HK1219818B - Diversity receiver front end system with switching network - Google Patents

Description

Diversity receiver front-end system with switching network

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/073,043, filed on October 31, 2014, entitled “DIVERSITY RECEIVER FRONT END SYSTEM,” U.S. Provisional Application No. 62/073,041, filed on October 31, 2014, entitled “ADAPTIVE MULTIBAND LNA FOR CARRIER AGGREGATION,” U.S. Application No. 14/727,739, filed on June 1, 2015, entitled “DIVERSITY RECEIVER FRONT END SYSTEM WITH VARIABLE-GAIN AMPLIFIERS,” and U.S. Application No. 14/727,739, filed on June 9, 2015, entitled “DIVERSITY RECEIVER FRONT END SYSTEM WITH SWITCHING NETWORK," the disclosures of each of which are hereby expressly incorporated herein by reference in their entirety.

Technical Field

The present application relates generally to wireless communication systems having one or more diversity receive antennas.

Background Art

In wireless communication applications, size, cost, and performance are examples of factors that may be important for a given product. For example, to improve performance, wireless components such as diversity receive antennas and associated circuitry are becoming more popular.

In many radio frequency (RF) applications, the diversity receive antenna is placed physically away from the primary antenna. When both antennas are used simultaneously, the transceiver can process the signals from both antennas to increase data throughput.

Summary of the Invention

According to some embodiments, the present application relates to a receiving system comprising a plurality of amplifiers. Each of the plurality of amplifiers is disposed along a corresponding one of a plurality of paths between an input of the receiving system and an output of the receiving system and is configured to amplify a signal received at the amplifier. The receiving system further comprises a switching network comprising one or more single-pole, single-throw switches. Each of the switches couples two of the plurality of paths. The receiving system further comprises a controller configured to receive a band select signal and, based on the band select signal, enable one of the plurality of amplifiers and control the switching network.

In some embodiments, the controller may be configured to, in response to receiving a band selection signal indicating a single frequency band, enable one of the plurality of amplifiers corresponding to the single frequency band and control the switch network to open all of the one or more switches.

In some embodiments, the controller may be configured to, in response to receiving a band selection signal indicating a plurality of frequency bands, enable one of the plurality of amplifiers corresponding to one of the plurality of frequency bands, and control the switching network to turn on at least one of the one or more switches between paths corresponding to the plurality of frequency bands.

In some embodiments, the receiving system may further include a plurality of phase shift components, each of which may be disposed along a corresponding one of the plurality of paths and configured to phase shift a signal passing through the phase shift component to increase the impedance of a frequency band corresponding to another one of the plurality of paths. In some embodiments, each of the plurality of phase shift components may be disposed between the switching network and the input. In some embodiments, at least one of the plurality of phase shift components may include an adjustable phase shift component configured to phase shift the signal passing through the adjustable phase shift component by an amount controlled by a phase shift tuning signal received from a controller. In some embodiments, the controller may be configured to generate the phase shift tuning signal based on the frequency band selection signal.

In some embodiments, the receiving system may further include a plurality of impedance matching components. Each of the plurality of impedance matching components may be disposed along a corresponding one of the plurality of paths and may be configured to reduce a noise figure of the one of the plurality of paths. In some embodiments, each of the plurality of impedance matching components may be disposed between the switching network and a corresponding one of the plurality of amplifiers. In some embodiments, at least one of the plurality of impedance matching components may include an adjustable impedance matching component configured to present an impedance controlled by an impedance tuning signal received from the controller. In some embodiments, the controller may be configured to generate the impedance tuning signal based on the band select signal.

In some embodiments, the receiving system may further include a multiplexer configured to separate an input signal received at the input into a plurality of signals at a plurality of corresponding frequency bands propagating along the plurality of paths.

In some embodiments, at least one of the plurality of amplifiers may include a dual-stage amplifier.

In some embodiments, the controller may be further configured to enable one of the plurality of amplifiers and disable other amplifiers of the plurality of amplifiers.

In some embodiments, the present application relates to a radio frequency (RF) module comprising a packaging substrate configured to accommodate a plurality of components. The RF module further comprises a receiving system implemented on the packaging substrate. The receiving system comprises a plurality of amplifiers. Each of the plurality of amplifiers is arranged along a corresponding one of a plurality of paths between an input of the receiving system and an output of the receiving system, and is configured to amplify a signal received at the amplifier. The receiving system further comprises a switching network comprising one or more single-pole single-throw switches. Each of the switches couples two of the plurality of paths. The receiving system further comprises a controller configured to receive a band select signal and enable one of the plurality of amplifiers and control the switching network based on the band select signal.

In some embodiments, the RF module may be a diversity receiver front-end module (FEM).

In some embodiments, the receiving system may further include a plurality of phase shifting components. Each of the plurality of phase shifting components may be disposed along a corresponding one of the plurality of paths and may be configured to phase shift a signal passing through the phase shifting component to increase impedance in a frequency band corresponding to another one of the plurality of paths.

According to some teachings, the present application relates to a wireless device comprising a first antenna configured to receive a first radio frequency (RF) signal. The wireless device also comprises a first front-end module (FEM) in communication with the first antenna. The first FEM comprises a packaging substrate configured to house a plurality of components. The first FEM also comprises a receiving system implemented on the packaging substrate. The receiving system comprises a plurality of amplifiers. Each of the plurality of amplifiers is disposed along a corresponding one of a plurality of paths between an input of the receiving system and an output of the receiving system and is configured to amplify a signal received at the amplifier. The receiving system also comprises a switching network comprising one or more single-pole, single-throw switches. Each of the switches couples two of the plurality of paths. The receiving system also comprises a controller configured to receive a band select signal and, based on the band select signal, enable one of the plurality of amplifiers and control the switching network. The wireless device also comprises a transceiver configured to receive a processed version of the first RF signal from the output via a cable and generate data bits based on the processed version of the first RF signal.

In some embodiments, the wireless device may further include a second antenna configured to receive a second radio frequency (RF) signal and a second FEM in communication with the second antenna. The transceiver may be configured to receive a processed version of the second RF signal from an output of the second FEM and generate data bits based on the processed version of the second RF signal.

In some embodiments, the receiving system may further include a plurality of phase shifting components. Each of the plurality of phase shifting components may be disposed along a corresponding one of the plurality of paths and may be configured to phase shift a signal passing through the phase shifting component to increase impedance in a frequency band corresponding to another one of the plurality of paths.

