Radio frequency signal combiner and method of operating same

Abstract

To provide a switchable bidirectional radio frequency coupler.SOLUTION: A bidirectional coupler 300 includes input ports CPL_IN, CPL_ANT, output ports CPL_FL, CPL_FH, CPL_R, a main transmission line 302 coupled between the input ports and the output ports, and a coupled transmission line to be electromagnetically coupled to the main transmission line. The coupled transmission line includes a first segment 304a, a second segment 304b, and a switch 306 for coupling the first segment and the second segment during a first operation mode, and decoupling the first transmission line and the second transmission line during a second operation mode. This radio frequency coupling can be used in a front end modules of a communication device such as a mobile phone.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 63 / 152,409, entitled "Smart Bidirectional Coupler with Switchable Inductors," filed February 23, 2021, which is incorporated herein by reference in its entirety for all purposes.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates generally to bidirectional couplers. More particularly, aspects of the disclosure relate to systems and methods for improving coupler performance using switchable inductors. Summary of the Invention

[0003] According to an aspect of the present disclosure, there is provided a radio frequency signal coupler including an input port, an output port, a main transmission line coupled between the input port and the output port, and a coupled transmission line electromagnetically coupled to the main transmission line, the coupled transmission line including a first transmission line, a second transmission line, and a switch configured to couple the first transmission line to the second transmission line during a first mode of operation and to decouple the first transmission line to the second transmission line during a second mode of operation.

[0004] According to one embodiment, the switch is configured to couple the first transmission line and the second transmission line during a first mode of operation to provide a first coupling coefficient, and to decouple the first transmission line and the second transmission line during a second mode of operation to provide a second coupling coefficient.

[0005] According to another embodiment, the first operating mode corresponds to a first frequency range and the second operating mode corresponds to a second frequency range, the second frequency range being different from the first frequency range.

[0006] According to one example, the first coupling coefficient over the first frequency range is substantially similar to the second coupling coefficient over the second frequency range.

[0007] According to another example, the radio frequency coupler operates in the first and second operating modes to maintain a substantially constant insertion loss between the input and output ports over the first and second frequency ranges.

[0008] According to a further example, the radio frequency signal coupler is configured as a bidirectional coupler, with the input port and the output port each configured to receive an input radio frequency signal and to provide an output radio frequency signal.

[0009] According to a further embodiment, the radio frequency signal coupler further includes at least one forward output port and a reverse output port, and the coupled transmission line is coupled between the at least one forward output port and the reverse output port.

[0010] According to one example, at least one forward output port is configured to provide a forward coupled signal when an input radio frequency signal is received at the input port.

[0011] According to another example, the radio frequency signal coupler operates in the first and second modes of operation to maintain a power level of the forward coupled signal substantially constant across the first and second frequency ranges.

[0012] According to a further example, the reverse output port is configured to provide a reverse coupled signal when an input radio frequency signal is received at the output port.

[0013] According to another example, the radio frequency signal coupler operates in the first and second modes of operation to maintain a power level of the backward coupled signal substantially constant across the first and second frequency ranges.

[0014] According to another embodiment, at least one of the forward output port and the reverse output port are selectively coupled to a common output port.

[0015] According to some examples, at least one of the forward output port and the reverse port is selectively coupled to an adjustable termination circuit, and according to these examples, the impedance value provided by the adjustable termination circuit is adjusted based on the frequency of the input radio frequency signal.

[0016] According to another embodiment, the coupled transmission line includes a third transmission line, and the switch is configured to couple the third transmission line to the first transmission line and / or the second transmission line during a third mode of operation corresponding to a third frequency range, the third frequency range being different from the first frequency range and the second frequency range. According to a further embodiment, the switch is configured to couple the third transmission line to the first transmission line and / or the second transmission line during the third mode of operation to provide a third coupling coefficient.

[0017] According to another aspect of the present disclosure, there is provided a method of operating a radio frequency signal coupler, the method including receiving a radio frequency signal at one of an input port and an output port, providing the radio frequency signal to a main transmission line coupled between the input port and the output port, electromagnetically coupling a portion of the radio frequency signal to a coupled transmission line, the coupled transmission line including a first transmission line and a second transmission line, and operating a switch to couple the first transmission line to the second transmission line during a first mode of operation and to decouple the first transmission line to the second transmission line during a second mode of operation.

[0018] According to one embodiment, operating the switch to couple the first transmission line and the second transmission line during the first mode of operation further includes providing a first coupling coefficient during the first mode of operation.

[0019] According to one example, the first coupling coefficient corresponds to a first frequency range.

[0020] According to one embodiment, operating the switch to decouple the first and second transmission lines during the second mode of operation further includes providing a second coupling coefficient during the second mode of operation.

[0021] According to one example, the second coupling coefficient corresponds to a second frequency range, the second frequency range being different from the first frequency range.

[0022] According to one example, the first coupling coefficient over the first frequency range is substantially similar to the second coupling coefficient over the second frequency range.

[0023] According to a further embodiment, the method further includes operating the radio frequency signal coupler in the first and second operating modes to maintain a substantially constant insertion loss between the input and output ports over the first and second frequency ranges.

[0024] According to an aspect of the present disclosure, there is provided a radio frequency signal coupler including an input port, an output port, a main inductor coupled between the input port and the output port, and a coupled inductor electromagnetically coupled to the main inductor, the coupled inductor including a first inductor, a second inductor, and a switch configured to couple the first inductor and the second inductor during a first mode of operation and to decouple the first inductor and the second inductor during a second mode of operation.

[0025] According to one embodiment, the switch is configured to couple the first inductor and the second inductor during a first mode of operation to provide a first coupling coefficient, and to decouple the first inductor and the second inductor during a second mode of operation to provide a second coupling coefficient.

