to 2483 MHz.

In one example a third region of the second frequency range includes frequencies between 2423 MHz to 2483 MHz.

Another example further comprises a mode select switch configured to provide the signals from the selected second signal path filter to an output node.

According to another embodiment there is provided a radio-frequency switching circuit comprising a first signal path for a first frequency range, a second signal path for a second frequency range, the first and second frequency ranges being adjacent to each other, one or more first signal path filters each configured to pass a respective region of the first frequency range, at least one of the respective regions of the first frequency range being smaller than the first frequency range, one or more second signal path filters each configured to pass a respective region of the second frequency range, at least one of the respective regions being smaller than the second frequency range, and one or more switches configured to select one or more of the first signal path filters and the second signal path filters based on a control signal.

In one example the first frequency range includes one or more frequency bands used for cellular communication and wherein the second frequency range includes a frequency band used for WLAN communication.

In one example the second frequency range includes a frequency band used for WLAN communication having a frequency range of between 2403 MHz to 2483.5 MHz, or 5150 MHz to 5850 MHz, or 5925 MHz to 7125 MHz.

In one example the first frequency range is separated from the second frequency range by a frequency gap that is smaller than or equal to approximately 15 MHz.

In one example the region of the first frequency range corresponding to the selected first signal path filter is separated from the second frequency range by a frequency gap that is greater than or equal to 20 MHz, 32 MHz, 33 MHz, 37 MHz or 40 MHz.

In one example the region of the second frequency range corresponding to the selected second signal path filter is separated from the first frequency range by a frequency gap that is greater than or equal to 20 MHz, 32 MHz, 33 MHz, 37 MHz or 40 MHz.

The one or more first signal path filters can include at least first and second signal path filters configured to pass first and second respective regions of the first frequency range, each of the first and second respective regions being smaller than the first frequency range. The one or more second signal path filters include at least third and fourth signal path filters configured to pass third and fourth respective regions of the second frequency range, each of the third and fourth respective regions being smaller than the second frequency range. The third and fourth respective regions of the second frequency range can be between a first band of the first frequency range and a second band of the first frequency range.

In one example a first region of the first frequency range includes frequencies between 2300 MHz to 2370 MHz and between 2515 MHz to 2675 MHz.

In one example a first region of the second frequency range includes frequencies between 2532 MHz to 2463 MHz.

In one example a second region of the second frequency range includes frequencies between 2443 MHz to 2483 MHz.

In one example a third region of the second frequency range includes frequencies between 2423 MHz to 2483 MHz.

Another example further comprises a mode select switch for each of the first and second signal paths, each mode select switch configured to provide the signals from the respective signal path filter to a respective output node.

According to another embodiment there is provided a method for filtering a radio-frequency signal comprising receiving a first frequency range and a second frequency range, the first and second frequency ranges being adjacent to each other, providing the first frequency range to a first signal path having one or more first signal path filters that each pass a respective region of the first frequency range, at least one of the respective regions of the first frequency range being smaller than the first frequency range, providing the second frequency range to a second signal path having one or more second signal path filters that each pass a respective region of the second frequency range, at least one of the respective regions being smaller than the second frequency range, and in response to receiving a control signal, selecting one or more of the first signal path filters and the second signal path filters.

According to another embodiment there is provided a radio-frequency module comprising a packaging substrate configured to receive a plurality of components, and a semiconductor die implemented on the packaging substrate, the semiconductor die including a radio-frequency switching circuit comprising a first signal path for a first frequency range, a second signal path for a second frequency range, the first and second frequency ranges being adjacent to each other, one or more second signal path filters each configured to pass a respective region of the second frequency range, at least one of the respective regions being smaller than the second frequency range, and one or more switches configured to select one of the second signal path filters based on a control signal.

According to another embodiment there is provided a wireless device comprising an antenna port coupled to one or more antennas, an antenna switch module, a radio-frequency module, the radio-frequency module including a radio-frequency switching circuit comprising a first signal path for a first frequency range, a second signal path for a second frequency range, the first and second frequency ranges being adjacent to each other, one or more second signal path filters each configured to pass a respective region of the second frequency range, at least one of the respective regions being smaller than the second frequency range, and one or more switches configured to select one of the second signal path filters based on a control signal, and a controller configured to provide a control signal to the radio-frequency switching circuit.