For the purpose of summarizing this application, certain aspects, advantages and novel features of the present invention have been described herein. It should be understood that, according to any specific embodiment of the present invention, it is not necessary to achieve all of these advantages. Thus, the present invention may be implemented or realized in a manner that realizes or optimizes one or a group of advantages as taught herein, without realizing other advantages that may be taught or suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless device having a communication module coupled to a main antenna and a diversity antenna.

FIG2 shows a diversity receiver (DRx) configuration including a DRx front-end module (FEM).

3 illustrates that in some embodiments, a diversity receiver (DRx) configuration may include a DRx module having multiple paths corresponding to multiple frequency bands.

4 illustrates that in some embodiments, a diversity receiver configuration may include a diversity RF module having fewer amplifiers than a diversity receiver (DRx) module.

FIG5 illustrates that in some embodiments, a diversity receiver configuration may include a DRx module having a single-pole, single-throw switch.

FIG6 illustrates that in some embodiments, a diversity receiver configuration may include a DRx module with tunable phase shift components.

FIG7 shows one embodiment of a flow chart representation of a method of processing an RF signal.

FIG8 illustrates a module having one or more features described herein.

FIG9 illustrates a wireless device having one or more features described herein.

DETAILED DESCRIPTION

Subheadings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed invention.

1 shows a wireless device 100 having a communication module 110 coupled to a main antenna 130 and a diversity antenna 140. The communication module 110 (and its components) may be controlled by a controller 120. The communication module 110 includes a transceiver 112 configured to convert between analog radio frequency (RF) signals and digital data signals. To this end, the transceiver 112 may include a digital-to-analog converter, an analog-to-digital converter, a local oscillator for modulating or demodulating baseband analog signals to or from a carrier frequency, a baseband processor for converting between digital samples and data bits (e.g., voice or other types of data), or other components.

The communication module 110 also includes an RF module 114 coupled between the main antenna 130 and the transceiver 112. Because the RF module 114 can be physically close to the main antenna 130 to reduce attenuation due to cable loss, the RF module 114 can be referred to as a front-end module (FEM). The RF module 114 can perform processing on analog signals received from the main antenna 130 for use with the transceiver 112, or on analog signals received from the transceiver 112 for transmission via the main antenna 130. To this end, the RF module 114 may include filters, power amplifiers, band select switches, matching circuits, and other components. Similarly, the communication module 110 includes a diversity RF module 116 coupled between the diversity antenna 140 and the transceiver 112, which performs similar processing.

When a signal is transmitted to a wireless device, the signal may be received at both the main antenna 130 and the diversity antenna 140. The main antenna 130 and the diversity antenna 140 may be physically separated so that the signals received at the main antenna 130 and the diversity antenna 140 have different characteristics. For example, in one embodiment, the main antenna 130 and the diversity antenna 140 may receive signals with different attenuation, noise, frequency response, or phase shift. The transceiver 112 may use the two signals with different characteristics to determine the data bits corresponding to the signals. In some embodiments, the transceiver 112 selects between the main antenna 130 and the diversity antenna 140 based on the characteristics, for example, selecting the antenna with the highest signal-to-noise ratio. In some embodiments, the transceiver 112 combines the signals from the main antenna 130 and the diversity antenna 140 to improve the signal-to-noise ratio of the combined signal. In some embodiments, the transceiver 112 processes the signals to perform multiple-input/multiple-output (MIMO) communication.

Because the diversity antenna 140 is physically separated from the main antenna 130, the diversity antenna 140 is coupled to the communication module 110 via a transmission line 135, such as a cable or a printed circuit board (PCB) trace. In some embodiments, the transmission line 135 is lossy and attenuates the signal received at the diversity antenna 140 before it reaches the communication module 110. Therefore, in some embodiments, as described below, gain is applied to the signal received at the diversity antenna 140. Gain (as well as other analog processing, such as filtering) can be applied by a diversity receiver module. Because such a diversity receiver module can be located physically close to the diversity antenna 140, it can be referred to as a diversity receiver front-end module.

FIG2 illustrates a diversity receiver (DRx) configuration 200 including a DRx front-end module (FEM) 210. The DRx configuration 200 includes a diversity antenna 140 configured to receive a diversity signal and provide the diversity signal to the DRx FEM 210. The DRx FEM 210 is configured to process the diversity signal received from the diversity antenna 140. For example, the DRx FEM 210 may be configured to filter the diversity signal to one or more active frequency bands, e.g., as indicated by the controller 120. As another example, the DRx FEM 210 may be configured to amplify the diversity signal. To this end, the DRx FEM 210 may include filters, low-noise amplifiers, band select switches, matching circuits, and other components.

The DRx FEM 210 transmits the processed diversity signal via transmission line 135 to downstream modules, such as the diversity RF (D-RF) module 116, which feeds the further processed diversity signal to the transceiver 112. The diversity RF module 116 (and, in some embodiments, the transceiver) is controlled by a controller 120. In some embodiments, the controller 120 can be implemented within the transceiver 112.

FIG3 illustrates that, in some embodiments, a diversity receiver (DRx) configuration 300 may include a DRx module 310 having multiple paths corresponding to multiple frequency bands. The DRx configuration 300 includes a diversity antenna 140 configured to receive a diversity signal. In some embodiments, the diversity signal may be a single-band signal including data modulated onto a single frequency band. In some embodiments, the diversity signal may be a multi-band signal (also known as an inter-band carrier aggregation signal) including data modulated onto multiple frequency bands.

The DRx module 310 has an input for receiving a diversity signal from the diversity antenna 140 and an output for providing a processed diversity signal to the transceiver 330 (via the transmission line 135 and the diversity RF module 320). The input of the DRx module 310 is fed into the input of a first multiplexer 311. The first multiplexer (MUX) 311 includes a plurality of multiplexer outputs, each of which corresponds to a path between the input and output of the DRx module 310. Each path may correspond to a respective frequency band. The output of the DRx module 310 is provided by the output of a second multiplexer 312. The second multiplexer 312 includes a plurality of multiplexer inputs, each of which corresponds to one of the paths between the input and output of the DRx module 310.

