System and method for a low noise amplifier

An embodiment described herein includes a low noise amplifier (LNA) including a plurality of separate input terminals, a plurality of transistors, and an output network coupled to a first reference terminal and a single output of the LNA. Each transistor includes a conduction path and a control terminal coupled to one of the plurality of separate input terminals. The output network is also coupled to the conduction path of each of the plurality of transistors.

TECHNICAL FIELD

The present invention relates generally to circuits and amplifiers, and, in particular embodiments, to a system and method for a low noise amplifier (LNA).

BACKGROUND

Electronic devices used with wireless communication systems, such as cellular phones, GPS receivers, and Wi-Fi enabled notebook and tablet computers, generally contain signal processing systems that have interfaces to the analog world. Such interfaces may include wire line and wireless receivers that receive transmitted power and convert the received power to an analog or digital signal that may be demodulated using analog or digital signal processing techniques. A typical wireless receiver architecture includes a low noise amplifier (LNA) that amplifies the very small signals that may be received by an antenna, provides gain to these small signals and passes an amplified signal to later amplification and/or signal processing stages. By providing gain at the LNA, subsequent gain processing stages are made insensitive to noise, thereby enabling a lower system noise figure.

An LNA circuit generally contains at least one transistor and an input matching network. The purpose of the input matching network, which may be made of one or more passive devices such as inductors and capacitors, is to provide an impedance match and/or a noise match to a previous stage, such as an antenna, a filter, an RF switch, or other circuit. LNA implementations may also include an output matching network, a bias network, and other circuit structures such as a cascode transistor.

As wireless RF devices are being used in more environments with more varied specifications, the signal path from antenna system to processing circuit is of increasing importance. Particularly, the placement and usage of LNAs in such varied and demanding systems present varied challenges. Among other things, challenging aspects of designing modern wireless RF devices may include reducing the effects of attenuation, decreasing sensitivity to noise, reducing cost, reducing design time and challenge, and increasing system data rates. These challenges, which often are conflicting or mutually exclusive, present opportunities for improved LNA circuits and system configurations.

SUMMARY OF THE INVENTION

In accordance with an embodiment, a low noise amplifier (LNA) includes a plurality of separate input terminals, a plurality of transistors, and an output network coupled to a first reference terminal and a single output of the LNA. Each transistor includes a conduction path and a control terminal coupled to one of the plurality of separate input terminals. The output network is also coupled to the conduction path of each of the plurality of transistors.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of various embodiments are discussed in detail below. It should be appreciated, however, that the various embodiments described herein are applicable in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use various embodiments, and should not be construed in a limited scope.

Description is made with respect to various embodiments in a specific context, namely wireless systems, and more particularly, low noise amplifiers (LNAs) in antenna systems. Some of the various embodiments described herein include antenna systems for mobile communications, multiband communications systems, amplifier circuits, LNA circuits, LNA circuits with matching networks and degeneration elements, and LNAs placed near antenna systems and distant from processing circuits. In other embodiments, aspects may also be applied to other applications involving any type of communication system or amplifier according to any fashion as known in the art.

According to embodiments described herein, an LNA bank including multiple LNAs coupled to a filter bank is disclosed. The filter bank is coupled to an antenna switch and the antenna switch to an antenna system. The antenna switch, filter bank, and LNA bank are cascaded in close proximity to each other in order to reduce attenuation between the circuits. The LNA bank is coupled to an RF chipset via a single coaxial cable and the RF chipset may be disposed more distant from the LNA bank than the LNA bank is from the other components. In some embodiments, the LNAs in the LNA bank may only have a single LNA enabled or selected at a given time. In other embodiments, multiple LNAs in the LNA bank may be enabled of selected simultaneously. In such embodiments, the LNA bank includes a matching network.