DETAILED DESCRIPTION

Aspects and embodiments described herein are directed to a switching circuit for filtering radio-frequency signals in two adjacent frequency ranges. The switching circuit may select a filter path to provide a sub-range of frequencies for at least one of the frequency ranges. This can advantageously enables a larger frequency separation between signals in the first frequency range and signals in a second frequency range thereby attenuating emissions and insertion loss and improving the coexistence of both signals on a transmission line as further described below.

Shared use of antennas is often facilitated in existing radio architectures through the use of “antenna plexers”, which include banks of filters that enable a filtered merge of many signals in different frequency ranges to a single common antenna feed for a broadband antenna supporting all those bands. These are implemented in a variety of filter technologies, such as low temperature co-fired ceramic technology (LTCC), integrated passive device technology (IPD), discrete surface-mount technology (SMT), or a combination of those for purely L-C-based filters. As the filter band groups of these ganged band pass filters get closer together in frequency offset, the corner frequency roll-off of the band pass filters, which designed in-band from out-of-band (OOB), starts to have more impact in increasing in-band insertion loss at the band edges, and the loading loss of the filters becomes worse as well as the band pass filters move closer together in frequency.

Typically, wireless communication frequencies can be divided into a low frequency band (e.g., approximately 698 MHz-approximately 960 MHz, LB), a middle frequency band (e.g., approximately 1427 MHz-approximately 2200 MHz, MB), a high frequency band (e.g., approximately 2300 MHz-approximately 2690 MHz, HB) and ultrahigh frequency band (e.g., approximately 3400 MHz-approximately 3600 MHz, UHB). The frequency bands may be cellular frequency bands, such as UMTS (Universal Mobile Telecommunications System) frequency bands described below in Table 1, or other non-UMTS frequency bands.

The high frequency band includes, but is not limited to, Band 40 (B40), Band 30 (B30), Band 41 (B41) and Band 7 (B7), etc. B41 is used in time division duplex (TDD) and thus has a single frequency band of approximately 2496 MHz to approximately 2690 MHz, which is utilized for both transmitted (Tx) and received (Rx) operations. Similarly, B40 is used in TDD and thus has a single frequency band of approximately 2300 MHz to approximately 2400 MHz. B41 and B40 can be utilized in cellular communications, e.g., 3rd generation partnership project (3GPP) wireless device. B7 is used in frequency division duplex (FDD) and thus performs simultaneous Tx and Rx operations via different frequencies, for example, Tx (approximately 2500 MHz to approximately 2570 MHz) and Rx (approximately 2620 MHz to approximately 2690 MHz) paths. This is typically accomplished by the use of a duplexer, which combines the Tx and Rx paths into a common terminal. B30 is also used in FDD and thus performs simultaneous Tx and Rx operations via different frequencies, for example, Tx (approximately 2305 MHz to approximately 2315 MHz) and Rx (approximately 2350 MHz to approximately 2360 MHz) paths.

FIG.1illustrates an example of frequency bands that can be utilized in wireless communications, according to certain embodiments. For illustration purposes, the frequency range of approximately 1710 MHz to approximately 2400 MHz is illustrated as MB/HB 1 and the frequency range of approximately 2496 MHz to approximately 2690 MHz is illustrated as HB 2 inFIG.1. Band B40 has a frequency range of approximately 2300 MHz to 2400 MHz, and Band B41 has a frequency range of approximately 2496 MHz to 2690 MHz. As illustrated inFIG.1, a frequency gap between an upper channel of the MB/HB 1 band (specifically, an upper channel of B40) and a lower channel of Wi-Fi and is approximately 3 MHz. A frequency gap between an upper channel of Wi-Fi and a lower channel of the HB 2 band (specifically, B41) is approximately 13 MHz.