[0026] According to another embodiment, the first operating mode corresponds to a first frequency range and the second operating mode corresponds to a second frequency range, the second frequency range being different from the first frequency range.

[0027] According to one example, the first coupling coefficient over the first frequency range is substantially similar to the second coupling coefficient over the second frequency range.

[0028] According to another example, the radio frequency coupler operates in the first and second operating modes to maintain a substantially constant insertion loss between the input and output ports over the first and second frequency ranges.

[0029] According to a further example, the radio frequency signal coupler is configured as a bidirectional coupler, with the input port and the output port each configured to receive an input radio frequency signal and to provide an output radio frequency signal.

[0030] According to a further embodiment, the radio frequency signal coupler further includes at least one forward output port and a reverse output port, and a coupled inductor is coupled between the at least one forward output port and the reverse output port.

[0031] According to one example, at least one forward output port is configured to provide a forward coupled signal when an input radio frequency signal is received at the input port.

[0032] According to another example, the radio frequency signal coupler operates in the first and second modes of operation to maintain a power level of the forward coupled signal substantially constant across the first and second frequency ranges.

[0033] According to a further example, the reverse output port is configured to provide a reverse coupled signal when an input radio frequency signal is received at the output port.

[0034] According to another example, the radio frequency signal coupler operates in the first and second modes of operation to maintain a power level of the backward coupled signal substantially constant across the first and second frequency ranges.

[0035] According to another embodiment, at least one of the forward output port and the reverse output port are selectively coupled to a common output port.

[0036] According to some examples, at least one of the forward output port and the reverse port is selectively coupled to an adjustable termination circuit, and according to these examples, the impedance value provided by the adjustable termination circuit is adjusted based on the frequency of the input radio frequency signal.

[0037] According to another embodiment, the coupled inductor includes a third inductor, and the switch is configured to couple the third inductor to the first inductor and / or the second inductor during a third operating mode corresponding to a third frequency range, the third frequency range being different from the first frequency range and the second frequency range. According to a further embodiment, the switch is configured to couple the third inductor to the first inductor and / or the second inductor during the third operating mode to provide a third coupling coefficient.

[0038] According to another aspect of the present disclosure, there is provided a method of operating a radio frequency signal coupler, the method including receiving a radio frequency signal at one of an input port and an output port, applying the radio frequency signal to a main inductor coupled between the input port and the output port, electromagnetically coupling a portion of the radio frequency signal to a coupled inductor, the coupled inductor including a first inductor and a second inductor, and operating a switch to couple the first inductor and the second inductor during a first mode of operation and to decouple the first inductor and the second inductor during a second mode of operation.

[0039] According to one embodiment, operating the switch to couple the first inductor and the second inductor during the first mode of operation further includes providing a first coupling coefficient during the first mode of operation.

[0040] According to one example, the first coupling coefficient corresponds to a first frequency range.

[0041] According to one embodiment, operating the switch to decouple the first inductor and the second inductor during the second mode of operation further includes providing a second coupling coefficient during the second mode of operation.

[0042] According to one example, the second coupling coefficient corresponds to a second frequency range, the second frequency range being different from the first frequency range.

[0043] According to one example, the first coupling coefficient over the first frequency range is substantially similar to the second coupling coefficient over the second frequency range.

[0044] According to a further embodiment, the method further includes operating the radio frequency signal coupler in the first and second operating modes to maintain a substantially constant insertion loss between the input and output ports over the first and second frequency ranges.

[0045] According to a further aspect of the present disclosure, there is provided a radio frequency signal coupler including an input port, an output port, a main inductance coupled between the input port and the output port, and a coupling inductance electromagnetically coupled to the main inductance, the coupling inductance including a first inductance, a second inductance, and a switch configured to couple the first inductance and the second inductance during a first mode of operation and to decouple the first inductance and the second inductance during a second mode of operation.

[0046] In some examples, the first inductance and the second inductance may be transmission lines or inductors. [Brief explanation of the drawings]

[0047] Various aspects of at least one embodiment are described below with reference to the accompanying drawings, which are not intended to be drawn to scale. The drawings are included to provide illustration and a further understanding of various aspects and embodiments, and are incorporated into and constitute a part of this specification, but are not intended to define the limits of the invention. In the drawings, identical or nearly identical components shown in various drawings are each represented by the same numeral. For purposes of clarity, not every component is labeled in every drawing.

[0048] [Figure 1] FIG. 2 is a block diagram of a front-end module. [Figure 2] FIG. 2 is a schematic diagram of a radio frequency coupler. [Figure 3] 1 is a schematic diagram of a radio frequency coupler according to aspects described herein. [Figure 4A] 1 is a schematic diagram of a radio frequency coupler operating in a first mode of operation in accordance with aspects described herein. [Figure 4B] FIG. 2 is a schematic diagram of a radio frequency coupler operating in a second mode of operation in accordance with aspects described herein. [Figure 5] 1 is a set of graphs illustrating the performance of a radio frequency combiner according to aspects described herein. [Figure 6] 1 is a schematic diagram of a radio frequency coupler array according to aspects described herein. [Figure 7A] 1 is a schematic diagram of a radio frequency coupler array operating in a first state according to aspects described herein. [Figure 7B] FIG. 2 is a schematic diagram of a radio frequency coupler array operating in a second state according to aspects described herein. [Figure 7C] FIG. 10 is a schematic diagram of a radio frequency coupler array operating in a third state in accordance with aspects described herein. [Figure 7D] FIG. 10 is a schematic diagram of a radio frequency coupler array operating in a fourth state in accordance with aspects described herein. [Figure 8] 1 is a layout of a radio frequency combiner in accordance with aspects described herein. DETAILED DESCRIPTION OF THE INVENTION

[0049] Aspects and examples are directed to bidirectional couplers and components thereof, as well as devices, modules and systems incorporating them.