FIG. 1illustrates a block diagram of a conventional wireless system100including antenna system102, diplexer104, antenna switch106, filter bank108, LNA bank110, and RF chipset112. According to the conventional art, antenna system102receives signals in different frequency bands, such as low band (LB), mid band (MB), or high band (HB), and multiplexes the signals at diplexer104before conveying the signals to antenna switch106through coaxial cable114. Antenna switch106selects a switch coupling to supply a specific filter1-nin filter bank108. The specific filter1-nfilters and selects a specific frequency band and supplies the filtered signals to an LNA1-nin LNA bank110. The specific LNA1-nsupplies amplified signals to RF chipset112where more processing may be performed.

As described in brief in the background, attenuation and noise are relevant in electronic systems such as wireless system100. Increasing the physical distance between each of components102-112may increase the attenuation between each stage, thereby degrading the noise performance of the system. Particularly, the coaxial cable114coupled between antenna system102and antenna switch104may cause significant attenuation.

Thus, embodiments described herein include a wireless system with an antenna switch, filter bank, and LNA bank placed in close proximity and configured to be less affected by attenuation and less sensitive to noise. Embodiment wireless systems may include an antenna system with multiple antennas arranged in order to increase signal reception. These antennas may be placed more distant from the RF chipset and may be coupled through a coaxial cable. According to various embodiments, amplification is performed in an LNA bank in close proximity to the antenna switch and prior to the coaxial cable in the signal path of the cascaded circuit. Thus, amplification is performed before more significant attenuation occurs and the overall noise figure is reduced.

FIG. 2illustrates a block diagram of an embodiment wireless system120which illustrates the above mentioned aspects and includes antenna system122, antenna switch124, filter bank126, LNA bank128, and RF chipset132. According to various embodiments, antenna switch124, filter bank126, and LNA bank128are placed in close proximity on package134and antenna system122may also be placed in close proximity or more distant. In some embodiments, antenna switch124, filter bank126, and LNA bank128placed immediately adjacent to one another. In various embodiments, RF chipset132is placed further from LNA bank128and coupled to LNA bank128via coaxial cable130. In specific embodiments, antenna system122may include a diplexer and an antenna configured to transmit or receive low band (LB) and mid band (MB) signals. In some embodiments, antenna system122may include a separate high band (HB) antenna or a separate low band (LB) antenna. Antenna system122may also include a combined mid band and high band MB/HB antenna without a diplexer.

According to various embodiments, signals are received at antenna system122. These signals may include multiple frequency bands. For example, the signals may include a low band (LB) of 700-900 MHz, a mid band (MB) of 1.8-2.4 GHz, and a high band (HB) of 2.5-3.5 GHz. Other embodiments may include more or fewer bands, as is explained further below, and the bands may range across different frequency ranges. Antenna switch124is controlled to select specific switch configurations and couple the signals to specific filters of filters1-nin filter bank126. LNA bank128receives the filtered signals with selected frequency bands from the specific filters in filter bank126at corresponding LNAs of LNAs1-min LNA bank128. Further, the received signals are multiplexed at LNA bank128and provided on a single output to RF chipset132via coaxial cable130.

Depending on the system requirements or usage environment, various embodiments include numerous variations. For example, antenna system122may include multiple antennas. In other embodiments, antenna system122includes a single antenna. Antenna system122may include a single tunable antenna or multiple tunable antennas, where each tunable antenna is controlled to transmit and receive specific frequency bands. Antenna switch124may include any number of switches. Antenna switch124is shown as including two single pole n throw switches, but any configuration is possible. Filter bank126includes n filters of any type, such as passive or active filters for any type of band filtering (low pass, band pass, or high pass). In different embodiments, n may range from 1 to any number.

In various embodiments, LNA bank128includes m LNAs coupled to filters1-nin filter bank126and to coaxial cable130. The number m of LNAs in LNA bank128may be the same as the number n of filters in filter bank126or may be a different number. An LNA in LNA bank128may receive inputs from a single filter or multiple filters together. The outputs of LNAs1-min LNA bank128are multiplexed at the single output and coupled to coaxial cable130in order to be conveyed to RF chipset132. In various embodiments, multiple LNA banks may be combined and multiple coaxial connections may be coupled between RF chipset132and the various LNA banks. In such embodiments, each LNA bank includes multiple LNAs multiplexed at a single output. In some embodiments, only a single LNA in LNA bank128may be enabled or selected at any given time. In other embodiments, multiple LNAs may be selected or enabled at a given time and the signals may be multiplexed at the output. Generally, different types of embodiment LNAs are used for multiplexing than for other embodiments, as is described further below in reference to the other figures.