It will be appreciated that although the specific examples described herein relate to enabling the coexistence between 2.4 GHz Wi-Fi signals and adjacent frequency bands B40 and B41, features of the disclosure are not limited to such examples and may be applied to other adjacent frequency bands, e.g., to other Wi-Fi signals and their corresponding adjacent frequency bands. For example, similar principles may be applied when using the 5 GHz Wi-Fi band (ranging from approximately 5.15 GHz to approximately 5.85 GHz) and adjacent frequency band n79 (approximately 4.4 GHz to approximately 5.00 GHz), where the 5 GHz Wi-Fi band is separated from the n79 band by a frequency gap of approximately 15 MHz, or when using the 6 GHz Wi-Fi band (approximately 5.925 GHz to approximately 7.125 GHz) and adjacent frequency band B47 (approximately 5.855 GHz to 5.925 GHz), where there is effectively no frequency gap between the 6 GHz Wi-Fi band and the B47 band.

The implementation of the combination of Wi-Fi and cellular bands can be quite difficult on shared antenna systems that support both radio access technologies (RATs). This is because the frequency gap between these bands becomes quite small, as described above, such that the 2.4 GHz Wi-Fi is in extremely close proximity to the HB group, which includes bands both above (for example B41) and below (for example B40) the 2.4 GHz Wi-Fi band. Emissions and isolation between these bands for these RATs is a large challenge for attenuation, isolation, emissions and insertion loss. In particular, emissions due to an Adjacent Channel Leakage Ratio (ACLR), Spectrum Emission Mask (SEM) and out-of-band emissions should in certain cases be attenuated by more than approximately 35 to 40 dB to mitigate receive desense (RxDeSense) of the other RATs.

Some configurations use ganged band-pass filters in antenna plexers to facilitate isolation and merging of the various bands on to the common single antenna feed. An example switching circuit200is shown in the schematic diagram ofFIG.2, which can be implemented in, but is not limited to, a front end module, a front end configuration, a diversity receiver module, a multiple input multiple output (MiMo) module, etc.

The switching circuit200ofFIG.2comprises antennas202,204coupled to an antenna port, an antenna switch206which may be implemented on an antenna switching module (ASM), ganged filters212,214,218, and control signal208. The switching circuit200is configured to transmit an RF transmit signal to antennas202,204, receive an RF receive signal from the antennas202,204, and route the RF receive signal to receive circuitry such as the ganged pass-band filters212,214,218for subsequent downconversion and baseband processing. The RF receive signal may be received as an FDD signal and/or a TDD signal, and have a specific frequency band configuration. For example, the signals may include single-band signals having data modulated onto a single frequency band, multi-band signals (also referred to as inter-band carrier aggregation signals) having data modulated onto multiple frequency bands and/or data modulated onto multiple frequency bands using different communication protocols.

In the illustrated embodiment, the antenna switch206is configured to receive an antenna swapping signal through the control signal208from a baseband subsystem that includes a processor and/or is based at least in part on the frequency band configuration. The antenna switch206is configured to connect the appropriate antenna(s)202,204with ganged filters212,214,218based on the antenna swapping signal. Further, a sounding reference signal (SRS) is transmitted to a base station through at least one of the antennas202,204. The base station may use the SRS for uplink frequency selective scheduling, such as SRS hopping supporting to be able to direct transmit signals to appropriate antennas202,204. The connection paths of the antenna switch206illustrated inFIG.2are for illustrative purposes only. The antenna switch206shown in the example ofFIG.2may not be present in some other configurations. However, the use of antenna switch206can enable integration of post-antenna plexer switching.

The RF signals can include at least one of TDD and/or FDD signal. The switching circuit200utilizes a filter212for filtering LB signals transmitted to and received from at least one of the antennas202,204. The switching circuit200utilizes a filter214for filtering MB/HB signals transmitted to and received from at least one of the antennas202,204. In an embodiment, filter214comprises a ganged MB band pass filter and an HB band pass filter. In an alternative embodiment, filter214may be a dual-band filter configured to pass both MB band frequencies and HB band frequencies. In an embodiment, the MB comprises a frequency range of approximately 1710 MHz to approximately 2400 MHz and the HB comprises a frequency range of approximately 2496 MHz to approximately 2690 MHz. The switching circuit200utilizes a filter218for filtering the 2.4 GHz Wi-Fi band signals transmitted to and received from at least one of the antennas202,204.

