Patent Publication Number: US-2021184346-A1

Title: Radio frequency systems with tunable filter

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet, or any correction thereto, are hereby incorporated by reference under 37 CFR 1.57. 
     BACKGROUND 
     Field 
     Embodiments of the invention relate to electronic systems, and in particular, to radio frequency (RF) electronics. 
     Description of Related Technology 
     RF systems can be used for transmitting and/or receiving signals of a wide range of frequencies. For example, an RF system can be used to wirelessly transmit and receive RF signals in a frequency range of about 30 kilohertz (kHz) to 300 gigahertz (GHz), such as in the range of about 450 megahertz (MHz) to about 7 GHz for certain communications standards. 
     Examples of RF systems include, but are not limited to, mobile phones, tablets, base stations, network access points, customer-premises equipment (CPE), laptops, and wearable electronics. 
     SUMMARY 
     In certain embodiments, the present disclosure relates to a mobile device. The mobile device includes a first antenna and a front end circuit electrically coupled to the first antenna. The front end circuit includes a first radio frequency processing circuit implemented to support reception of a first frequency band of a first communication standard and a second frequency band of a second communication standard, the first radio frequency processing circuit including a tunable filter having adjustable bandwidth to control an amount of filtering provided to a blocker signal of a third frequency band. The front end circuit further includes a second radio frequency processing circuit configured to generate a transmit signal in the third frequency band. 
     In some embodiments, the mobile device further includes a second antenna configured to receive the transmit signal from the second radio frequency processing circuit, and the blocker signal arises from antenna-to-antenna coupling between the first antenna and the second antenna. 
     In a number of embodiments, the front end circuit further includes a diplexer configured to couple the first radio frequency processing circuit and the second radio frequency processing circuit to the first antenna, and the blocker signal arises from a finite isolation of the diplexer. 
     In some embodiments, the tunable filter operates with a first bandwidth in a first mode and with a second bandwidth in a second mode, the first mode providing a higher amount of filtering to the blocker signal than the second mode. According to several embodiments, first bandwidth is narrower than the second bandwidth. In accordance with various embodiments, the tunable filter has higher insertion loss in the first mode relative to the second mode. According to a number of embodiments, selection between the first mode and the second mode is controlled based on data received over a serial interface. In accordance with several embodiments, the front end circuit further includes a blocker detector configured to generate a detection signal based on detecting for the blocker signal, and the selection between the first mode and the second mode is controlled based on the detection signal. According to various embodiments, the detector is implemented along a radio frequency signal path through the first radio frequency processing circuit. In accordance with a number of embodiments, the detector is implemented along a radio frequency signal path through the second radio frequency processing circuit. According to several embodiments, the tunable filter includes a notch filter component that is activated in the first mode and deactivated in the second mode. In accordance with various embodiments, selection between the first mode and the second mode is controlled based on whether the second radio frequency processing circuit is transmitting the transmit signal. 
     In a number of embodiments, the third frequency band is of the second communication standard. 
     In several embodiments, the first communication standard is long term evolution (LTE) and the second communication standard is fifth generation (5G). 
     In various embodiments, the first frequency band is LTE B42, the second frequency band is 5G n77, and the third frequency band is 5G n79. 
     In certain embodiments, the present disclosure relates to a front end system. The front end system includes a first radio frequency processing circuit implemented to support reception of a first frequency band of a first communication standard and a second frequency band of a second communication standard. The first radio frequency processing circuit includes a tunable filter having adjustable bandwidth to control an amount of filtering provided to a blocker signal of a third frequency band. The front end system further includes a second radio frequency processing circuit configured to generate a transmit signal in the third frequency band. 
     In a number of embodiments, the tunable filter operates with a first bandwidth in a first mode and with a second bandwidth in a second mode, the first mode providing a higher amount of filtering to the blocker signal than the second mode. 
     In certain embodiments, the present disclosure relates to a method of radio frequency communication. The method includes receiving a first signal and a second signal via an antenna, the first signal of a first frequency band of a first communication standard and the second signal of a second frequency band of a second communication standard. The method further includes processing the first signal and the second signal using a first radio frequency processing circuit, transmitting a transmit signal in a third frequency band using a second radio frequency processing circuit, and controlling an amount of filtering provided to a blocker signal of the third frequency band by adjusting a bandwidth of a tunable filter of the first radio frequency processing circuit. 
     In several embodiments, controlling the amount of filtering includes operating the tunable filter with a first bandwidth in a first mode and with a second bandwidth in a second mode, the first mode providing a greater amount of filtering to the blocker signal than the second mode. 
     In a number of embodiments, the first bandwidth is narrower than the second bandwidth. 
     In certain embodiments, the present disclosure relates to a mobile device including a first antenna and a front end circuit electrically coupled to the first antenna and including a first radio frequency processing circuit implemented to support reception of a first frequency band of a first communication standard and a second frequency band of a second communication standard. The first radio frequency processing circuit including a tunable filter having adjustable bandwidth to control an amount of filtering provided to a blocker signal of a third frequency band. 
     In some embodiments, the front end circuit further includes a second radio frequency processing circuit configured to generate a transmit signal in the third frequency band. According to several embodiments, the mobile device further includes a second antenna configured to receive the transmit signal from the second radio frequency processing circuit, the blocker signal arising from antenna-to-antenna coupling between the first antenna and the second antenna. In accordance with various embodiments, the front end circuit further includes a diplexer configured to couple the first and second radio frequency processing circuits to the first antenna, the blocker signal arising from a finite isolation of the diplexer. According to a number of embodiments, the first radio frequency processing circuit is implemented on a first radio frequency module and the second radio frequency processing circuit is implemented on a second radio frequency module. 
     In several embodiments, the tunable filter operates with a first bandwidth in a first mode and with a second bandwidth in a second mode, the first mode providing a higher amount of filtering to the blocker signal than the second mode. According to a number of embodiments, the first bandwidth is narrower than the second bandwidth. In accordance with various embodiments, the tunable filter has higher insertion loss in the first mode relative to the second mode. According to some embodiments, selection between the first mode and the second mode is controlled based on data received over a serial interface. In accordance with a number of embodiments, the mobile device further includes a system-level control circuit configured to control selection between the first mode and the second mode. According to various embodiments, the system-level control circuit is a transceiver or a baseband processor. In accordance with some embodiments, the front end circuit further includes a blocker detector configured to generate a detection signal based on detecting for the blocker signal, the selection between the first mode and the second mode controlled based on the detection signal. According to a number of embodiments, the detector is implemented along a radio frequency signal path through the first radio frequency processing circuit. In accordance with various embodiments, the front end circuit further includes a second radio frequency processing circuit, the detector implemented along a radio frequency signal path through the second radio frequency processing circuit. According to a number of embodiments, the tunable filter includes a notch filter component that is activated in the first mode and deactivated in the second mode. In accordance with various embodiments, the front end circuit further includes a second radio frequency processing circuit configured to generate a transmit signal of the third frequency band, the selection between the first mode and the second mode controlled based on whether the second radio frequency processing circuit is transmitting the transmit signal. 
     In some embodiments, the third frequency band is of the second communication standard. 
     In a number of embodiments, the first communication standard is long term evolution (LTE) and the second communication standard is fifth generation (5G). 
     In several embodiments, the first communication standard is WiFi and the second communication standard is 5G. 
     In various embodiments, the first communication standard is WiFi and the second communication standard is LTE. 
     In some embodiments, the first frequency band is LTE B42 and the second frequency band is 5G n77. According to several embodiments, the third frequency band is 5G n79. 
     In a number of embodiments, the first frequency band and the second frequency band are partially overlapping in frequency. 
     In several embodiments, the tunable filter is configured to generate a filtered signal based on filtering a radio frequency input signal to the first radio frequency processing circuit. According to various embodiments, the first radio frequency processing circuit further includes a low noise amplifier configured to generate an amplified signal by amplifying the filtered signal, and a tunable output filter configured to filter the amplified signal. 
     In some embodiments, the mobile device further includes a transceiver electrically coupled to the front end circuit. 
     In certain embodiments, the present disclosure relates to a radio frequency module including a module substrate and a radio frequency processing circuit implemented on the module substrate. The radio frequency processing circuit is configured to receive a first radio frequency signal of a first frequency band, the radio frequency processing circuit including a tunable filter having adjustable bandwidth to control an amount of filtering provided to a blocker signal of a second frequency band. 
     In some embodiments, the first frequency band is LTE B42 and the second frequency band is 5G n79. According to several embodiments, the first frequency band is 5G n79 and the second frequency band is 5 gigahertz WiFi. In accordance with a number of embodiments, first frequency band is B40 and the second frequency band is 2 gigahertz WiFi. According to various embodiments, the first frequency band is B41 and the second frequency band is 2 gigahertz WiFi. In accordance with several embodiments, the first frequency band is B32 and the second frequency band is B11/B21. According to a number of embodiments, the first frequency band is of a first communication standard and the second frequency band is of a second communication standard. In accordance with various embodiments, the first communication standard is LTE and the second communication standard is 5G. According to several embodiments, the first communication standard is WiFi and the second communication standard is 5G. In accordance with a number of embodiments, the first communication standard is WiFi and the second communication standard is LTE. According to several embodiments, the radio frequency processing circuit is further configured to receive a second radio frequency signal of the second communication standard. In accordance with various embodiments, the first radio frequency signal is in LTE B42 and the second radio frequency signal is in 5G n77. According to a number of embodiments, the blocker signal is in 5G n79. 
     In some embodiments, the tunable filter operates with a first bandwidth in a first mode and with a second bandwidth in a second mode, the first mode providing a higher amount of filtering to the blocker signal than the second mode. According to several embodiments, the first bandwidth is narrower than the second bandwidth. In accordance with various embodiments, the tunable filter has higher insertion loss in the first mode relative to the second mode. According to a number of embodiments, the radio frequency module further includes a serial interface configured to receive data for controlling selection between the first mode and the second mode. In accordance with several embodiments, the radio frequency processing circuit includes a blocker detector configured to generate a detection signal based on detecting for the blocker signal, and the selection between the first mode and the second mode is controlled based on the detection signal. According to various embodiments, the tunable filter includes a notch filter component that is activated in the first mode and deactivated in the second mode. In accordance with a number of embodiments, the tunable filter is configured to generate a filtered signal based on filtering the first radio frequency signal. According to several embodiments, the radio frequency processing circuit further includes a low noise amplifier configured to generate an amplified signal by amplifying the filtered signal, and a tunable output filter configured to filter the amplified signal. In accordance with various embodiments, the radio frequency processing circuit is implemented at least in part on a semiconductor die that is attached to the module substrate. 