Additional components may be included in wireless system120that are not shown, such as additional communication systems, diplexers, multiplexers, standalone filters, and processing circuits. According to various embodiments, wireless system120is formed on package134, which may be any type of system. For example, package134may be printed circuit board (PCB) in a mobile device, such as a cell phone or tablet computer.

The placement of components including antenna system122, antenna switch124, filter bank126, or LNA bank128close together includes various configurations in different embodiments. In some embodiments, the components are placed immediately adjacent to one another, or antenna system122may be more distant and antenna switch124, filter bank126, and LNA bank128are paced immediately adjacent to one another. Specifically, antenna switch124, filter bank126, and LNA bank128may be placed less than 1 mm apart on package134while RF chipset132may be placed more than 70 mm away from LNA bank128. Alternatively, the ratio of distances may be relevant such that the ratio of the distances between LNA bank128, filter bank126, and antenna switch124to the distance between LNA bank128and RF chipset132is less than 1:2. In more particular embodiments, the ratio is less than or equal to 1:10. That is to say, RF chipset132is ten times or more further from LNA bank128than filter bank126is from either LNA bank128or antenna switch124. In other embodiments, the components including antenna switch124, filter bank126, or LNA bank128are placed such that less than 10% of the major dimension of wireless system120is between two components. For example, wireless system120may be a mobile phone with a long side of 5 inches (12.7 cm), the components are placed such that less than 0.5 inches (1.27 cm) is between two components. In some embodiments, antenna system122may also be placed immediately adjacent to antenna switch124, such as less than 10% of the major dimension of wireless system120or with a ratio less than 1:2 compared to the distance between LNA bank128and RF chipset132.

Various LNAs will be described in reference toFIGS. 3-8.

FIG. 3illustrates a schematic of a conventional low noise amplifier (LNA)140including amplifying element142, degeneration element144, and output tank146. Amplifying element142is connected to an LNA input148and provides a current path to output tank146that provides output150. As shown, amplifying element142is a bipolar junction transistor (BJT), output tank includes an inductor and two capacitors, and degeneration element144is an inductor.

FIG. 4illustrates a block diagram of an embodiment low noise amplifier (LNA) system160including amplifiers162,164, and166, degeneration element168, matching network170, and bias circuit178. According to various embodiments, LNA system160operates as three LNAs with three separate inputs172,174, and176. Each of inputs172,174, and176receives a signal from an antenna or filter as discussed in reference to the other figures. The signals are amplified by amplifiers162,164, and166and provided as output signals through matching network170at output175. Matching network170may provide impedance matching on output175; degeneration element168may increase the linearity of and adjust the gain of amplifiers162,164, or166; and bias circuit178selects or enables amplifiers162,164, or166. In some embodiments, matching network170may include multiple blocks coupled to amplifiers162,164, or166for impedance matching in specific frequency bands. Likewise, degeneration element168may include multiple degeneration elements coupled to amplifiers162,164, and166, such as inductors for example. In some embodiments, bias circuit178may select or enable only a single amplifier162,164, or166at a given time. In other embodiments, bias circuit178may select or enable multiple amplifiers at a given time. Specific embodiments are explained in reference toFIGS. 5-8.