In an embodiment, the filters214,218can comprise band pass filter(s), whereas the filter212can comprise a low pass filter. The filters212,214,218can comprise surface acoustic wave (SAW) filters and/or bulk acoustic wave (BAW) filters. SAW and/or BAW devices utilize the piezoelectric effect to convert energy back and forth between the electrical and mechanical realms where the presence of an electrical field causes the material to deform and the application of a mechanical stress induces an electric charge.

As indicated above, it can be challenging to sufficiently attenuate OOB signals without suffering band edge insertion loss degradation for frequency bands that are in close proximity, such as where high frequency band B40 is relatively close to the low end of a 2.4 GHz Wi-Fi band and B41 is relatively close to the high end of the 2.4 GHz Wi-Fi band.

Embodiments of the disclosure mitigate such problems by providing a switching circuit that can reduce the operational bandwidth of the Wi-Fi and/or cellular RF bands to reduce insertion loss and improve isolation, as further described below.

A first embodiment of the disclosure enables reduced bandwidth for Wi-Fi signals by selecting either a high channel Wi-Fi band or a low channel Wi-Fi band.

FIG.3illustrates an example of how the 2.4 GHz Wi-Fi frequency band may be divided into two regions partially overlapping each other. In the illustrated embodiment, the full Wi-Fi band spanning frequencies from 2403 MHz to 2483 MHz can be divided into two overlapping regions, Wi-Fi A and Wi-Fi B. In one aspect, the overlapping region can support at least a 20 MHz bandwidth channel. For example, Wi-Fi A can have a range of approximately 2403 MHz to 2463 MHz and Wi-Fi B can have a range of approximately 2443 MHz to 2483 MHz. In another aspect, the overlapping region can support at least a 40 MHz bandwidth channel. For example, Wi-Fi A can have a range of approximately 2403 MHz to 2463 MHz and Wi-Fi B can have a range of approximately 2423 MHz to 2483 MHz. The ranges of Wi-Fi A, Wi-Fi B and the overlapping region can vary based on the Wi-Fi standard or required channel bandwidth. Separating the full Wi-Fi band into sub-bands Wi-Fi A and Wi-Fi B facilitates a larger gap between an upper channel of the MB/HB 1 band (B40) and a lower channel of Wi-Fi band (sub-band Wi-Fi B), and a larger gap between an upper channel of Wi-Fi (sub-band Wi-Fi A) and a lower channel of the HB 2 band (B41, or B7 Tx), as shown inFIGS.4A and4B.

FIG.4Aillustrates an example of a frequency band configuration of B40 and sub-band Wi-Fi B without Wi-Fi A, B7 and B41. In this configuration, a gap between B40 and Wi-Fi B is approximately 20 MHz (when Wi-Fi B is selected as approximately 2423 MHz to 2483 MHz) or approximately 40 MHz (when Wi-Fi B is selected as approximately 2443 MHz to 2483 MHz). The gap between B40 and Wi-Fi B can vary depending on the division of the Wi-Fi band.FIG.4Billustrates an example of a frequency band configuration of B41 and/or B7 Tx and sub-band Wi-Fi A without B40 and Wi-Fi B. In this configuration, a gap between B41 and Wi-Fi A is approximately 33 MHz and a gap between B7 Tx and Wi-Fi A is approximately 37 MHz. These band configurations provide a frequency offset gap that is larger than 3 MHz, resulting in better out of band attenuation and lower in-band insertion loss.