     In certain embodiments, the present disclosure relates to a method of radio frequency communication. The method includes receiving a first signal of a first frequency band of a first communication standard via an antenna, processing the first signal using a first radio frequency processing circuit, receiving a second signal of a second frequency band of a second communication standard via the antenna, processing the second signal using the first radio frequency processing circuit, and controlling an amount of filtering provided to a blocker signal of a third frequency band by adjusting a bandwidth of a tunable filter of the first radio frequency processing circuit. 
     In various embodiments, the method further includes transmitting a transmit signal in the third frequency band using a second radio frequency processing circuit. 
     In several embodiments, controlling the amount of filtering includes operating the tunable filter with a first bandwidth in a first mode and with a second bandwidth in a second mode, the first mode providing a greater amount of filtering to the blocker signal than the second mode. According to a number of embodiments, the first bandwidth is narrower than the second bandwidth. In accordance with some embodiments, the tunable filter has higher insertion loss in the first mode relative to the second mode. According to several embodiments, the method further includes receiving data over a serial interface, and controlling selection between the first mode and the second mode based on the data 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of this disclosure will now be described, by way of non-limiting example, with reference to the accompanying drawings. 
         FIG. 1  is a schematic diagram of one example of a communication network. 
         FIG. 2A  is a schematic diagram of one example of a downlink channel using multi-input and multi-output (MIMO) communications. 
         FIG. 2B  is schematic diagram of one example of an uplink channel using MIMO communications. 
         FIG. 3  is a schematic diagram of a radio frequency (RF) system including a front end circuit according to one embodiment. 
         FIG. 4A  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 4B  is a diagram showing one example of simulation results for the front end circuit of  FIG. 4A . 
         FIG. 4C  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 4D  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 4E  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 4F  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 4G  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 4H  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 5A  is a schematic diagram of one embodiment of an RF module. 
         FIG. 5B  is a schematic diagram of one embodiment of a notch filter circuit for a tunable filter. 
         FIG. 5C  is a diagram showing one example of simulation results for the RF module of  FIG. 5A . 
         FIG. 6A  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6B  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6C  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6D  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6E  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6F  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6G  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6H  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6I  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6J  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 6K  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7A  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7B  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7C  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7D  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7E  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7F  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7G  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7H  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7I  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 7J  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 8A  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 8B  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 8C  is a schematic diagram of another embodiment of a front end circuit. 
         FIG. 9  is a schematic diagram of another embodiment of an RF system. 
         FIG. 10  is a schematic diagram of another embodiment of an RF system. 
         FIG. 11  is a schematic diagram of one embodiment of a mobile device. 
         FIG. 12A  is a schematic diagram of one embodiment of a packaged module. 
         FIG. 12B  is a schematic diagram of a cross-section of the packaged module of  FIG. 12A  taken along the lines  12 B- 12 B. 
     
    
    
     DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS 
     The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in a multitude of different ways, for example, as defined and covered by the claims. In this description, reference is made to the drawings in which like reference numerals can indicate identical or functionally similar elements. It will be understood that elements illustrated in the figures are not necessarily drawn to scale. Moreover, it will be understood that certain embodiments can include more elements than illustrated in a drawing and/or a subset of the elements illustrated in a drawing. Further, some embodiments can incorporate any suitable combination of features from two or more drawings. 
     The International Telecommunication Union (ITU) is a specialized agency of the United Nations (UN) responsible for global issues concerning information and communication technologies, including the shared global use of radio spectrum. 
     The 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications standard bodies across the world, such as the Association of Radio Industries and Businesses (ARIB), the Telecommunications Technology Committee (TTC), the China Communications Standards Association (CCSA), the Alliance for Telecommunications Industry Solutions (ATIS), the Telecommunications Technology Association (TTA), the European Telecommunications Standards Institute (ETSI), and the Telecommunications Standards Development Society, India (TSDSI). 
     Working within the scope of the ITU, 3GPP develops and maintains technical specifications for a variety of mobile communication technologies, including, for example, second generation (2G) technology (for instance, Global System for Mobile Communications (GSM) and Enhanced Data Rates for GSM Evolution (EDGE)), third generation (3G) technology (for instance, Universal Mobile Telecommunications System (UMTS) and High Speed Packet Access (HSPA)), and fourth generation (4G) technology (for instance, Long Term Evolution (LTE) and LTE-Advanced). 
     The technical specifications controlled by 3GPP can be expanded and revised by specification releases, which can span multiple years and specify a breadth of new features and evolutions. 
     In one example, 3GPP introduced carrier aggregation (CA) for LTE in Release 10. Although initially introduced with two downlink carriers, 3GPP expanded carrier aggregation in Release 14 to include up to five downlink carriers and up to three uplink carriers. Other examples of new features and evolutions provided by 3GPP releases include, but are not limited to, License Assisted Access (LAA), enhanced LAA (eLAA), Narrowband Internet-of-Things (NB-IOT), Vehicle-to-Everything (V2X), and High Power User Equipment (HPUE). 
     3GPP introduced Phase 1 of fifth generation (5G) technology in Release 15, and plans to introduce Phase 2 of 5G technology in Release 16 (targeted for 2019). Subsequent 3GPP releases will further evolve and expand 5G technology. 5G technology is also referred to herein as 5G New Radio (NR). 
     5G NR supports or plans to support a variety of features, such as communications over millimeter wave spectrum, beam forming capability, high spectral efficiency waveforms, low latency communications, multiple radio numerology, and/or non-orthogonal multiple access (NOMA). Although such RF functionalities offer flexibility to networks and enhance user data rates, supporting such features can pose a number of technical challenges. 
     The teachings herein are applicable to a wide variety of RF systems, including, but not limited to, RF systems using advanced cellular technologies, such as LTE-Advanced, LTE-Advanced Pro, and/or 5G NR. 
       FIG. 1  is a schematic diagram of one example of a communication network  10 . The communication network  10  includes a macro cell base station  1 , a small cell base station  3 , and various examples of user equipment (UE), including a first mobile device  2   a,  a wireless-connected car  2   b,  a laptop  2   c,  a stationary wireless device  2   d,  a wireless-connected train  2   e,  and a second mobile device  2   f.    
     Although specific examples of base stations and user equipment are illustrated in  FIG. 1 , a communication network can include base stations and user equipment of a wide variety of types and/or numbers. 
     For instance, in the example shown, the communication network  10  includes the macro cell base station  1  and the small cell base station  3 . The small cell base station  3  can operate with relatively lower power, shorter range, and/or with fewer concurrent users relative to the macro cell base station  1 . The small cell base station  3  can also be referred to as a femtocell, a picocell, or a microcell. Although the communication network  10  is illustrated as including two base stations, the communication network  10  can be implemented to include more or fewer base stations and/or base stations of other types. 
     Although various examples of user equipment are shown, the teachings herein are applicable to a wide variety of user equipment, including, but not limited to, mobile phones, tablets, laptops, IoT devices, wearable electronics, customer premises equipment (CPE), wireless-connected vehicles, wireless relays, and/or a wide variety of other communication devices. Furthermore, user equipment includes not only currently available communication devices that operate in a cellular network, but also subsequently developed communication devices that will be readily implementable with the inventive systems, processes, methods, and devices as described and claimed herein. 
     The illustrated communication network  10  of  FIG. 1  supports communications using a variety of technologies, including, for example, 4G LTE, 5G NR, and wireless local area network (WLAN), such as WiFi. Although various examples of communication technologies have been provided, the communication network  10  can be adapted to support a wide variety of communication technologies. 
     Various communication links of the communication network  10  have been depicted in  FIG. 1 . The communication links can be duplexed in a wide variety of ways, including, for example, using frequency-division duplexing (FDD) and/or time-division duplexing (TDD). FDD is a type of radio frequency communications that uses different frequencies for transmitting and receiving signals. FDD can provide a number of advantages, such as high data rates and low latency. In contrast, TDD is a type of radio frequency communications that uses about the same frequency for transmitting and receiving signals, and in which transmit and receive communications are switched in time. TDD can provide a number of advantages, such as efficient use of spectrum and variable allocation of throughput between transmit and receive directions. 
     In certain implementations, user equipment can communication with a base station using one or more of 4G LTE, 5G NR, and WiFi technologies. In certain implementations, enhanced license assisted access (eLAA) is used to aggregate one or more licensed frequency carriers (for instance, licensed 4G LTE and/or 5G NR frequencies), with one or more unlicensed carriers (for instance, unlicensed WiFi frequencies). 
     The communication links can operate over a wide variety of frequencies. In certain implementations, communications are supported using 5G NR technology over one or more frequency bands that are less than 6 Gigahertz (GHz) and/or over one or more frequency bands that are greater than 6 GHz. In one embodiment, one or more of the mobile devices support a HPUE power class specification. 
     In certain implementations, a base station and/or user equipment communicates using beamforming. For example, beamforming can be used to focus signal strength to overcome path losses, such as high loss associated with communicating over high signal frequencies. In certain embodiments, user equipment, such as one or more mobile phones, communicate using beamforming on millimeter wave frequency bands in the range of 30 GHz to 300 GHz and/or upper centimeter wave frequencies in the range of 6 GHz to 30 GHz, or more particularly, 24 GHz to 30 GHz. 
     Different users of the communication network  10  can share available network resources, such as available frequency spectrum, in a wide variety of ways. 
     In one example, frequency division multiple access (FDMA) is used to divide a frequency band into multiple frequency carriers. Additionally, one or more carriers are allocated to a particular user. Examples of FDMA include, but are not limited to, single carrier FDMA (SC-FDMA) and orthogonal FDMA (OFDMA). OFDMA is a multicarrier technology that subdivides the available bandwidth into multiple mutually orthogonal narrowband subcarriers, which can be separately assigned to different users. 
     Other examples of shared access include, but are not limited to, time division multiple access (TDMA) in which a user is allocated particular time slots for using a frequency resource, code division multiple access (CDMA) in which a frequency resource is shared amongst different users by assigning each user a unique code, space-divisional multiple access (SDMA) in which beamforming is used to provide shared access by spatial division, and non-orthogonal multiple access (NOMA) in which the power domain is used for multiple access. For example, NOMA can be used to serve multiple users at the same frequency, time, and/or code, but with different power levels. 