FIGS. 5aand 5billustrate schematics of embodiment low noise amplifier (LNA) systems180and181, each including an output tank, n amplifiers, and a degeneration element. According to various embodiments, LNA system180illustrated inFIG. 5aincludes bipolar junction transistors (BJTs)1-ncontrolled at a control terminal by inputs182a-182n, which may be coupled to an antenna system or filter bank as described in reference to the other figures. In LNA system180, the conduction path of each BJT1-nis coupled to an individual degeneration element184a-184n, respectively, that is also coupled to a reference terminal, such as ground. Each degeneration element184a-184nmay be an inductor, for example, or may include other components. Each BJT1-nis also coupled to an output tank that is coupled to a supply terminal, such as VCC, and includes inductor186and capacitors187and188with output190coupled between capacitors186and187. In various embodiments, the output tank may be implemented in other types of configurations with any number of inductors, capacitors, or resistors. In some embodiments, the output tank is not an LC tank, but may include another type of output network that is inductive, resistive, capacitive, or some combination thereof. In an embodiment, LNA system180may only have one of transistors1-nselected or enabled at a time, which may be controlled by a biasing circuit coupled to input182a-182n, such as bias circuit178.

According to various embodiments, LNA system181illustrated inFIG. 5bincludes BJTs1-ncoupled to inputs192a-192n, an output tank including inductor196and capacitors197and198coupled to output191, and a single degeneration element194that is coupled to the conduction path of each BJT1-n. The description of LNA system180above also applies to LNA system181with the exception that degeneration element194is a single element coupled to each BJT1-n.

FIG. 6illustrates a schematic of another embodiment low noise amplifier (LNA) system200including matching networks202,204, and206coupled through amplification elements to input terminals210a-210nand to output terminal208. According to various embodiments, the amplification elements are BJTs1-nthat include conduction paths from matching networks202,204, or206through a degeneration element212a-212nto a reference terminal, such as ground, as shown. In various embodiments, the number of transistors1-nmay include any number.

According to various embodiments, each matching network202,204, and206includes a configuration of capacitors and inductors in order to perform impedance matching for a specific frequency band. Matching network202is configured to have a low pass (LP) impedance Zin_LP that is a low impedance matched to the impedance coupled to output terminal208for low frequencies. For example, the low band (LB) may include frequencies ranging from 700 to 900 MHz. Similarly, matching network204may include inductors and capacitors configured to have a band pass (BP) impedance Zin_BP that is a low impedance matched to the impedance coupled to output terminal208for mid band (MB) frequencies. For example, the mid band (MB) may include frequencies ranging from 1.8 to 2.4 GHz. Further, matching network206may include inductors and capacitors configured to have a high pass (HP) impedance Zin_HP that is a low impedance matched to the impedance coupled to output terminal208for high frequencies. For example, the high band (HB) may include frequencies ranging from 2.5 to 3.5 GHz. In other embodiments, the LB, MB, and HB may include larger or smaller frequency bands. For example, HB may include frequencies ranging above 3.5 GHz.

In the embodiments shown, matching network202includes two inductors and a capacitor configured as a low pass filter; matching network204includes two inductors and two capacitors configured as a band pass filter; and matching network206includes one inductor and two capacitors configured as a high pass filter. When each matching network202,204, or206is within the respective frequency band LB, MB, or HB, the corresponding impedance Zin_LP, Zin_BP, or Zin_HP is low and matched to an output line coupled to output terminal208. In cases where each matching network202,204, or206is outside the respective frequency band LB, MB, or HB (i.e., out of band), the corresponding impedance Zin_LP, Zin_BP, or Zin_HP is high or near an open circuit. Due to this configuration of LNAs, multiple LNAs coupled to output terminal208can be operating simultaneously and multiple signals may be multiplexed and conveyed on a single coupling connected to output terminal208, such as a coaxial cable, for example.

In the various embodiments, each matching network202,204, or206may include multiple inputs and multiple transistors coupled to a single matching network as shown, for example, with inputs210c-210ncoupled to control terminals of transistors3-n, which include conduction paths from matching network206to reference terminals through degeneration elements212c-212n. In such embodiments, the transistors may be implemented by coupling transistors in parallel. In some embodiments, only a single transistor coupled to each matching network may be enabled or selected at a time. Any configuration as explained, for example, in reference toFIGS. 5aand 5bin terms of transistor and degeneration element coupling may be applied to LNA system200. Degeneration elements212a-212nmay include only single inductors as shown. In other embodiments, degeneration elements212a-212nmay include any other combination of circuit elements.

FIG. 7illustrates a schematic of further embodiment low noise amplifier (LNA) system201including higher order filters in matching networks222,224, and226. The description of LNA system201is similar to the description of LNA system200above in reference toFIG. 6. Similar components function in a similar manner.

According to various embodiments, LNA system201includes BJTs1-nwith control terminals coupled to inputs230a-230nand conduction paths from matching network222,224, or226to a reference terminal via degeneration elements232a-232n. Matching networks222,224, and226include higher order filters than matching networks202,204, and206inFIG. 6. In various embodiments, matching network222includes a low pass filter with three inductors and two capacitors, matching network224includes a band pass filter with four inductors and four capacitors, and matching network226includes a high pass filter with two inductors and three capacitors, as illustrated. The higher order of matching networks222,224, and226may allow the frequency bands LB, MB, or HB to be more clearly defined by increasing the slope of the gain roll-off outside the respective frequency bands. Other embodiments may include any type of matching network configuration with any number of circuit components.

FIG. 8illustrates a more detailed schematic of a low noise amplifier (LNA) system240including bias circuit242, degeneration element244, output tank246, and BJT Q1awith a control terminal coupled to input252. According to various embodiments, output tank246, which may be an implementation of a matching network as described herein, includes inductor L1and capacitor C4coupled to output250; degeneration element244includes inductor L2coupled to a reference such as ground; and bias circuit242includes capacitors C1-C3, BJT Q2, and resistors R1-R4. Bias circuit242is supplied by a reference current Irefon input251. In various embodiments, additional LNAs are coupled to output250in LNA system240as illustrated by LNA248, which includes input253coupled to bias circuit243and BJT Q1b, as well as degeneration inductor L3. Other configurations of transistors, output tanks, bias circuits, and degeneration elements are envisioned, as described herein in reference to the other figures.

Generally, in all the figures presented herein, the amplifying elements and/or transistors may be implemented as any type of transistor. For example, transistors described herein may include complementary metal oxide semiconductor (CMOS) transistors, BJTs, gallium arsenide transistors, FinFETs, or any other implementation as is known in the art.

FIG. 9illustrates a more detailed block diagram of another embodiment wireless system300including antenna switch306, filters B1-B10, LNA bank308, LNA bank310, and select switch318. According to various embodiments, inputs are received from an antenna or group of antennas at input302. The signals received at input302are conveyed to antenna switch306. Antenna switch306selects filters B1-B10, which include frequency bands B1-B10. Selected signals from antenna switch306are supplied to filters B1-B10that filter the signals and supply bands B1-B10to LNAs1-8in LNA bank308and LNA bank310via inductors L11-L18. Outputs of LNA banks308and310are coupled to select switch318that selects one of the signal paths to provide as output RFOUT.

According to various embodiments, LNA banks308and310include a reduced number of outputs by including LNAs with outputs coupled together and diplexed or multiplexed, as described in reference to the other figures included herein. For example, LNA1and LNA3have diplexed outputs coupled to terminal RX4on switch318, LNA2and LNA3have diplexed outputs coupled to terminal RX3on switch318, LNA5and LNA7have diplexed outputs coupled to terminal RX2on switch318, and LNA6and LNA8have diplexed outputs coupled to terminal RX1on switch318. Outputs of each LNA may also be multiplexed or diplexed using additional components such as a low pass filter or band pass filter. In some embodiments, an LNA bank only has a single common output coupled to the outputs of every LNA in the LNA bank (not shown), as described herein in reference to the other figures.

In various embodiments, band filters B1-B10may include any frequency band such as low band, mid band, and high band frequencies. In some embodiments, band filters may include frequency bands with frequencies ranging from 100 MHz to 10 GHz with bands as narrow as a 0.01 MHz or as wide as 200 MHz. Other frequency bands may be included in alternative embodiments. In one embodiment, LNA bank308is coupled to low band signals and LNA bank310is coupled to high band signals.

In some embodiments, wireless system300is disposed on a single circuit board320. The circuit board320may be part of a mobile phone or other mobile device. In an embodiment, blocks308and310are each formed on a separate semiconductor die or circuit board before being packaged in wireless system300.

FIG. 10illustrates a block diagram of an embodiment method of operating a wireless system400, including steps402-410, in order to convey a plurality of signals in a plurality of frequency bands. According to various embodiments, step402includes receiving a first signal at an input of a first LNA and step404includes receiving a second signal at an input of a second LNA. In step406, the first signal is amplified at the first LNA and the second signal is amplified at the second LNA. The first and second signals are multiplexed at a shared output of the first and second LNAs in step408. Step410includes supplying the first and second signals to a processing circuit on a single coupling line coupled to the shared output. In various embodiments, method of operation400may include additional steps and steps402-410may be performed in various different orders.

FIG. 11illustrates a block diagram of an alternative embodiment wireless system340including antenna system342, antenna switch344, filter bank346, LNA bank348including LNAs1-n, and RF chipset350. In such alternative embodiments, each LNA1-nincludes a separate coupling to RF chipset350. Wireless system340may be included on circuit board352.

According to various embodiments, a low noise amplifier (LNA) includes a plurality of separate input terminals, a plurality of transistors, and an output network coupled to a first reference terminal and a single output of the LNA. Each transistor includes a conduction path and a control terminal coupled to one of the plurality of separate input terminals. The output network is also coupled to the conduction path of each of the plurality of transistors.

In various embodiments, the LNA includes a plurality of degeneration elements and each degeneration element is coupled between the conduction path of a transistor of the plurality of transistors and a second reference terminal. The LNA may also include a degeneration element coupled between the conduction path of each transistor of the plurality of transistors and a second reference terminal. In some embodiments, the degeneration element is an inductor.

In various embodiments, the output network includes an LC tank. In some embodiments, the output network includes a complex impedance substantially matched to an impedance coupled to the single output of the LNA. The output network may have a first impedance in-band and a second impedance out of band. The second impedance is greater than the first impedance. In one embodiment, the first impedance is substantially matched to an impedance coupled to the single output of the LNA. In various embodiments, the LNA also includes a bias network coupled to the control terminal of each of the plurality of transistors. The bias network is configured to activate one transistor of the plurality of transistors at a time.

According to various embodiments, a low noise amplifier (LNA) bank includes a first LNA and a second LNA. The first LNA includes a first transistor including a control terminal coupled to a first input of the LNA bank and a first output network coupled to a conduction path of the first transistor and an output of the LNA bank. The first output network is configured to have a first type of output impedance in a first frequency band and a second type of output impedance outside the first frequency band. The second LNA includes a second transistor including a control terminal coupled to a second input of the LNA bank and a second output network coupled to a conduction path of the second transistor and the output of the LNA bank. The second output network is configured to have the first type of output impedance in a second frequency band and the second type of output impedance outside the second frequency band.

In various embodiments, the first output network includes a first LC tank and the second output network includes a second LC tank. The LNA bank may also include a third LNA including a third transistor including a control terminal coupled to a third input of the LNA bank and a third output network coupled to a conduction path of the third transistor and the output of the LNA bank. The third output network is configured to have the first type of output impedance in a third frequency band and the second type of output impedance outside the third frequency band. In some embodiments, the first frequency band is a low band, the second frequency band is a mid band, and the third frequency band is a high band. The LNA bank may also include a first degeneration element coupled to the conduction path of the first transistor, a second degeneration element coupled to the conduction path of the second transistor, and a third degeneration element coupled to the conduction path of the third transistor. The first, second, and third degeneration elements may each include an inductor.

In various embodiments, the first or second transistors include a plurality of transistors, each transistor including control terminals coupled to a plurality of separate inputs of the LNA bank and conduction paths coupled to the respective first or second output networks. In some embodiments, the first type of output impedance is substantially matched to an impedance coupled to the output of the LNA bank in respective frequency bands and the second type of output impedance is higher than the first type of output impedance in respective frequency bands. In particular embodiments, the first type of output impedance is 50Ω in respective frequency bands and the second type of output impedance is higher than 200Ω in respective frequency bands.