Accordingly, the 2.4 GHz Wi-Fi band may be split into two overlapping frequency regions which may each be provided with separate RF filter paths. The frequency overlap is variable and dependent on the implementation, but can support at least 20 MHz channel placements, and potentially 40 MHz channels as illustrated inFIG.4A. This depends on the Wi-Fi a/b/g/n/x standard that is supported by the implementation. Advantageously, splitting the Wi-Fi band into two regions (region “A” with excellent performance for the lower Wi-Fi 2.4 GHz channels, and region “B” with excellent performance for the upper Wi-Fi 2.4 GHz channels) provides that each respective filter is narrower in bandwidth, but also provides better OOB attenuation, lower in-band insertion loss (IL), and also provides a larger gap in frequency offset between its band edges and the cellular bands.

FIG.5is a schematic diagram of an embodiment of a switching circuit500configured to enable a signal to be routed through certain combinations of switches. The switching circuit500can be implemented in, but not limited to, a front end module, a front end configuration, a diversity receiver module, a multiple input multiple output (MiMo) module, etc.

In the illustrated embodiment, the switching circuit500comprises antennas202,204, a filtering circuit500A comprising ASM206, control signal208, LB filter212, and MB/HB214filters as described above. The filtering circuit500A further comprises two Wi-Fi filters512,514for filtering the 2.4 GHz Wi-Fi band signals transmitted to and received from at least one of the antennas202,204. Each filter512,514is implemented on a respective Wi-Fi signal path522,524that each includes a switch532,534for selecting one or more of the Wi-Fi signal paths. Advantageously, switches532,534also enable filters512,514to be completely disconnected when Wi-Fi is not concurrently active thereby enabling much lower insertion loss due to the reduced loading of filters212,214.

Switching circuit500further comprises a Wi-Fi band select switch542that provides either the Wi-Fi A signal or Wi-Fi B signal to an output node on Wi-Fi signal path552, and in some embodiments the Wi-Fi band select switch542can be a single-pole/multiple-throw (SPMT) switch as shown inFIG.5. A control signal (not shown) determines the configuration of the switches532,534and the Wi-Fi band select switch542in order to provide either the Wi-Fi A signal or the Wi-Fi B signal to the Wi-Fi signal path552.

In the embodiment shown, the first filter512is configured to filter the low channel Wi-Fi band, e.g., Wi-Fi A having a range of approximately 2403 MHz to 2463 MHz, and the second filter514is configured to filter the high channel Wi-Fi band, e.g., Wi-Fi B having a range of approximately 2443 MHz to 2483 MHz or a range of approximately 2423 MHz to 2483 MHz. Switches532,534are configured to switch-combine the appropriate Wi-Fi filter512,514with the cellular LB filter212and/or cellular MB/HB filter214according to the received cellular frequency band and desired band separation, as described above. In some embodiments, the switches532,534are implemented on the ASM206.

In the embodiment shown inFIG.5, the filters212,214are implemented as ganged filters on a single switchless LB/MB/HB signal path while filters512,514are implemented in separate signal paths that may be connected in parallel to the main LB/MB/HB signal path via switch532and switch534respectively. This configuration can prevent loading of the cellular RF signals by the Wi-Fi signals. However, it will be appreciated that in alternative embodiments each of the cellular filters212,214and Wi-Fi filters512,514may be provided on separate signal paths having respective switches to route a receive signal to at least one of the plurality of signal paths corresponding to the frequency band of the single-band or multi-band receive signal. In such embodiments, the Wi-Fi band select switch542is not included.

A second embodiment of the disclosure enables the use of a reduced bandwidth of cellular RF signals.

As discussed above, B40 and B41 are commonly used high frequency bands that coexist very close to the 2.4 GHz Wi-Fi band frequency range.FIG.6illustrates the relative separation between the 2.4 GHz Wi-Fi band and the conventional B40 and B41 bands as well as the relative separation between the 2.4 GHz Wi-Fi band and sub-bands B40A and B41N. As shown inFIG.6, the 2.4 GHz Wi-Fi band has a frequency range of 2403 MHz to 2483 MHz, band B40 has a frequency range of 2300 MHz to 2400 MHz, and B41 has a frequency range of 2496 MHz to 2690 MHz. The gap between a lower channel of the Wi-Fi band and an upper channel of Band B40 is 3 MHz, and a gap between an upper channel of the Wi-Fi band and a lower channel of Band B41 is 13 MHz. As also shown inFIG.6, Band B40A has a frequency range of 2300 MHz to 2370 MHz and Band B41N has a frequency range of 2515 MHz to 2675 MHz. Accordingly, a gap between a lower channel of Wi-Fi and an upper channel of B40A is 33 MHz, and a gap between an upper channel of Wi-Fi and a lower channel of B41N is 32 MHz.