     Enhanced mobile broadband (eMBB) refers to technology for growing system capacity of LTE networks. For example, eMBB can refer to communications with a peak data rate of at least 10 Gbps and a minimum of 100 Mbps for each user. Ultra-reliable low latency communications (uRLLC) refers to technology for communication with very low latency, for instance, less than 2 milliseconds. uRLLC can be used for mission-critical communications such as for autonomous driving and/or remote surgery applications. Massive machine-type communications (mMTC) refers to low cost and low data rate communications associated with wireless connections to everyday objects, such as those associated with Internet of Things (IoT) applications. 
     The communication network  10  of  FIG. 1  can be used to support a wide variety of advanced communication features, including, but not limited to, eMBB, uRLLC, and/or mMTC. 
       FIG. 2A  is a schematic diagram of one example of a downlink channel using multi-input and multi-output (MIMO) communications.  FIG. 2B  is schematic diagram of one example of an uplink channel using MIMO communications. 
     MIMO communications use multiple antennas for simultaneously communicating multiple data streams over common frequency spectrum. In certain implementations, the data streams operate with different reference signals to enhance data reception at the receiver. MIMO communications benefit from higher SNR, improved coding, and/or reduced signal interference due to spatial multiplexing differences of the radio environment. 
     MIMO order refers to a number of separate data streams sent or received. For instance, MIMO order for downlink communications can be described by a number of transmit antennas of a base station and a number of receive antennas for UE, such as a mobile device. For example, two-by-two (2×2) DL MIMO refers to MIMO downlink communications using two base station antennas and two UE antennas. Additionally, four-by-four (4×4) DL MIMO refers to MIMO downlink communications using four base station antennas and four UE antennas. 
     In the example shown in  FIG. 2A , downlink MIMO communications are provided by transmitting using M antennas  43   a,    43   b,    43   c,  . . .  43   m  of the base station  41  and receiving using N antennas  44   a,    44   b,    44   c,  . . .  44   n  of the mobile device  42 . Accordingly,  FIG. 2A  illustrates an example of M×N DL MIMO. 
     Likewise, MIMO order for uplink communications can be described by a number of transmit antennas of UE, such as a mobile device, and a number of receive antennas of a base station. For example, 2×2 UL MIMO refers to MIMO uplink communications using two UE antennas and two base station antennas. Additionally, 4×4 UL MIMO refers to MIMO uplink communications using four UE antennas and four base station antennas. 
     In the example shown in  FIG. 2B , uplink MIMO communications are provided by transmitting using N antennas  44   a,    44   b,    44   c,  . . .  44   n  of the mobile device  42  and receiving using M antennas  43   a,    43   b,    43   c,  . . .  43   m  of the base station  41 . Accordingly,  FIG. 2B  illustrates an example of N×M UL MIMO. 
     By increasing the level or order of MIMO, bandwidth of an uplink channel and/or a downlink channel can be increased. 
     MIMO communications are applicable to communication links of a variety of types, such as FDD communication links and TDD communication links. 
     Examples of Radio Frequency Electronics with Tunable Filter 
     Certain RF systems communicate using multiple communication standards, for instance, 4G LTE, 5G, and/or WiFi. One communication standard can specify communication over a frequency band that is relatively close in proximity to and/or overlapping in frequency with a frequency band of a different communication standard. In one example, LTE band B42 operates over a frequency range of about 3.4 GHz to 3.6 GHz, while 5G band n77 operates over a frequency range of about 3.3 GHz to 4.2 GHz. 
     To provide support for both frequency bands, an RF system can include an RF processing circuit supporting a frequency range covering both of the nearby bands of the different communication standards. For instance, with respect to LTE band B42 and 5G band n77, the RF processing circuit can be implemented to receive signals over a frequency range of about 3.3 GHz to 4.2 GHz, thereby supporting handling of both RF signals in LTE band B42 and RF signals in 5G band n77. 
     Although implementing an RF processing circuit in this manner lowers cost and/or area of the RF system by sharing resources and reducing component count, widening the bandwidth of the RF processing circuit can also increase exposure to blocker or jammer signals. 
     For example, in the context of an RF processing circuit that supports 3.3 GHz to 4.2 GHz to process both LTE band B42 and 5G band n77, a transmit signal from 5G band n79 (about 4.4 GHz to 5 GHz) can operate as a strong interferer for the RF processing circuit when receiving LTE band B42. In particular, since the RF processing circuit is implemented to cover not only the frequency range of LTE band B42 but also the frequency range of 5G band n77, the ability of the RF processing circuit to receive LTE band B42 is degraded in the presence of a 5G band n79 blocker or jammer signal. 
     RF systems with tunable filters are provided herein. In certain embodiments, an RF system includes a first RF processing circuit configured to process a first frequency band of a first communication standard and a second frequency band of a second communication standard. The first frequency band and the second frequency band are close in frequency and/or partially overlapping in frequency. The first RF processing circuit includes a tunable filter for changing the bandwidth of the first RF processing circuit to enhance the robustness of the first RF processing circuit to blocker or jammer signals of a third frequency band. 
     In certain implementations, the first RF processing circuit operates with a first bandwidth in a first mode and with a second bandwidth in a second mode. The first bandwidth can provide the first RF processing circuit with superior blocker protection, for instance, the first bandwidth can be narrower in frequency range to provide higher blocker immunity. In certain configurations, the first RF processing circuit also has a higher signal loss in the first mode relative to the second mode. In such configurations, the first RF processing circuit can have higher blocker suppression but lower receive sensitivity in the first mode relative to the second mode. 
     The first RF processing circuit can be controlled between the first mode and the second mode in a variety of ways. For example, in certain implementations, a system-level control circuit, such as a transceiver or baseband processor, controls mode selection, for instance, via digital data provided over an interface. 
     Mode can also be selected based at least in part on whether a presence of the blocker signal is detected. For instance, a detector can be included along an RF signal path through the first RF processing circuit and/or along another suitable RF signal path to monitor for presence of the blocker signal. 
     In certain implementations, the RF system further includes a second RF processing circuit that generates a transmit signal in the third frequency band. The transmit signal has the propensity to jam the first RF processing circuit when the first RF processing circuit is receiving the first frequency band. For instance, the blocker signal can arise from the transmit signal due to finite isolation of a frequency multiplexer (for instance, a diplexer, a triplexer, etc.) or other components (for instance, switches, duplexers, etc.) and/or from antenna-to-antenna coupling. To provide enhanced blocker suppression, selection between the first mode and the second mode can be based on whether the second RF processing circuit is transmitting. For example, the first mode can be selected when the second RF processing circuit is transmitting and the first RF processing circuit is receiving in the first frequency band. 
     The tunable filter can be implemented in a wide variety of ways, including using switches to control bandwidth. For example, in certain implementations, a shunt notch filter is switched in or out of an RF signal path through the first RF processing circuit to control bandwidth. 
       FIG. 3  is a schematic diagram of one embodiment of an RF system  80 . The RF system  80  includes a transceiver  50 , a first antenna  51 , a second antenna  52 , and a front end circuit  55 . Although  FIG. 3  illustrates one embodiment of an RF system, the teachings herein are applicable to RF systems implemented in a wide variety of ways. 
     The front end circuit  55  can provide a number of functionalities associated with, for example, MIMO communications, switching between different bands, carrier aggregation, switching between different power modes, filtering of signals, duplexing of signals, and/or some combination thereof. In the illustrated embodiment, the front end circuit  55  includes a first RF signal processing circuit  61 , a second RF signal processing circuit  62 , a third RF signal processing circuit  63 , and a diplexer  64 . 
     Although one embodiment of a front end circuit is shown, the teachings herein are applicable to front end circuits implemented in a wide variety of ways. A front end circuit, such as the front end circuit  55  of  FIG. 3 , is also referred to herein as a front end system. 
     As shown in  FIG. 3 , the first RF signal processing circuit  61  includes a tunable filter  67  and a low noise amplifier (LNA)  68  for amplifying a filtered signal generated by the tunable filter  67 . Additionally, the tunable filter  67  receives an input signal from the first antenna  51  via the diplexer  64 . In certain implementations, the first RF signal processing circuit  61  is implemented on a module, for instance, a multi-chip module (MCM). Although illustrated as including the tunable filter  67  and the LNA  68 , other implementations are possible, such as configurations in which the RF signal processing circuit  61  includes additional components, for instance, one or more switches, one or more power amplifiers, and/or other circuitry. 
     The second RF signal processing circuit  62  includes a first power amplifier  71 , which provides a first amplified RF signal to the first antenna  51  via the diplexer  64 . In certain implementations, the second RF signal processing circuit  62  is implemented on a module, for instance, an MCM. Although illustrated as including only the power amplifier  71 , the second RF signal processing circuit  62  can include additional components. 
     The third RF processing circuit  63  includes a second power amplifier  72 , which provides a second amplified RF signal to the second antenna  52 . In certain implementations, the third RF signal processing circuit  63  is implemented on a module, for instance, an MCM. Although illustrated as including only the power amplifier  72 , the third RF signal processing circuit  63  can include additional components. 
     As shown in  FIG. 3 , the front end circuit  55  is connected to the transceiver  50  by various connections, which can include one or more RF signal routes to the first RF signal processing circuit  61 , the second RF signal processing circuit  62 , and/or the third RF signal processing circuit  63 . In certain implementations, the connections further include a digital interface, such as a mobile industry processor interface radio frequency front end (MIPI RFFE) bus, an inter-integrated circuit (I 2 C) bus, and/or other suitable interface. 
     In the illustrated embodiment, the first RF signal processing circuit  61  is implemented to support reception of a first frequency band of a first communication standard and a second frequency band of a second communication standard. In one embodiment, the first frequency band is LTE B42 and the second frequency band is 5G n77. The first radio frequency processing circuit  61  includes the tunable filter  67  having adjustable bandwidth to control an amount of filtering provided to a blocker signal of a third frequency band. In one embodiment the third frequency band is 5G n79. 
     The blocker signal can arise from transmission within the RF system  80 . For example, the power amplifier  71  of the second RF processing circuit  62  and/or the power amplifier  72  of the third RF processing circuit  63  can generate a transmit signal in the third frequency band. Additionally or alternatively, antenna-to-antenna coupling  78  between the first antenna  51  and the second antenna  52  and/or leakage  79  from finite isolation of the diplexer  64  can lead to generation of the blocker signal. 