According to various embodiments, a method includes receiving a first signal at an input of a first low noise amplifier (LNA), receiving a second signal at an input of a second LNA, amplifying the first signal at the first LNA and amplifying the second signal at the second LNA, multiplexing the first and second signals at a shared output line of the first LNA and the second LNA, and supplying the first and second signals to a processing circuit on a single coupling line coupled to the shared output.

In various embodiments, the first LNA, the second LNA, and the shared output line are formed on a single semiconductor die. Receiving the first signal and receiving the second signal may be performed simultaneously and the first and second signals may be supplied to the processing circuit simultaneously. In some embodiments, receiving the first and second signals includes receiving first and second signals from a filter bank that is coupled to an antenna circuit. The filter bank, the first LNA, and the second LNA may be disposed in proximity to one another on a same chip in proportion to a size of the chip. In some specific embodiments, disposed in proximity includes disposed immediately adjacent on a same chip. In other embodiments, disposed in proximity includes disposed within 10% of a longest dimension of the chip. Further, the single coupling line may be a coaxial cable and the processing circuit may be disposed on the same chip distant from the antenna circuit, the filter bank, the first LNA, and the second LNA.

According to various embodiments, a wireless system includes an antenna system, a filter bank coupled to the antenna system, and a low noise amplifier (LNA) bank coupled to the filter bank. The filter bank includes a plurality of filters and each filter in the plurality of filters is coupled to the antenna system. The LNA bank includes a plurality of LNAs coupled to the plurality of filters and to a single output of the LNA bank. The single output of the LNA bank is configured to be coupled to a processing circuit located electrically distant the LNA bank. The antenna system is located within a first distance from the filter bank, the LNA bank is located within the first distance from the filter bank, and the LNA bank is configured to be located within a second distance from the processing circuit.

In various embodiments, the second distance is greater than or equal to 5 times the first distance. The wireless system may also include an antenna switch coupled between the antenna system and the filter bank. The antenna switch includes a plurality of switch outputs and each switch output of the plurality of switch outputs is coupled to a filter in the plurality of filters. In some embodiments, the wireless system includes a mobile communication device disposed on a single circuit board. In such an embodiment, the antenna switch is disposed immediately adjacent to the filter bank and the filter bank is disposed immediately adjacent to the LNA bank. Some embodiments include the processing circuit. The single output of the LNA bank may be coupled to the processing circuit through a coaxial cable.

In various embodiments, the LNA bank also includes a biasing circuit coupled between the plurality of filters and the plurality of LNAs. The biasing circuit is configured to enable a single LNA of the plurality of LNAs at a time. The LNA bank may also include a matching network coupled between the plurality of LNAs and the single output of the LNA bank. The matching network includes a plurality of LC tanks coupled to the plurality of LNAs and each LC tank of the plurality of LC tanks is configured to match an output impedance seen on the single output of the LNA bank in a specific frequency band.

According to various embodiments, a wireless system includes an antenna system, a low noise amplifier (LNA) bank coupled to the antenna system, and a processing circuit coupled to the single output of the LNA bank via a coaxial cable. The LNA bank includes a plurality of LNAs coupled to a single output of the LNA bank and formed on a single semiconductor die. The LNA bank is located within a first distance of the antenna system and the processing circuit is located outside a second distance that is at least 10 times greater than the first distance. In various embodiments, the first distance is 1 mm and the second distance is 70 mm.

According to embodiments of the invention, advantages may include low attenuation between signal sources and processing circuits due to improved LNA placement near the signal source. Other advantages may include reduced routing effort for printed circuit board (PCB) layout and design due to diplexing and multiplexing of outputs for LNAs. In some embodiments, a smaller PCB may be used due to the reduced routing effort. Further advantages include a reduced noise figure and higher sensitivity in some embodiments.