As indicated above, using a band configuration of B40 and B41 with the 2.4 GHz Wi-Fi band results in a relatively small frequency offset gap of 3 MHz and 13 MHz respectively. However, the use of reduced bandwidth cellular bands B40A and B41N can provide a larger gap in frequency offset, resulting in better out of band attenuation and lower in-band insertion loss.

FIG.7is a schematic diagram of an embodiment of a switching circuit700configured to enable a signal to be routed through certain combinations of switches. The switching circuit700can be implemented in, but not limited to, a front end module, a front end configuration, a diversity receiver module, a multiple input multiple output (MiMo) module, etc.

In the illustrated embodiment, the switching circuit700comprises antennas202,204, filtering circuit700A comprising ASM206, control signal208, LB cellular filter212and a 2.4 GHz Wi-Fi filter218as described above. The filtering circuit700A further comprises two cellular filters712,714for filtering the MB and HB signals transmitted to and received from at least one of the antennas202,204. Each filter712,714is implemented on a respective cellular signal path722,724that each includes a switch732,734for selecting one or more of the cellular signal paths. Advantageously, switches732,734also enable filters512,514to be completely disconnected when MB/HB cellular signals are not active thereby enabling much lower insertion loss due to the reduced loading of filters212,218.

The switching circuit700further comprises a cellular band select switch742that provides the output from either filter712or714to an output node on cellular MB/HB signal path752. Accordingly, the cellular band select switch742provides either a first, full bandwidth, RF signal MHB1 or a second, reduced bandwidth, RF signal MHB2 to the cellular signal path752. In some embodiments, the first filter712is configured to pass frequencies in the range of between 1710 MHz to 2400 MHz and between 2496 MHz to 2690 MHz while the second filter714is configured to pass a reduced frequency range of between 1710 MHz to 2370 MHz and between 2515 MHz to 2675 MHz. In some embodiments, the first filter712is configured to filter at least bands B40 and B41 while the second filter714is configured to filter sub-bands B40A and B41N.

Switches732,734are configured to switch-combine the appropriate MB/HB filter712,714with the cellular LB filter212and 2.4 GHz Wi-Fi filter218according to whether the Wi-Fi band is being used and the desired band separation. In some embodiments the cellular band select switch742can be a single-pole/multiple-throw (SPMT) switch, as shown inFIG.7. A control signal (not shown) may determine the configuration of the switches732,734and the cellular band select switch in order to provide either the full bandwidth (e.g. B40 and B41) signal or the reduced bandwidth (e.g. B40A and B41N) signal to the cellular signal path752.

In the embodiment shown inFIG.7, the filters212,218are implemented as switchless signal paths while filters712,714are implemented in separate signal paths that may be connected in parallel to the LB signal path and Wi-Fi signal path via switches732,734respectively. This configuration can prevent loading of the Wi-Fi signals by the cellular HB signals. However, it will be appreciated that in alternative embodiments each filter may be implemented on a separate signal path having a respective switch to route a receive signal to at least one of the plurality of signal paths that corresponds to the frequency band of the single-band or multi-band receive signal. In such embodiments, the cellular band select switch742is not included.

A third embodiment of the disclosure enables the reduction in bandwidth of either or both Wi-Fi and cellular RF signals.

FIG.8is a schematic diagram of an embodiment of a switching circuit800comprising antennas202,204, filtering circuit800A comprising ASM206, control signal208and LB cellular filter212as described above. The filtering circuit800A further comprises two Wi-Fi filters512,514for filtering the 2.4 GHz Wi-Fi band signals and two cellular filters712,714for filtering the MB and HB signals transmitted to and received from at least one of the antennas202,204.