       FIG. 4A  is a schematic diagram of another embodiment of a front end circuit  100 . The front end circuit  100  includes an LTE/5G receive (Rx) module  101 , a 5G receive module  102 , a 5G transmit/receive (Tx/Rx) module  103 , a frequency multiplexer  104  (diplexer, in this example), a first antenna  105 , and a second antenna  106 . Although  FIG. 4A  illustrates one embodiment of an RF system, the teachings herein are applicable to RF systems implemented in a wide variety of ways. 
     In the illustrated embodiment, the LTE/5G receive module  101  includes an antenna pin  111 , a receive output pin  112 , a serial interface  114  (MIPI RFFE bus, in this example), a tunable filter  115 , and an LNA  116 . Additionally, the 5G receive module  102  includes an antenna pin  121 , a receive output pin  122 , a serial interface  124 , a bandpass filter  125 , and an LNA  126 . Furthermore, the 5G transmit/receive module  103  includes an antenna pin  131 , a receive output pin  132 , a transmit input pin  133 , a serial interface  134 , a bandpass filter  135 , an LNA  136 , and a power amplifier  137 . 
     Although various example implementations of the modules are shown, the teachings herein are applicable to other implementations of modules, including, for example, configurations including more or fewer components and/or a different arrangement of components. Additionally, although certain modules are indicated as having transmit and/or receive functionality, the modules can be adapted to provide functionality desired for a particular application and/or implementation. For example, in another embodiment the module  101  and/or the module  102  is also implemented with transmit functionality. 
     The front end circuit  100  illustrates one example of 5G/LTE jammer coupling  109  through antenna-to-antenna isolation. In the illustrated embodiment, the tunable filter  115  is included in the LTE/5G receive module  101  to provide coexistence. In certain implementations, the tunable filter  115  is implemented as a switchable 5G/LTE filter that provides for coexistence with close in proximity bands (for instance n79, in a frequency range of about 4.4 GHz to 5 GHz). In this example, B42 receiving occurs via the first antenna  105 , while n79 transmitting occurs via the second antenna  106 . 
       FIG. 4B  is a diagram showing one example of simulation results for the front end circuit  100  of  FIG. 4A . The simulation results include a first graph of wideband response versus frequency, and a second graph of insertion loss versus frequency. The simulation results correspond to one implementation of the tunable filter  115  implemented as a switchable 5G/LTE filter. Plots are included for each graph for the switchable 5G/LTE filter in a first mode and in a second mode. 
     For the illustrated embodiment, narrowing the bandwidth of the LTE/5G receive module  101  using the module&#39;s tunable filter results in not only narrower bandwidth, but also a greater amount of insertion loss. 
       FIG. 4C  is a schematic diagram of another embodiment of a front end circuit  150 . The front end circuit  150  includes an LTE/5G transmit/receive module  140 , a 5G transmit/receive module  103 , a diplexer  104 , and an antenna  105 . 
     In the illustrated embodiment, the LTE/5G transmit/receive module  140  includes an antenna pin  141 , a receive output pin  142 , a transmit input pin  143 , a serial interface  144 , a tunable filter  145 , an LNA  146 , a power amplifier  147 , and a switch  148 . Additionally, the 5G transmit/receive module  103  includes an antenna pin  131 , a receive output pin  132 , a transmit input pin  133 , a serial interface  134 , a bandpass filter  135 , an LNA  136 , and a power amplifier  137 . 
     Although various example implementations of the modules are shown, the teachings herein are applicable to other implementations of modules, including, for example, configurations including more or fewer components and/or a different arrangement of components. 
     The front end circuit  150  illustrates one example of 5G/LTE jammer coupling  149  through diplexer isolation. In the illustrated embodiment, the tunable filter  145  is included in the LTE/5G transmit/receive module  140  to provide coexistence. In certain implementations, the tunable filter  145  is implemented as a switchable 5G/LTE to provide for coexistence with close in proximity bands (for instance, n79). In this example, B42 receiving and n79 transmitting occurs via the antenna  105 . 
       FIG. 4D  is a schematic diagram of another embodiment of a front end circuit  1020 . The front end circuit  1020  includes an LTE/5G transmit/receive module  1010 , a 5G transmit/receive module  103 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1020  of  FIG. 4D  is similar to the front end circuit  150  of  FIG. 4C , except that the front end circuit  1020  includes an implementation of tunable filtering including multiple tunable filters. For example, in comparison to the LTE/5G transmit/receive module  140  of  FIG. 4C , the LTE/5G transmit/receive module  1010  of  FIG. 4D  includes both a first tunable filter  145  between the antenna pin  141  and the switch  148  and a second tunable filter  1015  between the switch  148  and an input to the LNA  146 . 
       FIG. 4E  is a schematic diagram of another embodiment of a front end circuit  1040 . The front end circuit  1040  includes an LTE/5G transmit/receive module  1030 , a 5G transmit/receive module  103 , a diplexer  104 , and an antenna  105 . The front end circuit  1040  of  FIG. 4E  is similar to the front end circuit  1020  of  FIG. 4D , except that the front end circuit  1040  includes an implementation of filtering including a fixed filter and a tunable filter. For example, in comparison to the LTE/5G transmit/receive module  1010  of  FIG. 4D  that includes two tunable filters, the LTE/5G transmit/receive module  1030  of  FIG. 4E  includes a tunable filter  1015  between the switch  148  and an input to the LNA  146  and a fixed filter  1016  between the antenna pin  141  and the switch  148 . 
       FIG. 4F  is a schematic diagram of another embodiment of a front end circuit  1060 . The front end circuit  1060  includes an LTE/5G transmit/receive module  1050 , a 5G transmit/receive module  103 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1060  of  FIG. 4F  is similar to the front end circuit  150  of  FIG. 4C , except that the front end circuit  1060  includes an implementation of tunable filtering in which separate tunable receive and tunable transmit filters are provided. For example, in comparison to the LTE/5G transmit/receive module  140  of  FIG. 4C , the LTE/5G transmit/receive module  1050  of  FIG. 4F  omits the tunable filter  145  in favor of including a tunable receive filter  1015  between a first throw of the switch  148  and an input to the LNA  146  and a tunable transmit filter  1017  between a second throw of the switch  148  and an output of the power amplifier  147 . 
       FIG. 4G  is a schematic diagram of another embodiment of a front end circuit  1080 . The front end circuit  1080  includes an LTE/5G transmit/receive module  1070 , a 5G transmit/receive module  1075 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1080  of  FIG. 4G  is similar to the front end circuit  1040  of  FIG. 4E , except that the front end circuit  1080  includes an implementation of switches with an additional throw for connecting to bypass terminals. For example, in comparison to the LTE/5G transmit/receive module  1030  of  FIG. 4E , the LTE/5G transmit/receive module  1070  of  FIG. 4G  includes a bypass terminal  1019  and a switch  1018  having a third throw coupled to the bypass terminal  1019 . Additionally, in comparison to the 5G transmit/receive module  103  of  FIG. 4E , the 5G transmit/receive module  1075  of  FIG. 4G  includes a bypass terminal  1039  and a switch  1038  having an additional throw coupled to the bypass terminal  1039 . 
     The bypass terminal  1019  and the bypass terminal  1039  can be used for a wide variety of functions. For example, in a 4×4 MIMO application, including the bypass terminals provides the ability to route any transmit signal to any of the four antennas for sounding the RF propagation channel of each antenna path to improve MIMO performance. 
       FIG. 4H  is a schematic diagram of another embodiment of a front end circuit  1090 . The front end circuit  1090  includes a LTE/5G receive module  1091  and a 5G receive module  1092 . 
     The LTE/5G receive module  1091  of  FIG. 4H  is similar to the LTE/5G receive module  101  of  FIG. 4A , except that the LTE/5G receive module  1091  further includes a switch  1093  and a bypass terminal  1019 . Additionally, the 5G receive module  1092  of  FIG. 4H  is similar to the 5G receive module  102  of  FIG. 4A , except that the 5G receive module  1092  further includes a switch  1094  and a bypass terminal  1039 . 
       FIG. 5A  is a schematic diagram of one embodiment of an RF module  160 . The RF module  160  includes an antenna pin  151 , a receive output pin  152 , a tunable filter  155 , and an LNA  156 . In the illustrated embodiment, the RF module  160  is an LTE/5G receive module. Although  FIG. 5A  illustrates one embodiment of an RF module, the teachings herein are applicable to RF modules implemented in a wide variety of ways. 
     In the illustrated embodiment, the tunable filter  155  includes a bandpass filter  157 , a shunt switch  158 , and a notch filter  159 . The shunt switch  158  and the notch filter  159  operate in combination with one another as a switchable notch filter circuit that controls a bandwidth processed by the RF module  160 . In certain implementations, the notch filter  159  provides a notch in frequency within the 5G n79 band. 
     The state of the shunt switch  158  operates to control the bandwidth of the RF module  160 . In certain implementations, tunable filter  155  passes a frequency range between about 3.4 GHz and about 3.8 GHz in a first state of the shunt switch  158 , and passes a frequency range between about 3.3 GHz and about 4.2 GHz in a second state of the shunt switch  158 . The state of the shunt switch  158  can be controlled in a wide variety of ways, including, but not limited to, via data received over a serial interface or bus. 
     Accordingly, in certain implementations, an RF module operates with a first bandwidth in a first mode and with a second bandwidth in a second mode. The first bandwidth can provide the RF module with superior blocker protection, for instance, the first bandwidth can be narrower in frequency range to provide higher blocker immunity. In certain configurations, the RF module also has a higher signal loss in the first mode relative to the second mode. In such configurations, the RF module can have higher blocker suppression but lower receive sensitivity in the first mode relative to the second mode. 
       FIG. 5B  is a schematic diagram of one embodiment of a notch filter circuit  180  for a tunable filter. The notch filter circuit  180  illustrates one example of a suitable notch filter circuit for providing frequency tuning. For example, the notch filter circuit  180  illustrates one implementation of the notch filter  159  of  FIG. 5A . 
     Although one implementation of a notch filter is shown, a notch filter can be implemented in a wide variety of ways. Furthermore, although a tunable filter can be implemented with a switchable notch filter, other implementations of tunable filters can be used. For example, the teachings herein are applicable to tunable filters implemented in a wide variety of ways, including, for example, tunable filters that operate without switchable notch filters. 
     In the illustrated embodiment, the notch filter  180  includes a signal port  170 , a first inductor  171 , a second inductor  172 , a capacitor  173 , and a termination circuit  174 . As shown in  FIG. 5B , the first inductor  171  and capacitor  173  are electrically connected in parallel with one another. Additionally, the parallel combination of the first inductor  171  and the capacitor  173  are connected in series with the second inductor  172  between the signal port  170  and ground. The termination circuit  174  is also connected between the signal port  170  and ground. 