The frequency bands may be cellular frequency bands such as UMTS (Universal Mobile Telecommunications System) frequency bands. For example, the first frequency band may be UMTS downlink or "Rx" frequency band 2 between 1930 megahertz (MHz) and 1990 MHz, and the second frequency band may be UMTS downlink or "Rx" frequency band 5 between 869 MHz and 894 MHz. Other downlink frequency bands may be used, such as those described below in Table 1 or other non-UMTS frequency bands.

In some embodiments, the DRx module 310 includes a DRx controller 302 that receives signals from the controller 120 (also referred to as a communication controller) and selectively activates one or more of the plurality of paths between the input and output based on the received signals. In some embodiments, the DRx module 310 does not include the DRx controller 302, and the controller 120 directly selectively activates one or more of the plurality of paths.

As described above, in some embodiments, the diversity signal is a single-band signal. Therefore, in some embodiments, the first multiplexer 311 is a single-pole, multiple-throw (SPMT) switch that routes the diversity signal to one of the multiple paths corresponding to the frequency band of the single-band signal based on a signal received from the DRx controller 302. The DRx controller 302 may generate a signal based on a band selection signal received by the DRx controller 302 from the communications controller 120. Similarly, in some embodiments, the second multiplexer 312 is an SPMT switch that routes the signal from one of the multiple paths corresponding to the frequency band of the single-band signal based on a signal received from the DRx controller 302.

As described above, in some embodiments, the diversity signal is a multi-band signal. Therefore, in some embodiments, the first multiplexer 311 is a signal separator that routes the diversity signal to two or more paths corresponding to two or more frequency bands of the multi-band signal from a plurality of paths based on a separator control signal received from the DRx controller 302. The function of the signal separator may be implemented as an SPMT switch, a diplexer filter, or some combination of these devices. Similarly, in some embodiments, the second multiplexer 312 is a signal combiner that combines signals from two or more paths corresponding to two or more frequency bands of the multi-band signal from a plurality of paths based on a combiner control signal received from the DRx controller 302. The function of the signal combiner may be implemented as an SPMT switch, a diplexer filter, or some combination of these devices. The DRx controller 302 may generate the separator control signal and the combiner control signal based on the band selection signal received by the DRx controller 302 from the communication controller 120.

Thus, in some embodiments, the DRx controller 302 is configured to selectively activate one or more of the plurality of paths based on a band selection signal received by the DRx controller 302 (e.g., from the communications controller 120). In some embodiments, the DRx controller 302 is configured to selectively activate one or more of the plurality of paths by sending a splitter control signal to the signal splitter and sending a combiner control signal to the signal combiner.

The DRx module 310 includes a plurality of bandpass filters 313a-313d. Each of the bandpass filters 313a-313d is disposed along a corresponding one of the plurality of paths and is configured to filter signals received at the bandpass filters to a corresponding frequency band of the one of the plurality of paths. In some embodiments, the bandpass filters 313a-313d are further configured to filter signals received at the bandpass filters to a downlink frequency sub-band of the corresponding frequency band of the one of the plurality of paths. The DRx module 310 includes a plurality of amplifiers 314a-314d. Each of the amplifiers 314a-314d is disposed along a corresponding one of the plurality of paths and is configured to amplify signals received at the amplifiers.

In some embodiments, amplifiers 314a-314d are narrowband amplifiers configured to amplify signals within the corresponding frequency band of the path in which they are located. In some embodiments, amplifiers 314a-314d may be controlled by the DRx controller 302. For example, in some embodiments, each of amplifiers 314a-314d includes an enable/disable input and is enabled (or disabled) based on an amplifier enable signal received at the enable/disable input. The amplifier enable signal may be sent by the DRx controller 302. Thus, in some embodiments, the DRx controller 302 is configured to selectively activate one or more of the multiple paths by sending an amplifier enable signal to one or more of the amplifiers 314a-314d, respectively, located along one or more of the multiple paths. In such embodiments, rather than being controlled by the DRx controller 302, the first multiplexer 311 may be a signal splitter that routes a diversity signal to each of the multiple paths, while the second multiplexer 312 may be a signal combiner that combines the signals from each of the multiple paths. However, in embodiments where the DRx controller 302 controls the first multiplexer 311 and the second multiplexer 312 , the DRx controller 302 may also enable (or disable) specific amplifiers 314 a - 314 d , for example, to conserve battery.

In some embodiments, the amplifiers 314a-314d are variable gain amplifiers (VGAs). Thus, in some embodiments, the DRx module 310 includes a plurality of variable gain amplifiers (VGAs), each VGA disposed along a corresponding one of the plurality of paths and configured to amplify a signal received at the VGA at a gain controlled by an amplifier control signal received from the DRx controller 302.

The gain of the VGA can be bypassable, step-variable, or continuously variable. In some embodiments, at least one of the VGAs includes a fixed-gain amplifier and a bypass switch controllable by an amplifier control signal. The bypass switch can (in a first position) connect the line between the input of the fixed-gain amplifier and the output of the fixed-gain amplifier, allowing the signal to bypass the fixed-gain amplifier. The bypass switch can (in a second position) disconnect the line between the input and output, allowing the signal to pass through the fixed-gain amplifier. In some embodiments, when the bypass switch is in the first position, the fixed-gain amplifier is disabled or otherwise reconfigured to accommodate the bypass mode.

In some embodiments, at least one of the VGAs includes a step-variable gain amplifier configured to amplify a signal received at the VGA with a gain of one of a plurality of configured amounts indicated by an amplifier control signal. In some embodiments, at least one of the VGAs includes a continuously-variable gain amplifier configured to amplify a signal received at the VGA with a gain proportional to the amplifier control signal.

In some embodiments, amplifiers 314a-314d are variable current amplifiers (VCAs). The current drawn by the VCAs can be bypassable, step-variable, or continuously variable. In some embodiments, at least one of the VCAs includes a fixed current amplifier and a bypass switch controllable by an amplifier control signal. The bypass switch can (in a first position) connect the line between the input of the fixed current amplifier and the output of the fixed current amplifier, bypassing the signal through the fixed current amplifier. The bypass switch can (in a second position) disconnect the line between the input and output, allowing the signal to pass through the fixed current amplifier. In some embodiments, when the bypass switch is in the first position, the fixed current amplifier is disabled or otherwise reconfigured to accommodate the bypass mode.

In some embodiments, at least one of the VCAs includes a step-variable current amplifier configured to amplify a signal received at the VCA by drawing one of a plurality of configured amounts of current indicated by an amplifier control signal. In some embodiments, at least one of the VCAs includes a continuously-variable current amplifier configured to amplify a signal received at the VCA by drawing a current proportional to the amplifier control signal.

In some embodiments, amplifiers 314a-314d are fixed gain, fixed current amplifiers. In some embodiments, amplifiers 314a-314d are fixed gain, variable current amplifiers. In some embodiments, amplifiers 314a-314d are variable gain, fixed current amplifiers. In some embodiments, amplifiers 314a-314d are variable gain, variable current amplifiers.

In some embodiments, the DRx controller 302 generates the amplifier control signal based on a quality of service metric of an input signal received at the input. In some embodiments, the DRx controller 302 generates the amplifier control signal based on a signal received from the communications controller 120, which in turn may be based on a quality of service (QoS) metric of the received signal. The QoS metric of the received signal may be based at least in part on a diversity signal received on the diversity antenna 140 (e.g., the input signal received at the input). The QoS metric of the received signal may also be based on a signal received on the primary antenna. In some embodiments, the DRx controller 302 generates the amplifier control signal based on the QoS metric of the diversity signal without receiving a signal from the communications controller 120.

In some implementations, the QoS metric includes signal strength. As another example, the QoS metric may include bit error rate, data throughput, transmission delay, or any other QoS metric.

As described above, the DRx module 310 has an input for receiving a diversity signal from the diversity antenna 140 and an output for providing a processed diversity signal to the transceiver 330 (via the transmission line 135 and the diversity RF module 320). The diversity RF module 320 receives the processed diversity signal via the transmission line 135 and performs further processing. In particular, the processed diversity signal is split or routed to one or more paths by the diversity RF multiplexer 321, where the split or routed signals are filtered by corresponding bandpass filters 323a-323d and amplified by corresponding amplifiers 324a-324d. The output of each amplifier 324a-324d is provided to the transceiver 330.

Diversity RF multiplexer 321 can be controlled by controller 120 (directly or via an on-chip diversity RF controller) to selectively activate one or more paths. Similarly, amplifiers 324a-324d can be controlled by controller 120. For example, in some embodiments, each of amplifiers 324a-324d includes an enable/disable input and is enabled (or disabled) based on an amplifier enable signal. In some embodiments, amplifiers 324a-324d are variable gain amplifiers (VGAs) that amplify a signal received at the VGA at a gain controlled by an amplifier control signal received from controller 120 (or an on-chip diversity RF controller controlled by controller 120). In some embodiments, amplifiers 324a-324d are variable current amplifiers (VCAs).

Since the DRx module 310 added to the receiver chain already includes the diversity RF module 320, the number of bandpass filters in the DRx configuration 300 is doubled. Therefore, in some embodiments, the bandpass filters 323a-323d are not included in the diversity RF module 320. Instead, the bandpass filters 313a-313d of the DRx module 310 are used to reduce the strength of out-of-band blockers. In addition, the automatic gain control (AGC) table of the diversity RF module 320 can be shifted to reduce the amount of gain provided by the amplifiers 324a-324d of the diversity RF module 320 by the amount of gain provided by the amplifiers 314a-314d of the DRx module 310.

For example, if the DRx module gain is 15dB and the receiver sensitivity is -100dBm, then the diversity RF module 320 will see a sensitivity of -85dBm. If the closed-loop AGC of the diversity RF module 320 is active, its gain will automatically decrease by 15dB. However, both the signal component and the out-of-band blocker component are received and amplified by 15dB. Therefore, the 15dB gain reduction of the diversity RF module 320 may also be accompanied by a 15dB improvement in its linearity. In particular, the amplifiers 324a-324d of the diversity RF module 320 may be designed so that the linearity of the amplifiers increases as the gain decreases (or the current increases).

In some embodiments, the controller 120 controls the gain (and/or current) of the amplifiers 314a-314d of the DRx module 310 and the amplifiers 324a-324d of the diversity RF module 320. As in the example described above, the controller 120 can decrease the amount of gain provided by the amplifiers 324a-324d of the diversity RF module 320 in response to increasing the amount of gain provided by the amplifiers 314a-314d of the DRx module 310. Thus, in some embodiments, the controller 120 is configured to generate downstream amplifier control signals (for the amplifiers 324a-324d of the diversity RF module 320) based on the amplifier control signals (for the amplifiers 314a-314d of the DRx module 310) to control the gain of one or more downstream amplifiers 324a-324d coupled to the output (of the DRx module 310) via the transmission line 135. In some embodiments, the controller 120 also controls the gain of other components of the wireless device, such as amplifiers in a front-end module (FEM), based on the amplifier control signal.

As described above, in some embodiments, the bandpass filters 323a-323d are not included. Thus, in some embodiments, at least one of the downstream amplifiers 324a-324d is coupled to the output (of the DRx module 310) via the transmission line 135 without passing through the downstream bandpass filter.

FIG4 illustrates that, in some embodiments, a diversity receiver configuration 400 can include a diversity RF module 420 having fewer amplifiers than the diversity receiver (DRx) module 310. The diversity receiver configuration 400 includes the diversity antenna 140 and the DRx module 310, as described above with respect to FIG3. The output of the DRx module 310 is passed via the transmission line 135 to the diversity RF module 420, which differs from the diversity RF module 320 in FIG3 in that the diversity RF module 420 in FIG4 includes fewer amplifiers than the DRx module 310.

As described above, in some embodiments, the diversity RF module 420 does not include a bandpass filter. Therefore, in some embodiments, the one or more amplifiers 424 of the diversity RF module 420 need not be band-specific. Specifically, the diversity RF module 420 may include one or more paths, each including an amplifier 424, that are not mapped one-to-one with the paths of the DRx module 310. Such mapping of paths (or corresponding amplifiers) may be stored in the controller 120.

Thus, while the DRx module 310 includes multiple paths, each path corresponding to a frequency band, the diversity RF module 420 may include one or more paths that do not correspond to a single frequency band.

In some embodiments (as shown in FIG4 ), diversity RF module 420 includes a single broadband amplifier 424 that amplifies the signal received from transmission line 135 and outputs the amplified signal to multiplexer 421. Multiplexer 421 includes multiple multiplexer outputs, each corresponding to a respective frequency band. In some embodiments, diversity RF module 420 does not include any amplifiers.

In some embodiments, the diversity signal is a single-band signal. Therefore, in some embodiments, multiplexer 421 is an SPMT switch that routes the diversity signal to one of the multiple outputs corresponding to the frequency band of the single-band signal based on a signal received from controller 120. In some embodiments, the diversity signal is a multi-band signal. Therefore, in some embodiments, multiplexer 421 is a signal splitter that routes the diversity signal to two or more of the multiple outputs corresponding to two or more frequency bands of the multi-band signal based on a splitter control signal received from controller 120. In some embodiments, diversity RF module 420 may be combined with transceiver 330 into a single module.

In some embodiments, the diversity RF module 420 includes multiple amplifiers, each corresponding to a set of frequency bands. The signal from the transmission line 135 can be fed into a band splitter, which outputs high frequencies along a first path to a high-frequency amplifier and low frequencies along a second path to a low-frequency amplifier. The output of each amplifier can be provided to a multiplexer 421, which is configured to route the signal to a corresponding input of the transceiver 330.

FIG5 shows that in some embodiments, a diversity receiver configuration 500 may include a DRx module 510 having a single-pole, single-throw switch 519. The DRx module 510 includes two paths from an input of the DRx module 510 (which is coupled to the antenna 140) to an output of the DRx module 510 (which is coupled to the transmission line 135). The DRx module 510 includes a plurality of amplifiers 514a-514b, each of which is arranged along a corresponding one of the plurality of paths and configured to amplify a signal received at the amplifier. In some embodiments, as shown in FIG5, at least one of the plurality of amplifiers includes a dual-stage amplifier.

In the DRx module 510 of FIG5 , the signal separator and bandpass filter are implemented as a duplexer 511. The duplexer 511 includes an input coupled to the antenna 140, a first output coupled to a phase shift component 527a disposed along a first path, and a second output coupled to a second phase shift component 527b disposed along a second path. At the first output, the duplexer 511 outputs a signal received at the input (e.g., from the antenna 140) filtered to a first frequency band. At the second output, the duplexer 511 outputs a signal received at the input filtered to a second frequency band. In some embodiments, the duplexer 511 can be replaced with a triplexer, a quadplexer, or any other multiplexer configured to separate an input signal received at the input of the DRx module 510 into multiple signals propagating along multiple paths in corresponding multiple frequency bands.

In some embodiments, an output multiplexer or other signal combiner provided at the output of a DRx module, such as the second multiplexer 312 in FIG. 3 , may degrade the performance of the DRx module when receiving a single-band signal. For example, the output multiplexer may attenuate the single-band signal or introduce noise into the single-band signal. In some embodiments, when multiple amplifiers, such as amplifiers 314 a - 314 d in FIG. 3 , are simultaneously enabled to support multi-band signals, each amplifier may introduce not only in-band noise but also out-of-band noise for each of the other multiple bands.

The DRx module 510 of Figure 5 addresses some of these issues. The DRx module 510 includes a single-pole single-throw (SPST) switch 519 that couples the first path to the second path. To operate in single-band mode for the first frequency band, the switch 519 is placed in the open position, the first amplifier 514a is enabled, and the second amplifier 514b is disabled. Thus, the single-band signal at the first frequency band propagates from the antenna 140 to the transmission line 135 along the first path without switching losses. Similarly, to operate in single-band mode for the second frequency band, the switch 519 is placed in the open position, the first amplifier 514a is disabled, and the second amplifier 514b is enabled. Thus, the single-band signal at the second frequency band propagates from the antenna 140 to the transmission line 135 along the second path without switching losses.

To operate in multi-band mode for both the first and second frequency bands, the switch 519 is placed in the on position, the first amplifier 514a is enabled, and the second amplifier 514b is disabled. Thus, the first frequency band portion of the multi-band signal propagates along a first path through the first phase shift component 527a, the first impedance matching component 526a, and the first amplifier 514a. The first frequency band portion is prevented from traversing the switch 519 and propagates in the opposite direction along a second path through the second phase shift component 527b. Specifically, the second phase shift component 527b is configured to phase shift the first frequency band portion of the signal passed through the second phase shift component 527b to maximize (or at least increase) the impedance at the first frequency band.

The second frequency band portion of the multi-band signal propagates along the second path through the second phase shift component 527b, traverses the switch 519, and propagates along the first path through the first impedance matching component 526a and the first amplifier 514a. The second frequency band portion is prevented from propagating in the opposite direction along the first path by the first phase shift component 527a. In particular, the first phase shift component 527a is configured to phase shift the second frequency band portion of the signal transmitted through the first phase shift component 527a to maximize (or at least increase) the impedance at the second frequency band.

Each path can be characterized by a noise figure and a gain. The noise figure of each path is a representation of the degradation of the signal-to-noise ratio (SNR) caused by the amplifiers and impedance matching components 526a-526b disposed along the path. Specifically, the noise figure of each path is the decibel (dB) difference between the SNR at the input of the impedance matching components 526a-526b and the SNR at the output of the amplifiers 314a-314b. Therefore, the noise figure is a measure of the difference between the noise output of an amplifier and the noise output of an "ideal" amplifier with the same gain (which produces no noise).

The noise figure of each path can be different for different frequency bands. For example, a first path can have a first noise figure for a first frequency band and a second noise figure for a second frequency band. The noise figure and gain of each path (at each frequency band) can depend at least in part on the impedance (at each frequency band) of the impedance matching components 526a-526b. Therefore, it would be advantageous if the impedance of the impedance matching components 526a-526b minimizes (or reduces) the noise figure of each path.

In some embodiments, the second impedance matching component 526b presents an impedance that minimizes (or reduces) the noise figure of the second frequency band. In some embodiments, the first impedance matching component 526a minimizes (or reduces) the noise figure of the first frequency band. In some embodiments, because the second frequency band portion of the multi-band signal can partially propagate along the first portion, the first impedance matching component 526a minimizes (or reduces) a metric including the noise figure of the first frequency band and the noise figure of the second frequency band.

The impedance matching components 526a-526b can be implemented as passive circuits. In particular, the impedance matching components 526a-526b can be implemented as RLC circuits and include one or more passive components, such as resistors, inductors, and/or capacitors. The passive components can be connected in parallel and/or in series and can be connected between the output of the phase shift components 527a-527b and the input of the amplifiers 514a-514b or between the output of the phase shift components 527a-527b and a ground voltage.

Similarly, the phase shift components 527a-527b can be implemented as passive circuits. In particular, the phase shift components 527a-527b can be implemented as LC circuits and include one or more passive components, such as inductors and/or capacitors. The passive components can be connected in parallel and/or in series and can be connected between the output of the duplexer 511 and the input of the impedance matching components 526a-526b or between the output of the duplexer 511 and the ground voltage.

6 shows that in some embodiments, a diversity receiver configuration 600 may include a DRx module 610 having adjustable phase shift components 627a-627d. Each of the adjustable phase shift components 627a-627d may be configured to shift the phase of a signal passing through the adjustable phase shift component by an amount controlled by a phase shift tuning signal received from a controller.

The diversity reception configuration 600 includes a DRx module 610 having an input coupled to the antenna 140 and an output coupled to the transmission line 135. The DRx module 610 includes multiple paths between the input and output of the DRx module 610. Each path includes a multiplexer 311, a bandpass filter 313a-313d, an adjustable phase shift component 627a-627d, a switch network 612, an adjustable impedance matching component 626a-626d, and an amplifier 314a-314d. As described above, the amplifiers 314a-314d can be variable gain amplifiers and/or variable current amplifiers.

Adjustable phase shift components 627a-627d may include one or more variable components, such as inductors and capacitors. The variable components may be connected in parallel and/or in series and may be connected between the output of multiplexer 311 and the input of switch network 612, or may be connected between the output of the multiplexer and ground.

The adjustable impedance matching components 626a-626d can be adjustable T circuits, adjustable PI circuits or any other adjustable matching circuits. The adjustable impedance matching components 626a-626d can include one or more variable components, such as resistors, inductors and capacitors. The variable components can be connected in parallel and/or in series and can be connected between the output of the switching network 612 and the input of the amplifiers 314a-314d, or can be connected between the output of the switching network 612 and the ground voltage.

The DRx controller 602 is configured to selectively activate one or more of the plurality of paths between an input and an output. In some embodiments, the DRx controller 602 is configured to selectively activate one or more of the plurality of paths based on a band select signal received by the DRx controller 602 (e.g., from a communications controller). The DRx controller 602 can selectively activate a path by, for example, enabling or disabling amplifiers 314a-314d, controlling the multiplexer 311 and/or the switch network 612, or through other mechanisms.

In some embodiments, the DRx controller 602 controls the switch network 612 based on a band select signal. The switch network includes a plurality of SPST switches, each of which couples two of the plurality of paths. The DRx controller 602 may send a switch signal (or multiple switch signals) to the switch network to open or close the plurality of SPST switches. For example, if the band select signal indicates that the input signal includes a first frequency band and a second frequency band, the DRx controller 602 may close the switch between the first path and the second path. If the band select signal indicates that the input signal includes a second frequency band and a fourth frequency band, the DRx controller 602 may close the switch between the second path and the fourth path. If the band select signal indicates that the input signal includes the first frequency band, the second frequency band, and the fourth frequency band, the DRx controller 602 may close both switches (and/or close the switch between the first path and the second path and the switch between the first path and the fourth path). If the band selection signal indicates that the input signal includes a second frequency band, a third frequency band, and a fourth frequency band, the DRx controller 602 may turn on the switch between the second path and the third path and the switch between the third path and the fourth path (and/or turn on the switch between the second path and the third path and the switch between the second path and the fourth path).

In some embodiments, the DRx controller 602 is configured to tune the adjustable phase shift components 627a-627d. In some embodiments, the DRx controller 602 tunes the adjustable phase shift components 627a-627d based on a band select signal. For example, the DRx controller 602 may tune the adjustable phase shift components 627a-627d based on a lookup table that associates a frequency band (or set of frequency bands) indicated by the band select signal with a tuning parameter. Thus, in response to the band select signal, the DRx controller 602 may send a phase shift tuning signal to the adjustable phase shift components 627a-627d in each active path to tune the adjustable phase shift components (or their variable components) according to the tuning parameter.

The DRx controller 602 can be configured to tune the adjustable phase shift components 627a-627d in each active path to maximize (or at least increase) the impedance at the frequency band corresponding to the other active paths. Thus, if the first and third paths are active, the DRx controller 602 can tune the first phase shift component 627a to maximize (or at least increase) the impedance at the third frequency band, and if the first and fourth paths are active, the DRx controller 602 can tune the first phase shift component 627a to maximize (or at least increase) the impedance at the fourth frequency band.

In some embodiments, the DRx controller 602 is configured to tune the adjustable impedance matching components 626a-626d. In some embodiments, the DRx controller 602 tunes the adjustable impedance matching components 626a-626d based on a band select signal. For example, the DRx controller 602 can tune the adjustable impedance matching components 626a-626d based on a lookup table that associates a frequency band (or set of frequency bands) indicated by the band select signal with tuning parameters. Thus, in response to the band select signal, the DRx controller 602 can send an impedance tuning signal to the adjustable impedance matching components 626a-626d in the path with the activated amplifier according to the tuning parameters.

In some implementations, the DRx controller 602 tunes the adjustable impedance matching components 626a - 626d in paths having active amplifiers to minimize (or reduce) metrics including noise figure for the corresponding frequency band of each active path.

In various implementations, one or more of the adjustable phase shift components 627 a - 627 d or the adjustable impedance matching components 626 a - 626 d may be replaced by fixed components that are not controlled by the DRx controller 602 .

FIG7 illustrates one embodiment of a flow diagram of a method 700 for processing an RF signal. In some embodiments (and as described in detail below as an example), the method 700 is performed by a controller, such as the Drx controller 602 of FIG6 . In some embodiments, the method 700 is performed by processing logic comprising hardware, firmware, software, or a combination thereof. In some embodiments, the method 700 is performed by a processor executing code stored in a non-transitory computer-readable medium (e.g., a memory). Briefly, the method 700 includes receiving a band select signal and routing the received RF signal along one or more paths to process the received RF signal.

Method 700 begins at block 710 when a controller receives a band selection signal. The controller may receive the band selection signal from another controller, or from a cellular base station or other external source. The band selection signal may indicate one or more frequency bands in which the wireless device transmits and receives RF signals. In some embodiments, the band selection signal indicates a set of frequency bands to be used for carrier aggregation communications.

At block 720, the controller sends an amplifier enable signal to an amplifier of the DRx module based on the band select signal. In some embodiments, the band select signal indicates a single frequency band, and the controller sends the amplifier enable signal to enable an amplifier located along a path corresponding to the single frequency band. The controller may send the amplifier enable signal to disable other amplifiers located along other paths corresponding to other frequency bands. In some embodiments, the band select signal indicates multiple frequency bands, and the controller sends the amplifier enable signal to enable an amplifier located along one of the multiple paths corresponding to one of the multiple frequency bands. The controller may send the amplifier enable signal to disable other amplifiers. In some embodiments, the controller enables an amplifier located along a path corresponding to the lowest frequency band.

At block 730, the controller sends a switching signal based on the band select signal to control a switching network of single-pole, single-throw (SPST) switches. The switching network includes a plurality of SPST switches coupled to a plurality of paths corresponding to a plurality of frequency bands. In some embodiments, the band select signal indicates a single frequency band, and the controller sends a switching signal to turn off all of the SPST switches. In some embodiments, the band select signal indicates a plurality of frequency bands, and the controller sends a switching signal to turn on one or more of the SPST switches, thereby coupling the paths corresponding to the plurality of frequency bands.

At block 740, the controller sends a tuning signal to one or more adjustable components based on the band select signal. The adjustable components may include one or more of a plurality of adjustable phase shift components or a plurality of adjustable impedance matching components. The controller may tune the adjustable components based on a lookup table that associates a frequency band (or set of frequency bands) indicated by the band select signal with a tuning parameter. Thus, in response to the band select signal, the DRx controller may send a tuning signal to the adjustable component (of the activated path) to tune the adjustable component (or its variable component) according to the tuning parameter.

FIG8 illustrates that in some embodiments, some or all diversity receiver configurations (e.g., those shown in FIG3 , 4 , 5 , and 6 ) can be implemented in whole or in part within a module. Such a module can be, for example, a front-end module (FEM). Such a module can be, for example, a diversity receiver (DRx) FEM. In the example of FIG8 , module 800 can include a package substrate 802 , and various components can be mounted on such package substrate 802 . For example, a controller 804 (which can include a front-end power management integrated circuit (FE-PIMC)), a low-noise amplifier assembly 806 (which can include one or more variable gain amplifiers), a matching component 808 (which can include one or more fixed or adjustable phase shift components 831 and one or more fixed or adjustable impedance matching components 832), a multiplexer assembly 810 (which can include a switching network 833 of SPST switches), and a filter bank 812 (which can include one or more bandpass filters) can be mounted and/or implemented on and/or within the package substrate 802 . Other components, such as a plurality of SMT devices 814, can also be mounted on the package substrate 802 . While all of the various components are shown as being laid out on the package substrate 802 , it will be understood that certain component(s) may be implemented over certain other component(s).

In some embodiments, devices and/or circuits having one or more features described herein may be included in an RF electronic device, such as a wireless device. Such devices and/or circuits may be implemented directly in the wireless device, in a modular form as described herein, or in some combination thereof. In some embodiments, such a wireless device may include, for example, a cellular phone, a smartphone, a handheld wireless device with or without telephone functionality, a wireless tablet, and the like.

9 illustrates an example wireless device 900 having one or more advantageous features described herein. In the context of one or more modules having one or more features described herein, such modules may be generally represented by dashed box 901 (which may be implemented as, for example, a front-end module), diversity RF module 911 (which may be implemented as, for example, a downstream module), and diversity receiver (DRx) module 800 (which may be implemented as, for example, a front-end module).

9 , a power amplifier (PA) 920 may receive its corresponding RF signal from a transceiver 910, which may be configured and operated in a known manner to generate RF signals to be amplified and transmitted, and to process received signals. The transceiver 910 is shown interacting with a baseband subsystem 908, which is configured to provide conversion between data and/or voice signals for a user and RF signals for the transceiver 910. The transceiver 910 may also communicate with a power management component 906, which is configured to manage power for the operation of the wireless device 900. Such power management may also control the operation of the baseband subsystem 908 and modules 901, 911, and 800.

The baseband subsystem 908 is shown connected to the user interface 902 to facilitate various inputs and outputs of voice and/or data to and from the user. The baseband subsystem 908 may also be connected to the memory 904, which is configured to store data and/or instructions to facilitate the operation of the wireless device and/or provide storage of user information.

In the example wireless device 900, the output of the PA 920 is shown matched (via a corresponding matching circuit 922) and routed to its corresponding duplexer 924. The amplified and filtered signal can then be routed to the primary antenna 916 via the antenna switch 914 for transmission. In some embodiments, the duplexer 924 can allow simultaneous transmit and receive operations using a common antenna (e.g., the primary antenna 916). In FIG9, the receive signal is shown routed to the "Rx" path, which can include, for example, a low noise amplifier (LNA).

The wireless device also includes a diversity antenna 926 and a diversity receiver module 800 that receives signals from the diversity antenna 926. The diversity receiver module 800 processes the received signals and sends the processed signals via a cable 935 to a diversity RF module 911, which further processes the signals before feeding them to the transceiver 910.

One or more features of the present application may be implemented with the various cellular frequency bands described herein. Examples of such frequency bands are listed in Table 1. It will be understood that at least some frequency bands may be divided into sub-bands. It will also be understood that one or more features of the present application may be implemented with frequency ranges that do not have a designation such as the examples in Table 1.

Table 1

Unless the context clearly requires otherwise, throughout the specification and claims, the terms "comprise," "comprising," and the like are to be interpreted in an inclusive sense, as opposed to an exclusive or exhaustive sense, that is, in the sense of "including but not limited to." The word "coupled," as generally used herein, means that two or more elements can be connected directly or via one or more intermediate elements. Similarly, the term "connected," as generally used herein, means that two or more elements can be connected directly or via one or more intermediate elements. In addition, when used in this application, the terms "herein," "above," "below," and terms of similar meaning should refer to this application as a whole and not to any specific parts of this application. Where the context permits, terms in the above detailed description that use the singular or plural may also include the plural or singular, respectively. The term "or" when referring to a list of two or more items encompasses all of the following interpretations of the term: any item in the list, all items in the list, and any combination of items in the list.

Furthermore, unless otherwise specifically stated or understood in the context of use, conditional language used herein, such as, among others, "may," "could," "would," "might," "for example," "for example," "such as," etc., is generally intended to indicate that some embodiments include, while other embodiments do not include, certain features, elements, and/or conditions. Thus, such conditional language is generally not intended to imply that features, elements, and/or conditions are in any way required for one or more embodiments, or to imply that one or more embodiments must include logic for determining, with or without designer input or prompting, whether such features, elements, and/or characteristics are included or will be implemented in any particular embodiment.

The above detailed description of the embodiment of the present invention is not intended to be exhaustive or to limit the present invention to the precise form disclosed above. Although specific embodiments of the present invention and examples for the present invention have been described above for illustrative purposes, various equivalent modifications within the scope of the present invention are possible as will be appreciated by those skilled in the art. For example, although processes or blocks are presented in a given order, alternative embodiments may perform processes with steps in a different order, or employ systems with blocks in a different order, and some processes or blocks may be deleted, moved, added, subtracted, combined, and/or modified. Each of these processes or blocks may be implemented in a variety of ways. Similarly, although processes or blocks are sometimes shown as being performed serially, on the contrary, these processes or blocks may also 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.

Although certain embodiments of the present invention have been described, these embodiments have been presented by way of example only and are not intended to limit the scope of the present disclosure. Indeed, the novel methods and systems described herein may be implemented 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 present application. The accompanying drawings and their equivalents are intended to encompass such forms or modifications as would fall within the scope and spirit of the present application.

Claims (20)

1. A receiving system, comprising: A first amplifier is disposed along a first path between the input and the output of the receiving system and is configured to amplify the signal received at the first amplifier; A second amplifier is disposed along a second path between the input and the output of the receiving system, and is configured to amplify the signal received at the second amplifier. A single-pole single-throw switch, disposed between the first path and the second path, and configured to couple the first path and the second path; and A controller configured to receive a band selection signal and, based on the band selection signal, enable one of the first amplifier or the second amplifier and control the single-pole single-throw switch. 2. The receiving system of claim 1, wherein the controller is configured to, in response to receiving a band selection signal indicating a single frequency band, enable one of the first amplifiers or the second amplifier corresponding to the single frequency band, and disconnect the single-pole single-throw switch. 3. The receiving system of claim 1, wherein the controller is configured to, in response to receiving a band selection signal indicating a plurality of frequency bands, enable one of the first amplifiers or the second amplifiers corresponding to one of the plurality of frequency bands, and turn on the single-pole single-throw switch. 4. The receiving system of claim 1 further includes a first phase shifter disposed along the first path and configured to phase shift the signal transmitted through the first phase shifter to increase the impedance of the frequency band corresponding to the second path. 5. The receiving system of claim 4, wherein the first phase shifting component is disposed between the single-pole single-throw switch and the input of the receiving system. 6. The receiving system of claim 4, wherein the first phase shifting component includes an adjustable phase shifting component configured to phase shift a signal transmitted through the adjustable phase shifting component by an amount controlled by a phase shift tuning signal received from the controller. 7. The receiving system of claim 6, wherein the controller is configured to generate the phase-shift tuning signal based on the band selection signal. 8. The receiving system of claim 1, further comprising: a first impedance matching component disposed along the first path and configured to reduce the noise figure of the first path. 9. The receiving system of claim 8, wherein the first impedance matching component is disposed between the single-pole single-throw switch and the first amplifier. 10. The receiving system of claim 8, wherein the first impedance matching component includes an adjustable impedance matching component configured to present an impedance controlled by an impedance tuning signal received from the controller. 11. The receiving system of claim 7, wherein the controller is configured to generate the impedance tuning signal based on the band selection signal. 12. The receiving system of claim 1, further comprising: a multiplexer configured to separate an input signal received at an input of the receiving system into a first signal at a first frequency band propagating along the first path and a second signal at a second frequency band propagating along the second path. 13. The receiving system of claim 1, wherein at least one of the first amplifier or the second amplifier comprises a dual-stage amplifier. 14. The receiving system of claim 1, wherein the controller is further configured to disable the first amplifier or another amplifier of the second amplifier. 15. A radio frequency module, comprising: Packaging substrate, configured to accommodate multiple components; and A receiving system, implemented on the package substrate, includes a first amplifier, a second amplifier, a single-pole single-throw switch, and a controller. The first amplifier is disposed along a first path between the input and output of the RF module and configured to amplify a signal received at the first amplifier. The second amplifier is disposed along a second path between the input and output of the RF module and configured to amplify a signal received at the second amplifier. The single-pole single-throw switch is disposed between the first path and the second path and configured to couple the first path and the second path. The controller is configured to receive a band selection signal and enable one of the first amplifier or the second amplifier and control the switch based on the band selection signal. 16. The radio frequency module of claim 15, wherein the radio frequency module is a diversity receiver front-end module. 17. The radio frequency module of claim 15, wherein the receiving system further includes a first phase shifter disposed along the first path and configured to phase shift the signal transmitted through the first phase shifter to increase the impedance of the frequency band corresponding to the second path. 18. A wireless device, comprising: The first antenna is configured to receive a first radio frequency signal; A first front-end module, communicating with a first antenna, includes a packaging substrate configured to accommodate multiple components. The first front-end module also includes a receiving system implemented on the packaging substrate, the receiving system including a first amplifier, a second amplifier, a single-pole single-throw switch, and a controller. The first amplifier is disposed along a first path between the input and output of the front-end module and configured to amplify a signal received at the first amplifier. The second amplifier is disposed along a second path between the input and output of the front-end module and configured to amplify a signal received at the second amplifier. The single-pole single-throw switch is disposed between the first path and the second path and configured to couple the first path and the second path. The controller is configured to receive a band selection signal and, based on the band selection signal, enable one of the first amplifier or the second amplifier and control the switch. A transceiver configured to receive a processed version of the first radio frequency signal from the output via a cable and to generate data bits based on the processed version of the first radio frequency signal. 19. The wireless device of claim 18, further comprising: a second antenna configured to receive a second radio frequency signal and a second front-end module communicating with the second antenna, the transceiver being configured to receive a processed version of the second radio frequency signal from the output of the second front-end module and generate data bits based on the processed version of the second radio frequency signal. 20. The wireless device of claim 18, wherein the receiving system further includes a first phase-shifting component disposed along the first path and configured to phase-shift a signal transmitted through the first phase-shifting component to increase the impedance of a frequency band corresponding to the second path.