[0050] It should be understood that the method and apparatus embodiments described herein are not limited in their application to the details of construction and arrangement set forth in the following description or illustrated in the accompanying drawings. These methods and apparatus may be implemented in other embodiments and may be practiced or carried out in various ways. Specific implementation examples are provided herein for illustrative purposes only and are not intended to be limiting. Furthermore, the phraseology and terminology used herein are for purposes of description and should not be considered limiting. The use of "including," "comprising," "having," "including," and variations thereof herein is meant to encompass the subsequently listed items and equivalents as well as additional items. References to "or" and "or" are interpreted inclusively, and any items described using "or" and "or" may refer to either one, more than one, or all of the listed items.

[0051] FIG. 1 is a block diagram illustrating an example of a typical arrangement of a radio frequency (RF) "front-end" subsystem or module (FEM) 100 that may be used in a communications device, such as a mobile phone, to transmit and receive RF signals. The FEM 100 shown in FIG. 1 includes a transmit path (TX) configured to provide a signal to an antenna for transmission, and a receive path (RX) configured to receive a signal from the antenna. In the transmit path (TX), a power amplifier module 110 provides gain to an RF signal 105 input to the FEM 100 via an input port 101 to generate an amplified RF signal. The power amplifier module 110 may include one or more power amplifiers (PAs).

[0052] The FEM 100 further includes a filtering subsystem or module 120, which may include one or more filters. A directional coupler 130 may be used to extract a portion of power from an RF signal traveling between the power amplifier module 110 and an antenna 140 connected to the FEM 100. The antenna 140 may transmit and receive RF signals. A switching circuit 150, also referred to as an antenna switch module (ASM), may be used to switch the FEM 100 between transmit and receive modes, for example, between different transmit or receive frequency bands. In certain examples, the switching circuit 150 may operate under the control of a controller 160. As shown, the directional coupler 130 may be located between the filtering subsystem 120 and the switching circuit 150. In other examples, the directional coupler 130 may be located between the power amplifier module 110 and the filtering subsystem 120 or between the switching circuit 150 and the antenna 140.

[0053] The FEM 100 may also include a receive path (RX) configured to process signals received by the antenna 140 and provide the received signals to a signal processor (e.g., a transceiver) via an output port 171. The receive path (RX) may include one or more low noise amplifiers (LNAs) 170 to amplify signals received from the antenna. Although not shown, the receive path (RX) may also include one or more filters to filter the received signals.

[0054] As described above, directional couplers (e.g., directional coupler 130) may be used in front-end module (FEM) products such as wireless transceivers, wireless handsets, etc. For example, directional couplers may also be used to detect and monitor RF output power. When an RF signal generated by an RF source is applied to a load, such as an antenna, a portion of the RF signal may be reflected from the load back to the RF source. An RF coupler may be included in the signal path between the RF source and the load to provide an indication of the forward RF power of the RF signal traveling from the RF source to the load and / or the reverse RF power reflected from the load. RF couplers include, for example, directional couplers, bidirectional couplers, multi-band couplers (e.g., dual-band couplers), etc.

[0055] Referring to FIG. 2 , an RF coupler 200 typically has a power input port 202, a power output port 204, a coupled port 206, and an isolated port 208. The electromagnetic coupling mechanism, which may include inductive or capacitive coupling, is typically provided by two parallel or overlapping transmission lines, such as microstrip, stripline, coplanar line, etc. The transmission line 210 extending between the power input port 202 and the power output port 204 is referred to as the main line and may provide a majority of the signal from the power input port 202 to the power output port 204. The transmission line 212 extending between the coupled port 206 and the isolated port 208 is referred to as the coupled line and may be used to extract a portion of the power traveling between the power input port 202 and the power output port 204 for measurement. In some examples, the amount of inductance provided by each of the transmission lines 210, 212 corresponds to the length of each transmission line. In certain instances, inductor coils may be used in place of the transmission lines 210, 212.

[0056] When termination impedance 214 is presented to isolated port 208 (shown in FIG. 2 ), a representation of the forward RF power traveling from power input port 202 to power output port 204 is provided to coupled port 206. Similarly, when termination impedance is presented to coupled port 206, a representation of the reverse RF power traveling from power output port 204 to power input port 202 is provided to coupled port 206, which is now effectively an isolated port for the reverse RF power. Termination impedance 214 is typically implemented with a 50 ohm shunt resistor in various conventional RF couplers, although in other examples, termination impedance 214 may provide different impedance values ​​for particular operating frequencies. In some examples, termination impedance 214 may be adjustable to support multiple operating frequencies.

[0057] In one example, the RF coupler 200 is configured to provide a coupling coefficient corresponding to the mutual coupling of the transmission line 210 (or the first inductor coil) to the transmission line 212 (or the second inductor coil) and the capacitive coupling of the transmission line 210 (or the first inductor coil) to the transmission line 212 (or the second inductor coil). In some examples, the coupling coefficient may be a function of the spacing between the transmission lines 210, 212 and the inductances of the transmission lines 210, 212. In many cases, the coupling coefficient increases as the frequency increases. As the coupling coefficient increases, more power is coupled from the main line (i.e., the transmission line 210) to the coupled line (i.e., the transmission line 212), increasing the insertion loss of the RF coupler 200.

[0058] Therefore, RF couplers are typically designed to achieve a desired coupling coefficient at a specific frequency (or band). However, in some cases, RF couplers are bidirectional and configured for use in multimode and multifrequency applications. For example, an RF coupler may be included in an FEM configuration (e.g., FEM 100 of FIG. 1) that operates in a first and a second operating mode. In one example, the first operating mode corresponds to low-frequency signals (e.g., 1 GHz) and the second operating mode corresponds to high-frequency signals (e.g., 3 GHz). In some examples, when an RF coupler is designed to achieve a desired coupling coefficient in the first operating mode, the coupling coefficient may be stronger than intended or desired in the second operating mode. Therefore, an attenuator may be used to reduce the coupled power in the second operating mode. Similarly, if the insertion loss of the RF coupler increases in the second operating mode, the output power of the power amplifier module 110 (or other RF source) may increase in the second operating mode to compensate for the increased insertion loss.