     In certain implementations, the notch filter  180  is implemented to provide a notch in frequency in 5G n79. The component values of the notch filter  180  can have a wide variety of values, such as values selected for a particular application and/or implementation. In one example, the first inductor  171  has an inductance of about 1.7 nanohenry (nH), the second inductor  172  has an inductance of about 1.46 nH, the capacitor  173  has a capacitance of about 1.4 picofarad (pF), and the termination circuit  174  has an impedance of about 50 ohm. However, other implementations are possible. 
       FIG. 5C  is a diagram showing one example of simulation results for the RF module  160  of  FIG. 5A . The simulations correspond to an implementation of the RF module  160  in which the notch filter  159  in implemented using the notch filter circuit  180  of  FIG. 5B . The simulations include a graph of gain versus frequency and a Smith chart of the S-parameter S22. 
       FIG. 6A  is a schematic diagram of another embodiment of a front end circuit  210 . The front end circuit  210  includes a multi-band RF receive module  200 , a diplexer  104 , and an antenna  105 . 
     In the illustrated embodiment, the multi-band RF receive module  200  includes a first antenna pin  181 , a second antenna pin  191 , a first receive output pin  182 , a second receive output pin  192 , a serial interface  184 , a tunable filter  185 , a bandpass filter  195 , a first LNA  186 , and a second LNA  196 . Although one embodiment of an RF module is shown, the teachings herein are applicable to RF modules implemented in a wide variety of ways. 
     In certain implementations herein, multiple RF paths associated with different frequency bands are collocated on a common module. Such a common module can include one or more semiconductor dies. 
     In the illustrated embodiment, a first RF path processes LTE B42/5G n77, and includes the tunable filter  185  and the first LNA  186 . Additionally, a second RF path processes 5G n79, and includes the bandpass filter  195  and the second LNA  196 . Thus, the multi-band RF module  210  is a LTE/5G receive module, in this embodiment. 
       FIG. 6B  is a schematic diagram of another embodiment of a front end circuit  240 . The front end circuit  240  includes a multi-band RF transmit/receive module  220 , a diplexer  104 , and an antenna  105 . The multi-band RF transmit/receive module  220  illustrates another example of an RF module including multiple RF paths associated with different frequency bands that are collocated on a common module. 
     In the illustrated embodiment, the multi-band RF transmit/receive module  220  includes a first antenna pin  201 , a second antenna pin  211 , a first receive output pin  202 , a second receive output pin  212 , a first transmit input pin  203 , a second transmit input pin  213 , a serial interface  204 , a tunable filter  205 , a bandpass filter  215 , a first LNA  206 , a second LNA  216 , a first power amplifier  207 , a second power amplifier  217 , a first switch  208 , and second switch  218 . Although one embodiment of an RF module is shown, the teachings herein are applicable to RF modules implemented in a wide variety of ways. 
     In the illustrated embodiment, a first RF path transmits/receives LTE B42/5G n77, and includes the tunable filter  205  and the first switch  208 , which selectively connects the tunable filter  205  to an input of the first LNA  206  or to an output of the first power amplifier  207 . Additionally, a second RF path transmits/receives 5G n79, and includes the bandpass filter  215  and the second switch  218 , which selectively connects the bandpass filter  215  to an input of the second LNA  216  or to an output of the second power amplifier  217 . Thus, the multi-band RF module  220  is a LTE/5G transmit/receive module, in this embodiment. 
     As shown in  FIG. 6B , 5G/LTE jammer coupling  219  can arise through diplexer isolation. 
       FIG. 6C  is a schematic diagram of another embodiment of a front end circuit  1120 . The front end circuit  1120  includes a multi-band RF transmit/receive module  1110 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1120  of  FIG. 6C  is similar to the front end circuit  240  of  FIG. 6B , except that the front end circuit  1120  includes an implementation of tunable filtering including multiple tunable filters. For example, in comparison to the multi-band RF transmit/receive module  220  of  FIG. 6B , the multi-band RF transmit/receive module  1110  of  FIG. 6C  includes both a first tunable filter  205  between the first antenna pin  201  and the switch  208  and a second tunable filter  1115  between the switch  208  and an input to the LNA  206 . 
       FIG. 6D  is a schematic diagram of another embodiment of a front end circuit  1140 . The front end circuit  1140  includes a multi-band RF transmit/receive module  1130 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1140  of  FIG. 6D  is similar to the front end circuit  1120  of  FIG. 6C , except that the front end circuit  1140  includes an implementation of filtering including a fixed filter and a tunable filter. For example, in comparison to the multi-band RF transmit/receive module  1110  of  FIG. 6C  that includes two tunable filters, the multi-band RF transmit/receive module  1130  of  FIG. 6D  includes a tunable filter  1115  between the switch  208  and an input to the LNA  206  and a fixed filter  1116  between the first antenna pin  201  and the switch  208 . 
       FIG. 6E  is a schematic diagram of another embodiment of a front end circuit  1160 . The front end circuit  1160  includes a multi-band RF transmit/receive module  1150 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1160  of  FIG. 6E  is similar to the front end circuit  240  of  FIG. 6B , except that the front end circuit  1160  includes an implementation of tunable filtering in which separate tunable receive and tunable transmit filters are provided. For example, in comparison to the multi-band RF transmit/receive module  220  of  FIG. 6B , the multi-band RF transmit/receive module  1150  of  FIG. 6E  omits the tunable filter  205  in favor of including a tunable receive filter  1115  between a first throw of the switch  208  and an input to the LNA  206  and a tunable transmit filter  1117  between a second throw of the switch  208  and an output of the power amplifier  207 . 
       FIG. 6F  is a schematic diagram of another embodiment of a front end circuit  1180 . The front end circuit  1180  includes a multi-band RF transmit/receive module  1170 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1180  of  FIG. 6F  is similar to the front end circuit  1140  of  FIG. 6D , except that the front end circuit  1180  includes an implementation of switches with an additional throw for connecting to bypass terminals. For example, in comparison to the multi-band RF transmit/receive module  1130  of  FIG. 6D , the multi-band RF transmit/receive module  1170  of  FIG. 6F  includes a bypass terminal  1119  and a switch  1118  having a third throw coupled to the bypass terminal  1119  and a switch  1128  having an additional throw coupled to the bypass terminal  1129 . 
       FIG. 6G  is a schematic diagram of another embodiment of a front end circuit  250 . The front end circuit  250  includes a first multi-band RF transmit/receive module  220   a,  a first diplexer  104   a,  a first antenna  105   a,  a second multi-band RF transmit/receive module  220   b,  a second diplexer  104   b,  a second antenna  105   b,  a first multi-band RF receive module  200   a,  a third diplexer  104   c,  a third antenna  105   c,  a second multi-band RF receive module  200   b,  a fourth diplexer  104   d , and a fourth antenna  105   d.    
     In the illustrated embodiment, the first multi-band RF receive module  200   a  and the second multi-band RF receive module  200   b  are implemented as described above with respect to the multi-band RF receive module  200  of  FIG. 6A . For example, the first multi-band RF receive module  200   a  includes a first antenna pin  181   a,  a second antenna pin  191   a,  a first receive output pin  182   a,  a second receive output pin  192   a,  a serial interface  184   a,  a tunable filter  185   a,  a bandpass filter  195   a , a first LNA  186   a,  and a second LNA  196   a.  Additionally, the second multi-band RF receive module  200   b  includes a first antenna pin  181   b,  a second antenna pin  191   b,  a first receive output pin  182   b,  a second receive output pin  192   b,  a serial interface  184   b , a tunable filter  185   b,  a bandpass filter  195   b,  a first LNA  186   b,  and a second LNA  196   b.    
     With continuing reference to  FIG. 6G , the first multi-band RF transmit/receive module  220   a  and the second multi-band RF transmit/receive module  220   b  are implemented as described above with respect to the multi-band RF transmit/receive module  220  of  FIG. 6B . For example, the first multi-band RF transmit/receive module  220   a  includes a first antenna pin  201   a,  a second antenna pin  211   a,  a first receive output pin  202   a,  a second receive output pin  212   a,  a first transmit input pin  203   a,  a second transmit input pin  213   a,  a serial interface  204   a,  a tunable filter  205   a,  a bandpass filter  215   a,  a first LNA  206   a,  a second LNA  216   a,  a first power amplifier  207   a,  a second power amplifier  217   a,  a first switch  208   a,  and second switch  218   a.  Additionally, the second multi-band RF transmit/receive module  220   b  includes a first antenna pin  201   b,  a second antenna pin  211   b,  a first receive output pin  202   b , a second receive output pin  212   b,  a first transmit input pin  203   b,  a second transmit input pin  213   b,  a serial interface  204   b,  a tunable filter  205   b,  a bandpass filter  215   b,  a first LNA  206   b,  a second LNA  216   b,  a first power amplifier  207   b,  a second power amplifier  217   b,  a first switch  208   b,  and second switch  218   b.    
     In the illustrated embodiment, the front end circuit  250  is implemented to operate with n77/B42 4×4 DL MIMO and n79 2×2 UL MIMO. The teachings herein are applicable to RF systems operating using DL MIMO and/or UL MIMO of a wide variety of orders. 
     As shown in  FIG. 6G , various jammers can be present when using MIMO. For example, when the power amplifier  217   a  is transmitting, a first jammer signal  248   a  can reach the antenna pin  201   a  of the module  220   a,  a second jammer signal  248   b  can reach the antenna pin  201   b  of the module  220   b,  a third jammer signal  248   c  can reach the antenna pin  181   b  of the module  200   b,  and a fourth jammer signal  248   d  can reach the antenna pin  181   a  of the module  200   a.  Additionally, when the power amplifier  217   b  is transmitting, a first jammer signal  249   a  can reach the antenna pin  201   b  of the module  220   b,  a second jammer signal  249   b  can reach the antenna pin  201   a  of the module  220   a,  a third jammer signal  249   c  can reach the antenna pin  181   a  of the module  200   a,  and a fourth jammer signal  249   d  can reach the antenna pin  181   b  of the module  200   b.    
       FIG. 6H  is a schematic diagram of another embodiment of a front end circuit  1210 . The front end circuit  1210  of  FIG. 6H  is similar to the front end circuit  250  of  FIG. 6G , except that the front end circuit  1210  omits the first multi-band RF transmit/receive module  220   a  and the second multi-band RF transmit/receive module  220   b  in favor of including a first multi-band RF transmit/receive module  1110   a  and a second multi-band RF transmit/receive module  1110   b.  The first multi-band RF transmit/receive module  1110   a  and the second multi-band RF transmit/receive module  1110   b  are implemented in accordance with the multi-band RF transmit/receive module  1110  of  FIG. 6C . 
       FIG. 6I  is a schematic diagram of another embodiment of a front end circuit  1220 . The front end circuit  1220  of  FIG. 6I  is similar to the front end circuit  250  of  FIG. 6G , except that the front end circuit  1220  omits the first multi-band RF transmit/receive module  220   a  and the second multi-band RF transmit/receive module  220   b  in favor of including a first multi-band RF transmit/receive module  1130   a  and a second multi-band RF transmit/receive module  1130   b.  The first multi-band RF transmit/receive module  1130   a  and the second multi-band RF transmit/receive module  1130   b  are implemented in accordance with the multi-band RF transmit/receive module  1130  of  FIG. 6D . 
       FIG. 6J  is a schematic diagram of another embodiment of a front end circuit  1230 . The front end circuit  1230  of  FIG. 6J  is similar to the front end circuit  250  of  FIG. 6G , except that the front end circuit  1230  omits the first multi-band RF transmit/receive module  220   a  and the second multi-band RF transmit/receive module  220   b  in favor of including a first multi-band RF transmit/receive module  1150   a  and a second multi-band RF transmit/receive module  1150   b.  The first multi-band RF transmit/receive module  1150   a  and the second multi-band RF transmit/receive module  1150   b  are implemented in accordance with the multi-band RF transmit/receive module  1150  of  FIG. 6E . 
       FIG. 6K  is a schematic diagram of another embodiment of a front end circuit  1240 . 
     The front end circuit  1240  of  FIG. 6K  is similar to the front end circuit  250  of  FIG. 6G , except that the front end circuit  1240  omits the first multi-band RF transmit/receive module  220   a  and the second multi-band RF transmit/receive module  220   b  in favor of including a first multi-band RF transmit/receive module  1170   a  and a second multi-band RF transmit/receive module  1170   b.  The first multi-band RF transmit/receive module  1170   a  and the second multi-band RF transmit/receive module  1170   b  are implemented in accordance with the multi-band RF transmit/receive module  1170  of  FIG. 6F . 
     Furthermore, the front end circuit  1240  of  FIG. 6K  omits the first multi-band RF receive module  200   a  and the second multi-band RF receive module  200   b  of  FIG. 6G  in favor of including a first multi-band RF receive module  1255   a  and a second multi-band RF receive module  1255   b.  The first multi-band RF receive module  1255   a  of  FIG. 6K  is similar to the first multi-band RF receive module  200   a  of  FIG. 6G , except that the first multi-band RF receive module  1255   a  further includes a switch  1093   a,  a switch  1094   a,  a bypass terminal  1019   a,  and a bypass terminal  1039   a.  Additionally, the second multi-band RF receive module  1255   b  of  FIG. 6K  is similar to the second multi-band RF receive module  200   b  of  FIG. 6G , except that the second multi-band RF receive module  1255   b  further includes a switch  1093   b,  a switch  1094   b,  a bypass terminal  1019   b,  and a bypass terminal  1039   b.    
     As shown in  FIG. 6K , the bypass terminal  1119   a  of the first multi-band RF transmit/receive module  1170   a  is electrically connected to the bypass terminal  1019   a  of the first multi-band RF receive module  1255   a,  and the bypass terminal  1129   a  of the first multi-band RF transmit/receive module  1170   a  is electrically connected to the bypass terminal  1039   a  of the first multi-band RF receive module  1255   a.  Additionally, the bypass terminal  1119   b  of the second multi-band RF transmit/receive module  1170   b  is electrically connected to the bypass terminal  1019   b  of the second multi-band RF receive module  1255   b,  and the bypass terminal  1129   b  of the second multi-band RF transmit/receive module  1170   b  is electrically connected to the bypass terminal  1039   b  of the second multi-band RF receive module  1255   b.    
     Implementing the front end circuit  1240  in this manner provides the ability to route any transmit signal to any of the four antennas for sounding the RF propagation channel of each antenna path to improve MIMO performance. 
     As shown in  FIG. 6K , various jammers can be present when using MIMO. For example, when the power amplifier  217   a  is transmitting, a first jammer signal  248   a  can reach the antenna pin  201   a  of the module  1170   a,  a second jammer signal  248   b  can reach the antenna pin  201   b  of the module  1170   b,  a third jammer signal  248   c  can reach the antenna pin  181   b  of the module  1255   b,  and a fourth jammer signal  248   d  can reach the antenna pin  181   a  of the module  1255   a.  Furthermore, inclusion of the bypass terminal  1129   a  on the module  1170   a  gives rise to a fifth jammer signal  248   e  that can reach the antenna pin  181   a  of the module  1255   a . Additionally, when the power amplifier  217   b  is transmitting, a first jammer signal  249   a  can reach the antenna pin  201   b  of the module  1170   b,  a second jammer signal  249   b  can reach the antenna pin  201   a  of the module  1170   a,  a third jammer signal  249   c  can reach the antenna pin  181   a  of the module  1255   a,  and a fourth jammer signal  249   d  can reach the antenna pin  181   b  of the module  1255   b.  Furthermore, inclusion of the bypass terminal  1129   b  on the module  1170   b  gives rise to a fifth jammer signal  249   e  that can reach the antenna pin  181   b  of the module  1255   b.    
       FIG. 7A  is a schematic diagram of another embodiment of a front end circuit  330 . The front end circuit  330  includes a 5G receive module  301 , a WiFi/LAA transmit/receive module  302 , a diplexer  104 , and an antenna  105 . 
     In the illustrated embodiment, the 5G receive module  301  includes an antenna pin  311 , a receive output pin  312 , a serial interface  314 , a tunable filter  315 , and an LNA  316 . Additionally, the WiFi/LAA transmit/receive module  302  includes an antenna pin  321 , a receive output pin  322 , a transmit input pin  323 , a serial interface  324 , a bandpass filter  325 , an LNA  326 , a power amplifier  327 , and a switch  328 . 
     Although various example implementations of the modules are shown, the teachings herein are applicable to other implementations of modules, including, for example, configurations including more or fewer components and/or a different arrangement of components. 
     The front end circuit  330  illustrates one embodiment of a front end circuit in which a 5G receive module includes a tunable filter for providing blocker suppression to a jammer signal  309  from a WiFi/LAA module. 
       FIG. 7B  is a schematic diagram of another embodiment of a front end circuit  350 . The front end circuit  350  includes a 5G transmit/receive module  303 , a WiFi/LAA transmit/receive module  304 , a diplexer  104 , and an antenna  105 . 
     In the illustrated embodiment, the 5G transmit/receive module  303  includes an antenna pin  331 , a receive output pin  332 , a transmit input pin  333 , a serial interface  334 , a tunable filter  335 , an LNA  336 , a power amplifier  337 , and a switch  338 . Additionally, the WiFi/LAA transmit/receive module  304  includes an antenna pin  341 , a receive output pin  342 , a transmit input pin  343 , a serial interface  344 , a tunable filter  345 , an LNA  346 , a power amplifier  347 , and a switch  348 . 
     Although various example implementations of the modules are shown, the teachings herein are applicable to other implementations of modules, including, for example, configurations including more or fewer components and/or a different arrangement of components. 
     The front end circuit  350  illustrates one embodiment of a front end circuit in which a 5G transmit/receive module includes a tunable filter for providing blocker suppression to a jammer signal  319  from a WiFi/LAA module, and in which a WiFi/LAA module includes a tunable filter for providing blocker suppression to a jammer signal  320  from the 5G transmit/receive module. 
       FIG. 7C  is a schematic diagram of another embodiment of a front end circuit  1320 . The front end circuit  1320  includes a 5G transmit/receive module  1310 , a WiFi/LAA transmit/receive module  304 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1320  of  FIG. 7C  is similar to the front end circuit  350  of  FIG. 7B , except that the front end circuit  1320  includes an implementation of 5G transmit/receive tunable filtering including multiple tunable filters. For example, in comparison to the 5G transmit/receive module  303  of  FIG. 7B , the 5G transmit/receive module  1310  of  FIG. 7C  includes both a first tunable filter  335  between the antenna pin  331  and the switch  338  and a second tunable filter  1315  between the switch  338  and an input to the LNA  336 . 
       FIG. 7D  is a schematic diagram of another embodiment of a front end circuit  1340 . The front end circuit  1340  includes a 5G transmit/receive module  1330 , a WiFi/LAA transmit/receive module  304 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1340  of  FIG. 7D  is similar to the front end circuit  1320  of  FIG. 7C , except that the front end circuit  1340  includes an implementation of 5G transmit/receive filtering including a fixed filter and a tunable filter. For example, in comparison to 5G transmit/receive module  1310  of  FIG. 7C  that includes two tunable filters, the 5G transmit/receive module  1330  of  FIG. 7D  includes a tunable filter  1315  between the switch  338  and an input to the LNA  336  and a fixed filter  1316  between the antenna pin  331  and the switch  338 . 
       FIG. 7E  is a schematic diagram of another embodiment of a front end circuit  1360 . The front end circuit  1360  includes a 5G transmit/receive module  1350 , a WiFi/LAA transmit/receive module  304 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1360  of  FIG. 7E  is similar to the front end circuit  350  of  FIG. 7B , except that the front end circuit  1360  includes an implementation of 5G transmit/receive tunable filtering in which separate tunable receive and tunable transmit filters are provided. For example, in comparison to the 5G transmit/receive module  303  of  FIG. 7B , the 5G transmit/receive module  1350  of  FIG. 7E  omits the tunable filter  335  in favor of including a tunable receive filter  1315  between a first throw of the switch  338  and an input to the LNA  336  and a tunable transmit filter  1317  between a second throw of the switch  338  and an output of the power amplifier  337 . 
       FIG. 7F  is a schematic diagram of another embodiment of a front end circuit  1380 . The front end circuit  1380  includes a 5G transmit/receive module  1370 , a WiFi/LAA transmit/receive module  1375 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1380  of  FIG. 7F  is similar to the front end circuit  1340  of  FIG. 7D , except that the front end circuit  1380  includes an implementation of switches with an additional throw for connecting to bypass terminals. For example, in comparison to the 5G transmit/receive module  1330  of  FIG. 7D , the 5G transmit/receive module  1370  of  FIG. 7F  includes a bypass terminal  1319  and a switch  1318  having a third throw coupled to the bypass terminal  1319 . Additionally, in comparison to the WiFi/LAA transmit/receive module  304  of  FIG. 7D , the WiFi/LAA transmit/receive module  1375  of  FIG. 7F  includes a bypass terminal  1329  and a switch  1328  having an additional throw coupled to the bypass terminal  1329 . 
       FIG. 7G  is a schematic diagram of another embodiment of a front end circuit  1420 . The front end circuit  1420  includes a 5G transmit/receive module  303 , a WiFi/LAA transmit/receive module  1410 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1420  of  FIG. 7G  is similar to the front end circuit  350  of  FIG. 7B , except that the front end circuit  1420  includes an implementation of WiFi/LAA tunable filtering including multiple tunable filters. For example, in comparison to the WiFi/LAA transmit/receive module  304  of  FIG. 7B , the WiFi/LAA transmit/receive module  1410  of  FIG. 7G  includes both a first tunable filter  345  between the antenna pin  341  and the switch  348  and a second tunable filter  1415  between the switch  348  and an input to the LNA  346 . 
     The illustrated front end circuit  1420  of  FIG. 7G  includes the 5G transmit/receive module  303  of  FIG. 7B . However, the 5G transmit/receive module can be implemented in a wide variety of ways, including, but not limited to, using any of the embodiments of  FIGS. 7C-7F . 
       FIG. 7H  is a schematic diagram of another embodiment of a front end circuit  1440 . The front end circuit  1440  includes a 5G transmit/receive module  303 , a WiFi/LAA transmit/receive module  1430 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1440  of  FIG. 7H  is similar to the front end circuit  1420  of  FIG. 7G , except that the front end circuit  1440  includes an implementation of WiFi/LAA filtering including a fixed filter and a tunable filter. For example, in comparison to WiFi/LAA transmit/receive module  1410  of  FIG. 7G  that includes two tunable filters, the WiFi/LAA transmit/receive module  1430  of  FIG. 7H  includes a tunable filter  1415  between the switch  348  and an input to the LNA  346  and a fixed filter  1416  between the antenna pin  341  and the switch  348 . 
     The illustrated front end circuit  1440  of  FIG. 7H  includes the 5G transmit/receive module  303  of  FIG. 7B . However, the 5G transmit/receive module can be implemented in a wide variety of ways, including, but not limited to, using any of the embodiments of  FIGS. 7C-7F . 
       FIG. 7I  is a schematic diagram of another embodiment of a front end circuit  1460 . The front end circuit  1460  includes a 5G transmit/receive module  303 , a WiFi/LAA transmit/receive module  1450 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1460  of  FIG. 7I  is similar to the front end circuit  350  of  FIG. 7B , except that the front end circuit  1460  includes an implementation of WiFi/LAA tunable filtering in which separate tunable receive and tunable transmit filters are provided. For example, in comparison to the WiFi/LAA transmit/receive module  304  of  FIG. 7B , the WiFi/LAA transmit/receive module  1450  of  FIG. 7I  omits the tunable filter  345  in favor of including a tunable receive filter  1415  between a first throw of the switch  348  and an input to the LNA  346  and a tunable transmit filter  1417  between a second throw of the switch  348  and an output of the power amplifier  347 . 
     The illustrated front end circuit  1460  of  FIG. 7I  includes the 5G transmit/receive module  303  of  FIG. 7B . However, the 5G transmit/receive module can be implemented in a wide variety of ways, including, but not limited to, using any of the embodiments of  FIGS. 7C-7F . 
       FIG. 7J  is a schematic diagram of another embodiment of a front end circuit  1480 . The front end circuit  1480  includes a 5G transmit/receive module  1475 , a WiFi/LAA transmit/receive module  1470 , a diplexer  104 , and an antenna  105 . 
     The front end circuit  1480  of  FIG. 7J  is similar to the front end circuit  1440  of  FIG. 7H , except that the front end circuit  1480  includes an implementation of switches with an additional throw for connecting to bypass terminals. For example, in comparison to the WiFi/LAA transmit/receive module  1430  of  FIG. 7H , the WiFi/LAA transmit/receive module  1470  of  FIG. 7J  includes a bypass terminal  1419  and a switch  1418  having a third throw coupled to the bypass terminal  1419 . Additionally, in comparison to the 5G transmit/receive module  303  of  FIG. 7H , the 5G transmit/receive module  1475  of  FIG. 7J  includes a bypass terminal  1479  and a switch  1478  having an additional throw coupled to the bypass terminal  1479 . 
       FIG. 8A  is a schematic diagram of another embodiment of a front end circuit  430 . The front end circuit  430  includes an antenna  105 , an RF processing circuit  401 , a blocker detector  408 , and a serial interface controller  409  (a MIPI controller, in this example). 
     As shown in  FIG. 8A , the RF processing circuit  401  includes a tunable filter  411  and an LNA  412  in cascade, in this embodiment. Additionally, the RF processing circuit  401  processes an RF signal received from the antenna  105  to generate an RF receive signal (RX). Although one embodiment of an RF processing circuit is depicted, the front end circuit  430  can be modified to include any of the RF processing circuits herein. 
     In the illustrated embodiment, the tunable filter  411  of the RF processing circuit  401  is controlled based on an amount of blocker that is sensed or detected by the blocker detector  408 . The blocker detector  408  is positioned along an RF signal path through the RF processing circuit  401 , in this embodiment. 
       FIG. 8B  is a schematic diagram of another embodiment of a front end circuit  440 . The front end circuit  440  includes a first RF processing circuit  401 , a second RF processing circuit  402 , a diplexer  104 , an antenna  105 , a blocker detector  408 , and a serial interface controller  409 . 
     As shown in  FIG. 8B , the first RF processing circuit  401  includes a tunable filter  411  and an LNA  412  in cascade. Additionally, the first RF processing circuit  401  generates a first RF receive signal (RX 1 ) based on processing a first RF signal received from a first signal port of the diplexer  104 . The second RF processing circuit  402  includes a bandpass filter  421  and an LNA  422  in cascade. Additionally, the second RF processing circuit  402  generates a second RF receive signal (RX 2 ) based on processing a second RF signal received from a second signal port of the diplexer  104 . Although specific embodiments of RF processing circuits are depicted, the front end circuit  440  can be modified to include any of the RF processing circuits herein. 
     In the illustrated embodiment, the blocker detector  408  senses a blocker signal level along an RF signal path through the second RF processing circuit  402 , and the detected blocker level is used to control the tunable filter  411  in the first RF processing circuit  401 . 
       FIG. 8C  is a schematic diagram of another embodiment of a front end circuit  450 . The front end circuit  450  includes an antenna  105 , an RF processing circuit  401 , and a serial interface controller  447  (a MIPI controller, in this example). Although one embodiment of an RF processing circuit is depicted, the front end circuit  450  can be modified to include any of the RF processing circuits herein. 
     As shown in  FIG. 8C , the serial interface controller  447  controls the tunable filter  411  of the RF processing circuit  401  based on system level information, such as band information (BAND SELECT), channel information (CHANNEL INFO), and/or radio access network information (RAN INFO). 
       FIG. 9  is a schematic diagram of another embodiment of an RF system  500 . The RF system  500  includes a front end circuit  501  and a transceiver  502 . 
     In the illustrated embodiment, the front end circuit  501  includes RF signal input terminals  511   a,    511   b,  . . .  511   m,  RF signal output terminals  512   a,    512   b , . . .  512   m,  tunable input filters  515   a,    515   b,  . . .  515   m,  LNAs  516   a,    516   b,  . . .  516   m , tunable output filters  517   a,    517   b,  . . .  517   m.  As shown in  FIG. 9 , the front end circuit  501  outputs RF receive signals RXa, RXb, . . . RXm on the RF signal output terminals  512   a,    512   b,  . . .  512   m,  respectively. 
     The front end circuit  501  includes m signal paths, where m is an integer greater than or equal to one. Additionally, each RF signal path includes a cascade of a first tunable filter, an LNA, and a second tunable filter, in this embodiment. Including an additional tunable filter along a signal path between an output of an LNA and an input to a transceiver aids in protecting the transceiver from desense. 
     Although one example of RF signal paths through a front end circuit is shown, a front end circuit can include RF signal paths implemented with other configurations of circuitry. Additionally, in implementations in which a front end circuit includes two or more RF signal paths, the implementation of each RF signal path need not be the same. Rather, each RF signal path can include circuitry desirable for a particular implementation or application. 
     In certain implementations, the front end circuit  501  corresponds to a semiconductor die, and the RF signal input terminals  511   a,    511   b,  . . .  511   m  and the RF signal output terminals  512   a,    512   b,  . . .  512   m  correspond to pins of the die. A pin of a semiconductor die is also referred to herein as a pad. 
     In the illustrated embodiment, the transceiver  502  includes amplifiers  521   a,    521   b,  . . .  521   m  for amplifying the RF receive signals RXa, RXb, . . . RXm, respectively, from the front end circuit  501 . Additionally, the transceiver  502  includes a multiplexing circuit  522 , local oscillators (LOs)  531   a,    531   b,    531   c,    531   d,  . . .  531   n , downconverting mixers  532   a,    532   b,    532   c,    532   d,  . . .  532   n,  and filters  533   a,    533   b,    533   c ,  533   d,  . . .  533   n.    
     The multiplexing circuit  522  operates to select, combine, split, filter and/or otherwise process the amplified RF receive signals RXa, RXb, . . . RXm to generate input signals to the downconverting mixers  532   a,    532   b,    532   c,    532   d,  . . .  532   n . As shown in  FIG. 9 , the multiplexing circuit  522  receives m signals and outputs n signals, where m and n are each integers greater than equal to one. The integers m and n need not be the same, but rather m can be greater than n or m can be less than n. 
     Although certain embodiments have been illustrated and described in the context of specific frequency bands and communication standards, skilled artisans will appreciate that the teachings herein are applicable to a variety of bands and communication standards. 
     In a first example, n79 serves as a blocker to B42. For instance, B42 (about 3.4-3.6 GHz) can operate using a same path as n77 (about 3.3-4.2 GHz), and n79 (about 4.4-5 GHz) can serve as a blocker or jammer to receiving B42. For instance, distance between bands with no tuning is about 200 MHz, while distance between bands with tuning is about 800 MHz. 
     In a second example, 5 GHz WiFi serves as a blocker to n79. For instance, 5 GHz WiFi (about 5.18-5.95 GHz) can serve as a blocker or jammer to receiving n79 (about 4.4-5 GHz). For instance, distance between bands with no tuning is about 180 MHz, while distance between bands with tuning is a function of WiFi/cellular channel. 
     In a third example, 2.4 GHz WiFi serves as a blocker to B40. For instance, 2.4 GHz WiFi (about 2.4-2.482 GHz) can serve as a blocker or jammer to receiving B40 (about 2.3-2.4 GHz). The distance between bands with no tuning is about 0 MHz, while the distance between bands with tuning is a function of WiFi/cellular channel. 
     In a fourth example, 2.4 GHz WiFi (about 2.4-2.482 GHz) serves as a blocker or jammer to receiving B41 (about 2.496-2.690 GHz). The distance between bands with no tuning is about 14 MHz, while the distance between bands with tuning is a function of WiFi/cellular channel. 
     In a fifth example, 2.4 GHz WiFi (about 2.4-2.482 GHz) serves as a blocker or jammer to B7 Tx (about 2.500-2.570 GHz). The distance between bands with no tuning is about 18 MHz, while the distance between bands with tuning is a function of WiFi/cellular channel. 
     In a sixth example, B11/21 Tx (about 1.427-1.463 GHz) serves as a blocker or jammer to B32+B11/21 Rx (about 1.452-1.511 GHz, with B32 in a range of 1.452-1.496 GHz and B11/21 in a range of about 1.476-1.511 GHz). The distance between bands with no tuning is about −11 MHz, while the distance between bands with tuning is about 13 MHz. 
     Although six examples have been provided above, the teachings herein are applicable to a variety of configurations, including, but not limited to, any scenario where frequency bands share a common RF signal path and have different coexistence conditions. 
       FIG. 10  is a schematic diagram of another embodiment of an RF system  660 . The RF system  660  further includes a transceiver  641 , power amplifier circuitry  642 , transmit filter circuitry  643 , receive filter circuitry  644 , LNA circuitry  645 , antenna switch circuitry  646 , coupler circuitry  647 , sensor circuitry  648 , power management circuitry  649 , an antenna  650 , and a MIPI RFFE bus  651 . 
     As shown in  FIG. 10 , various components of the RF system  660  are interconnected by the MIPI RFFE bus  651 . Additionally, the transceiver  641  includes a master device of the MIPI RFFE bus  651 , and each of the RF components includes a slave device of the MIPI RFFE bus  651 . The master device of the transceiver  641  sends control commands over the MIPI RFFE bus  651  to configure the RF system  660  during initialization and/or while operational. 
     The power amplifier circuitry  642  can include one or more power amplifiers. As shown in  FIG. 10 , the power amplifier circuitry  642  receives one or more power amplifier supply voltages from the power management circuitry  649 . 
     In certain implementations, the receive filter circuitry  644  includes one or more tunable filters implemented in accordance with the teachings herein. Additionally, the tunable filters are controlled by data receiver over the MIPI RFFE bus  651 . Furthermore, in certain implementations, the transmit filter circuitry  643  includes one or more tunable filters implemented in accordance with the teachings herein. 
     Although  FIG. 10  illustrates one example of an RF system, the teachings herein are applicable to RF systems implemented in a wide variety of ways. 
       FIG. 11  is a schematic diagram of one embodiment of a mobile device  800 . The mobile device  800  includes a baseband system  801 , a transceiver  802 , a front end circuit  803 , antennas  804 , a power management system  805 , a memory  806 , a user interface  807 , and a battery  808 . 
     The mobile device  800  can be used communicate using a wide variety of communications technologies, including, but not limited to, 2G, 3G, 4G (including LTE, LTE-Advanced, and LTE-Advanced Pro), 5G NR, WLAN (for instance, WiFi), WPAN (for instance, Bluetooth and ZigBee), WMAN (for instance, WiMax), and/or GPS technologies. 
     The transceiver  802  generates RF signals for transmission and processes incoming RF signals received from the antennas  804 . It will be understood that various functionalities associated with the transmission and receiving of RF signals can be achieved by one or more components that are collectively represented in  FIG. 11  as the transceiver  802 . In one example, separate components (for instance, separate circuits or dies) can be provided for handling certain types of RF signals. 
     The front end circuit  803  aids is conditioning signals transmitted to and/or received from the antennas  804 . In the illustrated embodiment, the front end circuit  803  includes power amplifiers (PAs)  811 , low noise amplifiers (LNAs)  812 , filters  813 , switches  814 , and duplexers  815 . However, other implementations are possible. 
     For example, the front end circuit  803  can provide a number of functionalities, including, but not limited to, amplifying signals for transmission, amplifying received signals, filtering signals, switching between different bands, switching between different power modes, switching between transmission and receiving modes, duplexing of signals, multiplexing of signals (for instance, diplexing or triplexing), or some combination thereof. 
     The front end circuit  803  can be implemented to include one or more radio frequency processing circuits with tunable filters in accordance with the teachings herein. 
     In certain implementations, the mobile device  800  supports carrier aggregation, thereby providing flexibility to increase peak data rates. Carrier aggregation can be used for both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD), and may be used to aggregate a plurality of carriers or channels. Carrier aggregation includes contiguous aggregation, in which contiguous carriers within the same operating frequency band are aggregated. Carrier aggregation can also be non-contiguous, and can include carriers separated in frequency within a common band or in different bands. 
     The antennas  804  can include antennas used for a wide variety of types of communications. For example, the antennas  804  can include antennas for transmitting and/or receiving signals associated with a wide variety of frequencies and communications standards. 
     In certain implementations, the antennas  804  support MIMO communications and/or switched diversity communications. For example, MIMO communications use multiple antennas for communicating multiple data streams over a single radio frequency channel. MIMO communications benefit from higher signal to noise ratio, improved coding, and/or reduced signal interference due to spatial multiplexing differences of the radio environment. Switched diversity refers to communications in which a particular antenna is selected for operation at a particular time. For example, a switch can be used to select a particular antenna from a group of antennas based on a variety of factors, such as an observed bit error rate and/or a signal strength indicator. 
     The mobile device  800  can operate with beamforming in certain implementations. For example, the front end circuit  803  can include phase shifters having variable phase controlled by the transceiver  802 . Additionally, the phase shifters are controlled to provide beam formation and directivity for transmission and/or reception of signals using the antennas  804 . For example, in the context of signal transmission, the phases of the transmit signals provided to the antennas  804  are controlled such that radiated signals from the antennas  804  combine using constructive and destructive interference to generate an aggregate transmit signal exhibiting beam-like qualities with more signal strength propagating in a given direction. In the context of signal reception, the phases are controlled such that more signal energy is received when the signal is arriving to the antennas  804  from a particular direction. In certain implementations, the antennas  804  include one or more arrays of antenna elements to enhance beamforming. 
     The baseband system  801  is coupled to the user interface  807  to facilitate processing of various user input and output (I/O), such as voice and data. The baseband system  801  provides the transceiver  802  with digital representations of transmit signals, which the transceiver  802  processes to generate RF signals for transmission. The baseband system  801  also processes digital representations of received signals provided by the transceiver  802 . As shown in  FIG. 11 , the baseband system  801  is coupled to the memory  806  of facilitate operation of the mobile device  800 . 
     The memory  806  can be used for a wide variety of purposes, such as storing data and/or instructions to facilitate the operation of the mobile device  800  and/or to provide storage of user information. 
     The power management system  805  provides a number of power management functions of the mobile device  800 . In certain implementations, the power management system  805  includes a PA supply control circuit that controls the supply voltages of the power amplifiers  811 . For example, the power management system  805  can be configured to change the supply voltage(s) provided to one or more of the power amplifiers  811  to improve efficiency, such as power added efficiency (PAE). 
     As shown in  FIG. 11 , the power management system  805  receives a battery voltage from the battery  808 . The battery  808  can be any suitable battery for use in the mobile device  800 , including, for example, a lithium-ion battery. 
       FIG. 12A  is a schematic diagram of one embodiment of a packaged module  900 .  FIG. 12B  is a schematic diagram of a cross-section of the packaged module  900  of  FIG. 12A  taken along the lines  12 B- 12 B. 
     The packaged module  900  includes radio frequency components  901 , a semiconductor die  902 , surface mount devices  903 , wirebonds  908 , a package substrate  920 , and encapsulation structure  940 . The package substrate  920  includes pads  906  formed from conductors disposed therein. Additionally, the semiconductor die  902  includes pins or pads  904 , and the wirebonds  908  have been used to connect the pads  904  of the die  902  to the pads  906  of the package substrate  920 . 
     The packaged module  900  can be implemented to include one or more radio frequency processing circuits with tunable filters in accordance with the teachings herein. The radio frequency processing circuit can be implemented on the package substrate  920 , including using components of the die  902  and/or other components attached to the package substrate  920 . In certain implementations, the packaged module  900  corresponds to a front end module (FEM). 
     Although the packaged module  900  illustrates one example of a module implemented in accordance with the teachings herein, other implementations are possible. 
     As shown in  FIG. 12B , the packaged module  900  is shown to include a plurality of contact pads  932  disposed on the side of the packaged module  900  opposite the side used to mount the semiconductor die  902 . Configuring the packaged module  900  in this manner can aid in connecting the packaged module  900  to a circuit board, such as a phone board of a wireless device. The example contact pads  932  can be configured to provide radio frequency signals, bias signals, and/or power (for example, a power supply voltage and ground) to the semiconductor die  902 . As shown in  FIG. 12B , the electrical connections between the contact pads  932  and the semiconductor die  902  can be facilitated by connections  933  through the package substrate  920 . The connections  933  can represent electrical paths formed through the package substrate  920 , such as connections associated with vias and conductors of a multilayer laminated package substrate. 
     In some embodiments, the packaged module  900  can also include one or more packaging structures to, for example, provide protection and/or facilitate handling. Such a packaging structure can include overmold or encapsulation structure  940  formed over the packaging substrate  920  and the components and die(s) disposed thereon. 
     It will be understood that although the packaged module  900  is described in the context of electrical connections based on wirebonds, one or more features of the present disclosure can also be implemented in other packaging configurations, including, for example, flip-chip configurations. 
     Conclusion 
     Unless the context clearly requires otherwise, 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 word “coupled”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Likewise, the word “connected”, as generally used herein, refers 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. 
     Moreover, conditional language used herein, such as, among others, “can,” “could,” “might,” “can,” “e.g.,” “for example,” “such as” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment. 
     The above detailed description of embodiments of the invention 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 skilled in the relevant art will recognize. 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. Also, 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 system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments. 
     While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.