As described above, each filter512,514,712,714is implemented on a respective cellular signal path522,524,722,724that each includes a switch532,534,732,734for selecting one or more of the Wi-Fi or cellular signal paths. A Wi-Fi band select switch542provides either the Wi-Fi A signal or Wi-Fi B signal to a Wi-Fi signal path552while a cellular band select switch742provides either the full bandwidth MB/HB signal band (e.g. bands B40 and B41) or a reduced bandwidth MB/HB signal (e.g. sub-bands B40A and B41N) to cellular MB/HB signal path752. Although filter212is implemented as a switchless signal path it will be appreciated that in alternative embodiments each filter may be implemented on a separate signal path having a respective switch to route a receive signal to at least one of the plurality of signal paths that corresponds to the frequency band of the single-band or multi-band receive signal.

The third embodiment advantageously enables optimization of the insertion loss and attenuation by selecting the appropriate Wi-Fi and/or cellular band signal path.

FIG.9shows an example method900that can be implemented by a switching circuit to filter received radio-frequency signals as described herein. In a first step902the process starts. In a second step904the switching circuit filters a first frequency range with a first filter. In a third step906the switching circuit filters a first region of the first frequency range with a second filter. In a fourth step908the switching circuit filters a second frequency range with a third filter. In a fifth step910the switching circuit selects the first filter or the second filter based on a control signal using one or more switches. The process ends at a final step912.

FIG.10Ais an exemplary block diagram of switching module1000. In the illustrated embodiment, a multimode semiconductor die1002can include one or more of the switching circuits500,700,800ofFIGS.5,7, and8respectively, that include filtering circuits500A,700A and800A and switches552,752.FIG.10Bis an exemplary block diagram of a multi-chip switching module1010. In an embodiment, filter circuits500A,700A and800A may be implemented on a filter die1012while switches552,752may be implemented on switch die1014.FIG.10Cis an exemplary block diagram of a multi-chip switching module1020including the switch die1014and a plurality of SAW or BAW filters1022, which can form some or all of the filters in the filter circuits500A,700A,800A. The multi-chip module1020can further include power amplifier (PA) circuitry1024.

The modules1000,1010,1020can further include connectivity1032to provide signal interconnections, packaging1034, such as for example, a package substrate, for packaging of the circuitry, and other circuitry die1036, such as, for example amplifiers, pre-filters, post filters modulators, demodulators, down converters, and the like, as would be known to one of skill in the art of semiconductor and multi-chip module fabrication in view of the disclosure herein.

FIG.11is an exemplary block diagram illustrating a simplified wireless device1100. The wireless device1100can include one or more of the switching circuits500,700,800ofFIGS.5,7, and8, respectively, for example.

The wireless device1100includes a speaker1102, a display1104, a keyboard1106, and a microphone1108, all connected to a baseband subsystem1110. A power source1142, which may be a direct current (DC) battery or other power source, is also connected to the baseband subsystem1110to provide power to the wireless device1100. In a particular embodiment, the wireless device1100can be, for example but not limited to, a portable telecommunication device such as a mobile cellular-type telephone. The speaker1102and the display1104receive signals from baseband subsystem1110, as known to those skilled in the art. Similarly, the keyboard1106and the microphone1108supply signals to the baseband subsystem1110. The baseband subsystem1110includes a microprocessor (μP)1120, memory1122, analog circuitry1124, and a digital signal processor (DSP)1126in communication via bus1128. Bus1128, although shown as a single bus, may be implemented using multiple busses connected as necessary among the subsystems within the baseband subsystem1110. The baseband subsystem1110may also include one or more of an application specific integrated circuit (ASIC)1132and a field programmable gate array (FPGA)1130.

The microprocessor1120and memory1122provide the signal timing, processing, and storage functions for wireless device1100. The analog circuitry1124provides the analog processing functions for the signals within baseband subsystem1110. The baseband subsystem1110provides control signals to a transmitter1150, a receiver1170, a power amplifier1180, and a switching module1190, for example.