[0059] In some examples, including an attenuator to reduce coupled power during the second operating mode (i.e., the high-frequency mode) may increase the footprint of the RF coupler and the overall package size of the FEM. Additionally, attenuating the coupled power during the second operating mode may reduce the accuracy of monitoring the output power provided by the RF coupler. For example, the attenuation provided by the attenuator may not compensate for the exact amount of excess power corresponding to the increased coupling coefficient, and the exact value of the attenuation provided by the attenuator may change. Similarly, a bypass switch may be required to bypass the attenuator during the first operating mode (i.e., the low-frequency mode). The bypass switch not only occupies extra space but may also introduce additional losses into the coupled power signal path. Additionally, operating the power amplifier module 110 (or other RF source) to provide high output power during the second operating mode may result in reduced efficiency of the power amplifier module 110 and increased power consumption of the FEM 100.

[0060] Alternatively, to support the first and second modes of operation, FEM 100 can be configured to include separate RF couplers for each mode. For example, FEM 100 can include a first RF coupler designed to achieve a desired coupling coefficient during the first mode of operation and a second RF coupler designed to achieve a desired coupling coefficient during the second mode of operation. However, including separate RF couplers can increase the footprint and / or package size of FEM 100. Additionally, switching circuitry required to switch between the RF couplers can also increase the footprint and / or package size of FEM 100 and introduce additional loss into the signal path.

[0061] Therefore, an improved dual-directional coupler is provided herein. In at least one embodiment, the dual-directional coupler includes a switchable inductor configured to provide an adjustable coupling coefficient. In some examples, the dual-directional coupler is configured to support a range of signal frequencies. In certain examples, the coupling coefficient is adjusted to minimize insertion loss over the range of signal frequencies while maintaining a substantially constant coupled power level.

[0062] 3 is a schematic diagram of a bidirectional coupler 300 in accordance with aspects described herein. As shown, the coupler 300 includes a main transmission line 302, a coupled transmission line 304, and a switch 306. In one example, the coupled transmission line 304i includes a first segment 304a and a second segment 304b. In some examples, the first segment 304a and the second segment 304b are transmission lines corresponding to switchable inductors. The switch 306 operates to selectively couple the first segment 304a to the second segment 304b to vary the length (i.e., inductance) of the coupled transmission line 304.

[0063] In one example, the main transmission line 302 includes a first port (CPL_IN) and a second port (CPL_ANT), and the coupled transmission line 304 includes a first forward port (CPL_FL), a second forward port (CPL_FH), and a reverse port (CPL_R). In some examples, the first port (CPL_IN) of the main transmission line 302 is configured to be coupled to an output of a filter or amplifier of the FEM (e.g., the filtering subsystem 120 or the power amplifier module 110 of the FEM 100). Similarly, the second port (CPL_ANT) of the main transmission line 302 may be configured to be coupled to an input of a switch / antenna port of the FEM (e.g., a port connected to the switching circuit 150 or the antenna 140 of the FEM 100).

[0064] In some examples, when a radio frequency signal is applied to a first port (CPL_IN) of the main transmission line 302, the signal is output via a second port (CPL_ANT) of the main transmission line 302, providing a coupled signal at the first or second forward port (CPL_FL, CPL_FH) of the coupled transmission line 304. Similarly, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, the signal is output via the first port (CPL_IN) of the main transmission line 302, providing a coupled signal at the reverse port (CPL_R) of the coupled transmission line 304.

[0065] As described above, the switch 306 is operable to selectively couple the first segment 304 a and the second segment 304 b of the transmission line 304 to vary the length (i.e., inductance) of the coupled transmission line 304. In one example, the switch 306 is configured to selectively couple the first forward port (CPL_FL) of the first segment 304 a to the switch port (CPL_SWT) of the second segment 304 b to couple the first segment 304 a and the second segment 304 b of the coupled transmission line 304. Thus, the coupler 300 is configured to operate in different operating modes corresponding to the state of the switch 306. For example, in a first operating mode, the switch 306 is on (i.e., closed) to couple the first segment 304 a of the coupled transmission line 304 to the second segment 304 b of the coupled transmission line 304. Similarly, in the second mode of operation, switch 306 is turned off (ie, open) to decouple first segment 304 a of coupled transmission line 304 from second segment 304 b of coupled transmission line 304 .

[0066] 4A and 4B are schematic diagrams of a bidirectional coupler 300 operating in a first mode and a second mode in accordance with aspects described herein. As shown in FIG. 4A , in the first mode of operation, the switch 306 is on (i.e., closed) to couple the first segment 304 a and the second segment 304 b of the coupled transmission line 304. In one example, the first segment 304 a and the second segment 304 b are coupled together, the coupled transmission line 304 has a first length L1, and the coupler 300 has a first coupling coefficient CF1 corresponding to the first length L1. In some examples, the first length L1 of the coupled transmission line 304 corresponds to the coupled length of the first segment 304 a and the second segment 304 b of the coupled transmission line 304. Thus, when a radio frequency signal is applied to the first port (CPL_IN) of the main transmission line 302, a coupled signal is provided to the second forward port (CPL_FH) of the coupled transmission line 304 via the first segment 304a and the second segment 304b of the coupled transmission line 304. Similarly, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, a coupled signal is provided to the reverse port (CPL_R) of the coupled transmission line 304 via the first segment 304a and the second segment 304b of the coupled transmission line 304.

[0067] 4B , in a second mode of operation, the switch 306 is turned off (i.e., open) to decouple the first segment 304 a and the second segment 304 b of the coupled transmission line 304. In one example, when the first segment 304 a and the second segment 304 b are decoupled, the coupled transmission line 304 has a second length L2, and the coupler 300 has a second coupling coefficient CF2 corresponding to the second length L2. In some examples, the second length L2 of the coupled transmission line 304 corresponds to the length of the first segment 304 a of the coupled transmission line 304. Therefore, when a radio frequency signal is applied to the first port (CPL_IN) of the main transmission line 302, a coupled signal is provided to the first forward port (CPL_FL) of the coupled transmission line 304 via the first segment 304 a of the coupled transmission line 304. Similarly, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, a coupled signal is provided to the reverse port (CPL_R) of the coupled transmission line 304 via the first segment 304a of the coupled transmission line 304.

[0068] As described above, the length (i.e., L1) of the coupled transmission line 304 in the first operating mode is longer than the length (i.e., L2) of the coupled transmission line 304 in the second operating mode. Therefore, the coupling coefficient (i.e., CF1) of the coupler 300 in the first operating mode is greater than the coupling coefficient (i.e., CF2) of the coupler 300 in the second operating mode. As the coupling coefficient increases with frequency, the coupler 300 switches between the first and second operating modes to minimize insertion loss based on the frequency of the signal applied to the main transmission line 302. For example, for a lower frequency signal, the coupler 300 may operate in the first operating mode (i.e., a larger coupling coefficient CF1). Similarly, for an upper frequency signal, the coupler 300 may operate in the second operating mode (i.e., a smaller coupling coefficient CF2).

[0069] 5 shows several graphs of simulated performance results of a dual-directional coupler according to aspects described herein. In one example, graph 510 includes the coupling coefficient of dual-directional coupler 300 over frequency, and graph 520 shows the insertion loss of dual-directional coupler 300 over frequency.

[0070] In one example, a first trace 512 of graph 510 represents the coupling coefficient of coupler 300 while operating in a first operating mode (i.e., CF1). Similarly, a second trace 514 of graph 510 represents the coupling coefficient of coupler 300 while operating in a second operating mode (i.e., CF2). As shown, due to the length of coupled transmission line 304, the first coupling coefficient CF1 remains greater than the second coupling coefficient CF2 over the entire frequency sweep from 0.5 GHz to 4 GHz. As described above, coupler 300 may operate in a first operating mode and a second operating mode based on frequency. In one example, coupler 300 operates in the first operating mode for a first frequency range 516 (approximately 0.5 GHz to 1.5 GHz) and in the second operating mode for a second frequency range 518 (approximately 1.5 GHz to 2.75 GHz). By switching between the first and second operating modes based on frequency, the coupler 300 can provide a substantially constant coupling coefficient across the frequency ranges 516, 518. For example, the coupler 300 can provide a coupling coefficient of approximately −27.1 dB at approximately 0.6 GHz (i.e., the first frequency range 516) while operating in the first operating mode, and a coupling coefficient of approximately −25.1 dB at approximately 1.7 GHz (i.e., the second frequency range 518) while operating in the second operating mode. In certain examples, the coupler 300 can provide a coupling coefficient that varies by less than ±3 dB across the entire operating frequency range (e.g., 0.5 GHz to 3 GHz). In some examples, the substantially constant coupling coefficient enables the coupler 300 to provide coupled power at the forward and reverse ports (CPL_FL, CPL_FH, CPL_R) of the coupled transmission line 304 that is at a substantially constant power level across frequency.

[0071] In one example, a first trace 522 of graph 520 represents the insertion loss of coupler 300 while operating in a first operating mode (i.e., CF1), and a second trace 524 represents the insertion loss of coupler 300 while operating in a second operating mode (i.e., CF2). In some examples, maintaining a substantially constant coupling coefficient across frequency can minimize the insertion loss of coupler 300. For example, coupler 300 may have an insertion loss of approximately −0.10 dB at approximately 1.5 GHz (i.e., a frequency within first frequency range 516) while operating in the first operating mode, and an insertion loss of approximately −0.12 dB at approximately 2.7 GHz (i.e., a different frequency within second frequency range 518) while operating in the second operating mode. In certain examples, the insertion loss of coupler 300 is less than −0.15 dB across the entire operating frequency range (e.g., 0.5 GHz to 3 GHz). In some examples, minimizing insertion loss across frequency allows radio frequency signals to be applied at a substantially constant power level across frequency to the first and second ports (CPL_IN, CPL_ANT) of the main transmission line 302. Additionally, return loss in the main transmission line 302 can remain substantially unchanged when switching between the first and second modes of operation.

[0072] As described above, the coupling coefficient of the coupler 300 can be adjusted to minimize insertion loss across frequency while maintaining a substantially constant power level of the combined signal provided to the forward and reverse output ports (CPL_FL, CPL_FH, and CPL_R). Therefore, the coupler 300 can be integrated into a device (e.g., the FEM 100) without the use of extra components (e.g., attenuators) to adjust the power level of the combined signal. Similarly, the RF source (e.g., the power amplifier module 110) providing the input signal to the coupler 300 can be operated at a constant output power level across frequency, thereby improving the efficiency of the power amplifier module 110 and / or the power consumption of the FEM 100. Additionally, the compact footprint of the coupler 300 can reduce the footprint or package size of the FEM 100.

[0073] In some examples, the bidirectional coupler 300 can be arranged with additional components (e.g., adjustable termination components) to support multi-mode operation. Similarly, the coupler 300 can be arranged with additional components to support integration into existing FEM architectures and layouts. FIG. 6 illustrates a bidirectional coupler 600 in accordance with aspects described herein. In one example, the coupler arrangement 600 includes the bidirectional coupler 300, an adjustable termination circuit 602, and multiple switches S1-S6.

[0074] As described above, the coupler 300 includes a main transmission line 302 having a first port (CPL_IN) and a second port (CPL_ANT), a coupled transmission line 304 having a first forward port (CPL_FL), a second forward port (CPL_FH), and a reverse port (CPL_R), and a switch 306 configured to selectively couple a first segment 304a and a second segment 304b of the coupled transmission line 304.

[0075] In one example, the first switch S1 is configured to selectively couple the reverse port (CPL_R) of the coupled transmission line 304 to the adjustable termination circuit 602, the second switch S2 is configured to selectively couple the first forward port (CPL_FL) of the coupled transmission line 304 to the adjustable termination circuit 602, and the third switch S3 is configured to selectively couple the second forward port (CPL_FH) of the coupled transmission line 304 to the adjustable termination circuit 602. Similarly, the fourth switch S4 is configured to selectively couple the reverse port (CPL_R) of the coupled transmission line 304 to the common output (CPL_OUT), the fifth switch S5 is configured to selectively couple the first forward port (CPL_FL) of the coupled transmission line 304 to the common output (CPL_OUT), and the sixth switch S6 is configured to selectively couple the second forward port (CPL_FH) of the coupled transmission line 304 to the common output (CPL_OUT).

[0076] In some examples, the adjustable termination circuit 602 is selectively coupled to multiple ports of the combiner 300 to control the directivity of the combiner. For example, the adjustable termination circuit 602 may be coupled to a port corresponding to an isolation port in each operating mode of the combiner 300. In one example, when the combiner 300 provides forward coupling, the adjustable termination circuit 602 may be coupled to the reverse port (CPL_R) of the coupled transmission line 304. Similarly, when the combiner 300 provides reverse coupling, the adjustable termination circuit 602 may be coupled to one of the forward ports (CPL_FL, CPL_FH) of the coupled transmission line 304. In one example, the adjustable termination circuit 602 includes at least one adjustable / tunable RLC (resistive-inductive-capacitive) circuit. The adjustable / tunable RLC includes one or more tunable resistive, inductive, or capacitive elements, or a combination thereof. In some examples, the adjustable termination circuit 602 is adjusted / tuned based on the operating mode of the combiner 300. For example, during a first mode of operation, the adjustable termination circuit 602 may be adjusted to provide a first termination impedance optimized for lower frequency signals (e.g., first frequency range 516). Similarly, during a second mode of operation, the adjustable termination circuit 602 may be adjusted to provide a second termination impedance optimized for upper frequency signals (e.g., second frequency range 518). In certain examples, the adjustable termination circuit 602 may be adjusted to provide a termination impedance for a particular signal frequency.

[0077] In some examples, the coupling coefficient of the coupler 300 can be adjusted to account for losses associated with the switches S1-S6. For example, the width and / or length of the first segment 304a and the second segment 304b of the coupled transmission line 304 can be adjusted to increase or decrease the coupling coefficient of the coupler 300. In certain examples, the spacing between the main transmission line 302 and the coupled transmission line 304 can be adjusted to increase or decrease the coupling coefficient of the coupler 300.

[0078] 7A-7D are schematic diagrams of a bidirectional coupler array 600 operating in various states in accordance with aspects described herein.

[0079] FIG. 7A illustrates a first state of the bidirectional coupler array 600. In one example, the first state corresponds to weak coupling in the forward direction. In some examples, the bidirectional coupler array 600 may operate in the first state to provide forward coupling for upper frequency signals (e.g., the second frequency range 518). As shown, when the coupler 300 operates in the second mode of operation, the switch 306 is turned off (i.e., open), decoupling the first segment 304a and the second segment 304b of the coupled transmission line 304. Thus, when a radio frequency signal is applied to the first port (CPL_IN) of the main transmission line 302, the coupled signal is provided to the first forward port (CPL_FL) of the coupled transmission line 304 via the first segment 304a of the coupled transmission line 304. In one example, the fifth switch S5 is turned on (i.e., closed), directing the coupled signal from the first forward port (CPL_FL) to the common output port (CPL_OUT). Additionally, the first switch S1 is turned on (i.e., closed) to couple the reverse port (CPL_R) of the coupled transmission line 304 to the adjustable termination circuit 602. When the coupler 300i is operating in the second mode of operation, the adjustable termination circuit 602 can be configured to provide an optimized second termination impedance for the upper frequency signal during the first state of the coupler array 600.

[0080] 7B illustrates a second state of the bidirectional coupler array 600. In one example, the second state corresponds to strong coupling in the forward direction. In some examples, the bidirectional coupler array 600 may operate in the second state to provide forward coupling for lower frequency signals (e.g., in the first frequency range 516). As illustrated, when the coupler 300 operates in the first mode of operation, the switch 306 is turned on (i.e., closed) to couple the first segment 304a and the second segment 304b of the coupled transmission line 304. Thus, when a radio frequency signal is applied to the first port (CPL_IN) of the main transmission line 302, the coupled signal is provided to the second forward port (CPL_FH) of the coupled transmission line 304 via the first segment 304a and the second segment 304b of the coupled transmission line 304. In one example, the sixth switch S6 is turned on (i.e., closed) to direct the coupled signal from the second forward port (CPL_FH) to the common output port (CPL_OUT). Additionally, the first switch S1 is turned on (i.e., closed) to couple the reverse port (CPL_R) of the coupled transmission line 304 to the adjustable termination circuit 602. When the combiner 300 is operating in the first mode of operation, the adjustable termination circuit 602 can be configured to provide an optimized first termination impedance for lower frequency signals during the second state of the combiner array 600.

[0081] FIG. 7C illustrates a third state of the bidirectional coupler array 600. In one example, the third state corresponds to weak coupling in the reverse direction. In some examples, the bidirectional coupler array 600 can operate in the third state to provide reverse coupling for upper frequency signals (e.g., the second frequency range 518). As shown, when the coupler 300 operates in the second mode of operation, the switch 306 is turned off (i.e., open) to decouple the first segment 304a and the second segment 304b of the coupled transmission line 304. Therefore, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, the coupled signal is provided to the reverse port (CPL_R) of the coupled transmission line 304 via the first segment 304a of the coupled transmission line 304. In one example, the fourth switch S4 is turned on (i.e., closed) to direct the coupled signal from the reverse port (CPL_R) to the common output port (CPL_OUT). Additionally, the second switch S2 is turned on (i.e., closed) to couple the first forward port (CPL_FL) of the coupled transmission line 304 to the adjustable termination circuit 602. When the coupler 300i is operating in the second mode of operation, the adjustable termination circuit 602 can be configured to provide an optimized second termination impedance for the upper frequency signal during a third state of the coupler array 600.

[0082] 7D illustrates a fourth state of the bidirectional coupler array 600. In one example, the fourth state corresponds to strong coupling in the reverse direction. In some examples, the bidirectional coupler array 600 may operate in the fourth state to provide reverse coupling for lower frequency signals (e.g., the first frequency range 516). As shown, when the coupler 300 operates in the first mode of operation, the switch 306 is turned on (i.e., closed) to couple the first and second segments 304a and 304b of the coupled transmission line 304. Therefore, when a radio frequency signal is applied to the second port (CPL_ANT) of the main transmission line 302, the coupled signal is provided to the reverse port (CPL_R) of the coupled transmission line 304 via the first and second segments 304a and 304b of the coupled transmission line 304. In one example, the fourth switch S4 is turned on (i.e., closed) to direct the coupled signal from the reverse port (CPL_R) to the common output port (CPL_OUT). Additionally, the third switch S3 is turned on (i.e., closed) to couple the second forward port (CPL_FL) of the coupled transmission line 304 to the adjustable termination circuit 602. When the coupler 300 is operating in the first mode of operation, the adjustable termination circuit 602 can be configured to provide an optimized first termination impedance for lower frequency signals during a fourth state of the coupler array 600.

[0083] While the bidirectional coupler 300 is described above as having two selectable segments (i.e., the first segment 304a and the second segment 304b), it should be understood that the bidirectional coupler 300 may be configured with a coupled transmission line having a different number of segments. For example, the coupler 300 may be configured with a coupled transmission line having three segments to provide optimized coupling performance for three different signal frequencies (or bands / ranges). Thus, a third segment may be coupled to the first segment 304a and / or the second segment 304b of the coupled transmission line 304 during a third operating mode to provide a third coupling coefficient. In some examples, additional switches may be included to selectively couple multiple segments of the coupled transmission line.

[0084] Similarly, while the bidirectional coupler 300 is described above as having a main transmission line 302 and a coupled transmission line 304, it should be understood that the bidirectional coupler 300 may also be configured with separate inductors (i.e., having coils or windings). For example, the bidirectional coupler 300 may be configured with a main inductor corresponding to the main transmission line 302 and a coupled inductor corresponding to the coupled transmission line 304. In some examples, the coupled inductor may include two or more inductors corresponding to the first segment 304a and the second segment 304b of the coupled transmission line 304. In certain examples, the main inductor may be referred to as the primary winding of the bidirectional coupler 300, and the coupled inductor may be referred to as the secondary winding of the bidirectional coupler 300.

[0085] Additionally, it should be appreciated that the bidirectional coupler 300 and bidirectional coupler array 600 may be used in a variety of wireless applications. For example, the coupler 300 and coupler array 600 may be configured for use in wireless local area network (WLAN) applications, ultra-wideband (UWB) applications, wireless personal area network (WPAN) applications, 4G cellular applications, and LTE cellular applications.

[0086] In some examples, switch 306 of coupler 300 and / or switches S1-S6 of coupler array 600 may include gallium nitride (GaN), gallium arsenide (GaAs), or silicon germanium (SiGe) transistors. In certain examples, the transistors may be configured as heterojunction bipolar transistors (HBTs), high electron mobility transistors (HEMTs), metal oxide semiconductor field effect transistors (MOSFETs), and / or complementary metal oxide semiconductors (CMOS). In some examples, coupler 300 or coupler array 600, or one or more components of coupler 300 or coupler array 600, may be fabricated using silicon-on-insulator (SOI) technology.

[0087] As described above, the coupler 300 can be arranged in a compact layout. For example, FIG. 8 is a schematic diagram of a layout 800 of the coupled transmission line 304 of the coupler 300 in accordance with aspects described herein. As shown, the first segment 304a and the second segment 304b of the coupled transmission line 304 can be arranged in a compact layout. In one example, the footprint of the coupler 300 can be 50% smaller than an alternative multi-frequency combining solution (e.g., two different couplers).

[0088] Embodiments of the bidirectional coupler 300 and / or bidirectional coupler array 600 described herein can be advantageously used in a variety of electronic devices. Examples of electronic devices may include, but are not limited to, consumer electronic products, components for consumer electronic products, electronic test equipment, cellular communication infrastructure such as base stations, etc. Examples of electronic devices may include, but are not limited to, routers, gateways, mobile phones such as smartphones, cellular front-end modules, telephones, televisions, computer monitors, computers, modems, handheld computers, laptop computers, tablet computers, e-readers, wearable computers such as smart watches, personal digital assistants (PDAs), appliances such as microwave ovens, refrigerators, etc., automobiles, stereo systems, digital music players such as DVD players, CD players, MP3 players, radios, camcorders, cameras, digital cameras, portable memory chips, healthcare monitoring devices, vehicle electronic systems such as automotive electronic systems or avionics systems, peripheral devices, watches, clocks, etc. Additionally, electronic devices may include unfinished products.

[0089] As noted above, an improved dual-directional coupler is provided herein. In at least one embodiment, the dual-directional coupler includes a switchable inductor configured to provide an adjustable coupling coefficient. In some examples, the dual-directional coupler is configured to support a range of signal frequencies. In certain examples, the coupling coefficient is adjusted to minimize insertion loss over the range of signal frequencies while maintaining a substantially constant coupled power level.

[0090] While several aspects of at least one embodiment have been described above, it should be understood that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the present invention. Accordingly, the foregoing description and drawings are by way of example only, and the scope of the present invention should be determined from proper construction of the appended claims and their equivalents.

Claims

1. 1. A radio frequency signal coupler comprising: An input port; an output port; a main transmission line coupled between the input port and the output port, the main transmission line functioning as a primary winding; a coupled transmission line electromagnetically coupled to the main transmission line and functioning as a secondary winding; Including, The coupled transmission line a first transmission line; a second transmission line; and a switch configured to couple the first transmission line and the second transmission line during a first mode of operation and to decouple the first transmission line and the second transmission line during a second mode of operation; a radio frequency signal coupler including:

2. 2. The radio frequency signal coupler of claim 1, wherein the switch is configured to couple the first transmission line and the second transmission line to provide a first coupling coefficient during the first mode of operation and to decouple the first transmission line and the second transmission line to provide a second coupling coefficient during the second mode of operation.

3. the first mode of operation corresponds to configuring the radio frequency signal coupler to operate within a first frequency range; the second operating mode corresponds to configuring the radio frequency signal coupler to operate within a second frequency range; 3. The radio frequency signal coupler of claim 2, wherein said second frequency range and said first frequency range are different.

4. 4. The radio frequency signal coupler of claim 3, wherein the first coupling coefficient across the first frequency range is within ±3 dB of the second coupling coefficient across the second frequency range.

5. 4. The radio frequency signal coupler of claim 3, wherein the radio frequency signal coupler operates to maintain a substantially constant insertion loss between the input port and the output port across the first frequency range and the second frequency range in the first and second operating modes.

6. 4. The radio frequency signal coupler of claim 3, wherein the radio frequency signal coupler is configured as a bidirectional coupler, the input port and the output port being configured to receive an input radio frequency signal and provide an output radio frequency signal, respectively.

7. further comprising at least one forward output port and one reverse output port; 7. The radio frequency signal coupler of claim 6, wherein the coupled transmission line is coupled between the at least one forward output port and the one reverse output port.

8. 8. The radio frequency signal coupler of claim 7, wherein the at least one forward output port is configured to provide a forward coupled signal when the input radio frequency signal is received at the input port.

9. 9. The radio frequency signal coupler of claim 8, wherein the radio frequency signal coupler operates to maintain a substantially constant power level of the forward coupled signal across the first frequency range and the second frequency range in the first and second operating modes.

10. 8. The radio frequency signal coupler of claim 7, wherein the reverse output port is configured to provide a reverse coupled signal when the input radio frequency signal is received at the output port.

11. 11. The radio frequency signal coupler of claim 10, wherein the radio frequency signal coupler operates to maintain a substantially constant power level of the backward coupled signal across the first frequency range and the second frequency range in the first and second operating modes.

12. 8. The radio frequency signal combiner of claim 7, wherein the at least one forward output port and the one reverse port are selectively coupled to a common output port.

13. 8. The radio frequency signal coupler of claim 7, wherein the at least one forward output port and the one reverse output port are selectively coupled to an adjustable termination circuit.

14. 14. The radio frequency signal coupler of claim 13, wherein the impedance value provided by the adjustable termination circuit is adjusted based on the frequency of the input radio frequency signal.

15. the coupled transmission line includes a third transmission line; the switch is configured to couple the third transmission line to the first transmission line and / or the second transmission line during a third mode of operation corresponding to a third frequency range; 4. The radio frequency signal coupler of claim 3, wherein said third frequency range is different from said first frequency range and said second frequency range.

16. 16. The radio frequency signal coupler of claim 15, wherein the switch is configured to couple the third transmission line to the first transmission line and / or the second transmission line during the third mode of operation to provide a third coupling coefficient.

17. 1. A method of operating a radio frequency signal combiner, comprising: receiving a radio frequency signal at one of the input port and the output port; applying the radio frequency signal to a main transmission line coupled between the input port and the output port, the main transmission line functioning as a primary winding; electromagnetically coupling a portion of the radio frequency signal to a coupled transmission line that includes a first transmission line and a second transmission line and that functions as a secondary winding; operating a switch to couple the first transmission line and the second transmission line during a first mode of operation and to decouple the first transmission line and the second transmission line during a second mode of operation; A method comprising:

18. 20. The method of claim 17, wherein operating the switch to couple the first transmission line and the second transmission line during the first mode of operation further comprises providing a first coupling coefficient to the radio frequency signal coupler.

19. 20. The method of claim 18, wherein the first coupling coefficient corresponds to a first frequency range.

20. 20. The method of claim 19, wherein operating the switch to decouple the first transmission line and the second transmission line during the second mode of operation further comprises providing a second coupling coefficient for the radio frequency signal coupler.

21. the second coupling coefficient corresponds to a second frequency range; 21. The method of claim 20, wherein the second frequency range and the first frequency range are different.

22. 22. The method of claim 21, wherein the first coupling coefficient across the first frequency range is within ±3 dB of the second coupling coefficient across the second frequency range.

23. 22. The method of claim 21, further comprising: operating the radio frequency signal coupler to maintain a substantially constant insertion loss between the input port and the output port across the first frequency range and the second frequency range in the first and second operating modes.

24. 1. A radio frequency signal coupler comprising: An input port; an output port; a main inductance coupled as a primary winding between the input port and the output port; a coupled inductance that is electromagnetically coupled to the main inductance as a secondary winding; Including, The coupling inductance is a first inductance; A second inductance; a switch configured to couple the first inductance and the second inductance during a first mode of operation and to decouple the first inductance and the second inductance during a second mode of operation; a radio frequency signal coupler including:

Images