It should be noted that, for simplicity, only the basic components of the wireless device1100are illustrated herein. The control signals provided by the baseband subsystem1110control the various components within the wireless device1100. Further, the function of the transmitter1150and the receiver1170may be integrated into a transceiver.

The baseband subsystem1110also includes an analog-to-digital converter (ADC)1134and digital-to-analog converters (DACs)1136and1138. In this example, the DAC1136generates in-phase (I) and quadrature-phase (Q) signals1140that are applied to a modulator1152. The ADC1134, the DAC1136, and the DAC1138also communicate with the microprocessor1120, the memory1122, the analog circuitry1124, and the DSP1126via bus1128. The DAC1136converts the digital communication information within baseband subsystem1110into an analog signal for transmission to the modulator1152via connection1140. Connection1140, while shown as two directed arrows, includes the information that is to be transmitted by the transmitter1150after conversion from the digital domain to the analog domain.

The transmitter1150includes the modulator1152, which modulates the analog information on connection1140and provides a modulated signal to upconverter1154. The upconverter1154transforms the modulated signal to an appropriate transmit frequency and provides the upconverted signal to the power amplifier1180. The power amplifier1180amplifies the signal to an appropriate power level for the system in which the wireless device1100is designed to operate.

Details of the modulator1152and the upconverter1154have been omitted, as they will be understood by those skilled in the art. For example, the data on connection1140is generally formatted by the baseband subsystem1110into in-phase (I) and quadrature (Q) components. The I and Q components may take different forms and be formatted differently depending upon the communication standard being employed.

The power amplifier1180supplies the amplified signal to a front-end module1162, where the amplified signal is conditioned and filtered by one or more signal conditioning filters for transmission. The front end module1162comprises an antenna system interface that may include, for example, the switching circuit1190configured to switch a signal between the antenna1160, the receiver1170, and the power amplifier1180(receiving the RF transmit signal from the transmitter1150), as described herein to implement FDD and TDD in a shared band. For example, the switching circuit1190can include one or more of the switching circuits500,700,800ofFIGS.5,7, and8, respectively. The RF transmit signal is supplied from the front-end module1162to the antenna1160. In an embodiment, the antenna1160comprises an FDD/TDD antenna.

In an embodiment, the switching circuit1190comprises the switching module1000including the semiconductor die1002. In another embodiment, switching circuit1190comprises the switching module1010including the filtering semiconductor die1012and the switching semiconductor die1014. In a further embodiment, the switching circuit1190comprises the multi-chip module1020including one or more SAW or BAW filters1022and the switching semiconductor die1014. In such embodiments, the switching circuit1190can comprises one or more of the switching circuits500,700,800ofFIGS.5,7, and8, respectively.

A signal received by antenna1160will be directed from the front-end module1162to the receiver1170. The receiver1170includes low noise amplifier circuitry1172, a downconverter1174, a filter1176, and a demodulator1178.

If implemented using a direct conversion receiver (DCR), the downconverter1174converts the amplified received signal from an RF level to a baseband level (DC), or a near-baseband level (approximately 100 kHz). Alternatively, the amplified received RF signal may be downconverted to an intermediate frequency (IF) signal, depending on the application. The downconverted signal is sent to the filter1176. The filter1176comprises a least one filter stage to filter the received downconverted signal as known in the art.

The filtered signal is sent from the filter1176to the demodulator1178. The demodulator1178recovers the transmitted analog information and supplies a signal representing this information via connection1186to the ADC1134. The ADC1134converts these analog signals to a digital signal at baseband frequency and transfers the signal via bus1128to the DSP1126for further processing.

It is to be appreciated that embodiments of the methods and apparatuses discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The methods and apparatuses are capable of implementation in other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting.

Throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The words “coupled” or “connected”, as generally used herein, refer to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

The above detailed description of certain embodiments is not intended to be exhaustive or to limit the invention to the precise form disclosed above. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those ordinary skilled in the relevant art will recognize in view of the disclosure herein.

For example, while processes or blocks are presented in a given order, alternative embodiments may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these processes or blocks may be implemented in a variety of different ways. In addition, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to other systems, not necessarily the systems described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments.