Directional coupler with multiple arrangements of termination

Abstract

To provide a system, a method, a radio frequency signal coupler, and a directional coupler for improving coupler performance using multiple arrangements of termination.SOLUTION: A directional coupler 300 includes an input port 302, an output port 304, a main transmission line 310 extending between the input port and the output port, a coupled transmission line 312 electromagnetically coupled to the main transmission line, at least one coupled port 306 coupled to the coupled transmission line, and a plurality of termination ports 308a, 308b connected to the coupled transmission line. The respective termination ports are connected to the coupled transmission line at different locations to provide a plurality of coupling factors corresponding to a plurality of signal frequencies.SELECTED DRAWING: Figure 3

Description

Technical Field

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[0001] Background 1. Related Applications This application claims priority and the benefit thereof based on U.S. Provisional Application No. 63 / 195,823, filed on June 2, 2021, entitled DIRECTIONAL COUPLER WITH MULTIPLE ARRANGEMENTS OF TERMINATION, and the entire disclosure of this application is incorporated herein by reference.

Background Art

[0002] 2. Field of the Invention This disclosure generally relates to directional couplers. More specifically, aspects of this disclosure relate to systems and methods for improving the performance of a coupler using multiple termination configurations.

Summary of the Invention

Means for Solving the Problems

[0003] Summary According to some aspects of this disclosure, a radio frequency signal coupler is provided. The radio frequency signal coupler includes an input port, an output port, a main transmission line extending between the input port and the output port, a coupled transmission line electromagnetically coupled to the main transmission line, at least one coupled port coupled to the coupled transmission line, and a plurality of termination ports connected to the coupled transmission line. Each of the plurality of termination ports is connected to the coupled transmission line at a different position to provide a plurality of coupling coefficients corresponding to a plurality of signal frequencies.

[0004] In some embodiments, multiple termination impedances are coupled to multiple termination ports. In various embodiments, multiple switches are provided, configured to selectively connect multiple termination impedances to multiple termination ports. In some embodiments, the termination impedances among the multiple termination impedances include fixed impedances and / or adjustable impedances. In some embodiments, the switches among the multiple switches are symmetrically coupled to a coupled transmission line and are configured to selectively couple impedances among the multiple termination impedances based on a radio frequency signal received at an input port or output port.

[0005] In various embodiments, a first termination impedance among a plurality of termination impedances is coupled to a first termination port among a plurality of termination ports, and a second termination impedance among a plurality of termination impedances is coupled to a second termination port among a plurality of termination ports. In some embodiments, the first termination impedance is tuned to a first signal frequency among a plurality of signal frequencies, and the second termination impedance is tuned to a second signal frequency among a plurality of signal frequencies. In many embodiments, the first termination port is connected to the coupling transmission line at a first position to provide a first coupling coefficient corresponding to the first signal frequency, and the second termination port is connected to the coupling transmission line at a second position to provide a second coupling coefficient corresponding to the second signal frequency.

[0006] In some embodiments, the first coupling coefficient corresponds to a first length of the coupled transmission line between a first termination port and at least one coupled port, and the second coupling coefficient corresponds to a second length of the coupled transmission line between a second termination port and at least one coupled port. In many embodiments, the first coupling coefficient is selected to provide a desired level of insertion loss at a first signal frequency, and the second coupling coefficient is selected to provide a desired level of insertion loss at a second signal frequency. In various embodiments, the first coupling coefficient at the first signal frequency is substantially the same as the second coupling coefficient at the second signal frequency.

[0007] In some embodiments, the radio frequency signal coupler is configured to minimize insertion loss between the input port and the output port at first and second signal frequencies. In many embodiments, the at least one coupling port includes a first coupling port configured to provide a first coupled signal when an input radio frequency signal is received at the input port. In various embodiments, the radio frequency signal coupler is configured to maintain a substantially constant power level of the first coupled signal at first and second signal frequencies. In some embodiments, the at least one coupling port includes a second coupling port configured to provide a second coupled signal when an input radio frequency signal is received at the output port. In many embodiments, the radio frequency signal coupler is configured to maintain a substantially constant power level of the second coupled signal at first and second signal frequencies.

[0008] A method for reducing insertion loss in a radio frequency coupler is provided in accordance with several aspects of the present disclosure. The method includes receiving a radio frequency (RF) signal on a first transmission line that is electromagnetically coupled to a second transmission line, the RF signal having a frequency which is one of a first frequency and a second frequency different from the first frequency, and the method further includes inducing an induced RF signal on the second transmission line based on the RF signal, the induced RF signal having one of a first frequency and a second frequency which corresponds to the frequency of the RF signal, and the method further includes terminating an induced RF signal having a first frequency at a first position along the length of the second transmission line in order to provide a first coupled signal having a first coupling coefficient, and terminating an induced RF signal having a second frequency at a second position along the second transmission line in order to provide a second coupled signal having a second coupling coefficient which is substantially identical to the first coupling coefficient.

[0009] In some embodiments, the method includes the step of adjusting at least one impedance among a plurality of impedances coupled to the second transmission line in order to change the coupling coefficient of the first and second transmission lines. In various embodiments, the second transmission line has one or more switches coupled to the plurality of impedances, and the method includes the step of selectively turning the switches on or off based on at least one of the direction or frequency of the RF signal. In many embodiments, the method includes the step of selecting first and second positions in order to maximize directivity at first and second frequencies, to maximize isolation at first and second frequencies, to minimize a first coupling coefficient at first frequency, and to minimize a second coupling coefficient at second frequency.

[0010] Various aspects of at least one embodiment will be described below with reference to the accompanying drawings, which are not intended to be to the correct scale. The drawings are included to illustrate various aspects and embodiments and to provide further understanding, and are incorporated into and form part of this specification, but are not intended to define limitations of the invention. In the drawings, each component that is identical or substantially identical shown in the different drawings is represented by similar numbers. For clarity, not every component in every drawing is referenced. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram of the front-end module. [Figure 2] This is a schematic diagram of a radio frequency coupler. [Figure 3] This is a schematic diagram of a radio frequency coupler relating to the aspect described in this specification. [Figure 4] This is a diagram of a set of graphs showing the performance of a radio frequency coupler in relation to the aspects described herein. [Figure 5] This is a schematic diagram of a radio frequency coupler relating to the aspect described in this specification. [Figure 6] This is a schematic diagram of several impedance termination configurations relating to the aspects described herein. [Figure 7] This is a diagram showing the layout of a radio frequency coupler relating to the aspect described herein. [Figure 8] This is a schematic diagram of a radio frequency coupler relating to the aspect described in this specification. [Figure 9] This is a schematic diagram of a radio frequency coupler relating to the aspect described in this specification. [Figure 10] This is a schematic diagram of a radio frequency coupler relating to the aspect described in this specification. [Figure 11] This is a schematic diagram of a radio frequency coupler relating to the aspect described in this specification. [Figure 12] This is a schematic diagram of a radio frequency coupler relating to the aspect described in this specification. [Modes for carrying out the invention]

[0012] Detailed explanation The aspects and embodiments are directed towards bidirectional couplers and their components, as well as devices, modules, and systems incorporating them.

[0013] It should be understood that the embodiments of the methods and apparatus described herein are not limited to the details of the structure and arrangement of components described below or shown in the accompanying drawings. The methods and apparatus described above are also achievable in other embodiments and can be implemented or performed in a variety of ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to limit. Furthermore, the expressions and terms used herein are for illustrative purposes only and should not be considered limiting. The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof means that they encompass the items listed therein and their equivalents and other items. The “or” statement can be interpreted as comprehensive, meaning that any term described using “or” may refer to one, two or more, or all of the terms described.

[0014] Figure 1 is a block diagram showing a typical configuration example of a radio frequency (RF) "front-end" subsystem or module (FEM) 100, which may be used in a communication device such as a mobile phone to transmit and receive RF signals. The FEM 100 shown in Figure 1 includes a transmit path (TX) configured to provide a signal to an antenna 140 for transmission, and a receive path (RX) for receiving a signal from the antenna 140. In the transmit path (TX), a power amplifier module 110 provides gain to the RF signal 105 input to the FEM 100 via an input port 101, thereby generating an amplified RF signal. The power amplifier module 110 may include one or more power amplifiers (PAs).

[0015] The FEM100 may further include a filtering subsystem or module 120 which may include one or more filters. A directional coupler 130 can be used to extract a portion of the power from the RF signal transmitted between the power amplifier module 110 and the antenna 140 connected to the FEM100. The antenna 140 can transmit and receive RF signals. A switching circuit 150, also called an antenna switching module (ASM), can be used to switch, for example, between the transmit mode and the receive mode of the FEM100, or between different transmit or receive frequency bands. In one example, the switching circuit 150 can be operated under the control of a controller 160. As shown in the figure, 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.

[0016] The FEM100 may also include a receive path (RX) configured to process the signal received by the antenna 140 and provide the received signal to a signal processor (e.g., a transceiver) via the output port 171. The receive path (RX) may include one or more low noise amplifiers (LNAs) 170 for amplifying the signal received from the antenna 140. Although not shown, the receive path (RX) may also include one or more filters for filtering the received signal.

[0017] As described above, a directional coupler (e.g., directional coupler 130) can be used in front-end module (FEM) products such as wireless transceivers, wireless handsets, etc. For example, a directional coupler can 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 towards the RF source. By including an RF coupler in the signal path between the RF source and the load, it is possible to provide an indication of the forward RF power of the RF signal sent from the RF source to the load and / or an indication of the reverse RF power reflected from the load. RF couplers include, for example, directional couplers, bi-directional couplers, multi-band couplers (e.g., dual-band couplers), etc.

[0018] Referring to FIG. 2, RF coupler 200 typically has a power input port 202, a power output port 204, a coupling port 206, and an isolation port 208. An electromagnetic coupling mechanism that may include inductive coupling 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 named the main line and can provide most of the signal from the power input port 202 to the power output port 204. The transmission line 212 extending between the coupling port 206 and the isolation port 208 is named the coupling line and can be used to extract a portion of the power sent 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 one example, an inductor coil may be used instead of the transmission lines 210, 212.

[0019] (As shown in FIG. 2) When the termination impedance 214 is presented at the isolation port 208, an indication of the forward RF power sent from the power input port 202 to the power output port 204 is provided at the coupling port 206. Similarly, when the termination impedance is presented at the coupling port 206, an indication of the reverse RF power sent from the power output port 204 to the power input port 202 is provided at the coupling port 206, which is then effectively an isolation port for the reverse RF power at this time. The termination impedance 214 is typically realized by a 50-ohm shunt resistor in various conventional RF couplers. However, in other examples, the termination impedance 214 may provide different impedance values for specific operating frequencies. In some examples, the termination impedance 214 may be adjustable to support multiple operating frequencies.

[0020] In one example, the RF coupler 200 is configured to provide a coupling coefficient corresponding to the mutual coupling between transmission line 210 (or the first inductor coil) and transmission line 212 (or the second inductor coil) and the capacitive coupling between transmission line 210 (or the first inductor coil) and transmission line 212 (or the second inductor coil). In some examples, the coupling coefficient may be a function of the spacing between transmission lines 210 and 212 and the inductances of transmission lines 210 and 212. Often, the coupling coefficient increases with increasing frequency. As the coupling coefficient increases, more power is coupled from the main line (i.e., transmission line 210) to the coupling line (i.e., transmission line 212), increasing the insertion loss of the RF coupler 200.

[0021] Therefore, RF couplers are typically designed to achieve a desired coupling coefficient at a specific frequency (or band). However, in some cases, RF couplers may be configured for use in multimode, multifrequency applications. For example, an RF coupler may be included in a FEM (e.g., FEM100 in Figure 1) configured to operate in a first and second operating mode. In one example, the first operating mode may correspond to a low-frequency signal (e.g., 1 GHz), and the second operating mode may correspond to a high-frequency signal (e.g., 3 GHz). Thus, the RF coupler may include one or more termination impedances coupled to the isolation port 208 corresponding to the low-frequency and high-frequency signals. However, the RF coupler may be designed to achieve a desired coupling coefficient during the first operating mode, and the coupling coefficient may be stronger than that intended or desired during the second operating mode. Thus, an attenuator may be used to reduce the coupling power during the second operating mode. Similarly, the insertion loss of the RF coupler may increase during the second operating mode, and the output power of the power amplifier module 110 (or another RF source) may be increased during the second operating mode to compensate for the increased insertion loss.

[0022] In some cases, 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 FEM100. In addition, attenuating coupled power during the second operating mode may reduce the accuracy of the output power monitoring 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 vary. Similarly, a bypass switch may be required to bypass the attenuator during the first operating mode (i.e., the low-frequency mode). In addition to occupying extra space, the bypass switch may introduce further losses in the coupled power signal path. Furthermore, operating the power amplifier module 110 (or another RF source) to provide higher output power during the second operating mode may reduce the efficiency of the power amplifier module 110 and increase the power consumption of the FEM100.

[0023] In other examples, the RF coupler may consist of multiple sections of coupling traces that can be connected or disconnected depending on the operating mode (e.g., a first or second operating mode). In one example, the coupling traces are configured to be selectively connected via switches to adjust the coupling coefficient of the RF coupler. In some examples, due to the multiple sections of coupling traces, the RF coupler may have multiple coupling ports, and frequency combiner components (e.g., diplexers, triplexers, n-port multiplexers, etc.) may be used to combine multiple signals into a single output. However, including frequency combiner components may increase the footprint of the RF coupler and the overall package size of the FEM100.

[0024] Alternatively, to support the first and second operating modes, the FEM100 can be configured to include a separate RF coupler for each mode. For example, the FEM100 may include a first RF coupler designed to achieve a desired coupling coefficient during the first operating mode and a second RF coupler designed to achieve a desired coupling coefficient during the second operating mode. However, including separate RF couplers may increase the footprint and / or package size of the FEM100. In addition, the switching circuitry used for switching between RF couplers may also increase the footprint and / or package size of the FEM100 and may introduce additional losses into the signal path.

[0025] Therefore, improved signal couplers are provided herein. In at least one embodiment, the coupler includes a plurality of terminations arranged to provide different coupling coefficients optimized for a given signal frequency range. In some examples, each termination is connected to the coupling line of the coupler at different locations to provide different coupling coefficients. In some examples, the plurality of terminations are configured to maintain a substantially constant coupling power level while minimizing insertion loss over a signal frequency range.

[0026] Figure 3 shows a schematic diagram of a directional coupler 300 relating to the aspect described herein. As shown in the figure, the directional coupler 300 includes an input port 302, an output port 304, a coupling port 306, a first termination port 308a, a second termination port 308b, a main transmission line 310, a coupling transmission line 312, a first termination impedance 314a, and a second termination impedance 314b.

[0027] In one example, the main transmission line 310 is connected between the input port 302 and the output port 304. In some examples, the input port 302 is configured to be coupled to the output of a filter or amplifier of the FEM (e.g., the filtering subsystem 120 or power amplifier module 110 of FEM 100). Similarly, the output port 304 may be configured to be coupled to the input of a switch / antenna port of the FEM (e.g., the switching circuit 150 or a port connected to antenna 140 of FEM 100).

[0028] In one example, the coupled transmission line 312 is coupled between the coupled port 306 and the first termination port 308a. The distance between the coupled port 306 and the first termination port 308a corresponds to a first length L1 (i.e., the length of the coupled transmission line 312). As shown in the figure, the second termination port 308b is connected to the coupled transmission line 312 at a different location from the first termination port 308a. In one example, the distance between the coupled port 306 and the second termination port 308b corresponds to a second length L2.

[0029] In some examples, when a radio frequency signal is applied to the input port 302 of the main transmission line 310, this signal is output via the output port 304 of the main transmission line 310, and the coupled signal is provided to the coupled port 306 of the coupled transmission line 312. As previously mentioned, the first termination port 308a and the second termination port 308b are connected to the coupled transmission line 312 at different locations. In one example, the first termination impedance 314a is optimized (i.e., tuned) for a first frequency, and the second termination impedance 314b is optimized (i.e., tuned) for a second frequency. Thus, when a radio frequency signal is applied to the input port 302 having a first frequency, the coupled transmission line 312 has an effective length corresponding to the distance between the coupled port 306 and the first termination port 308a (i.e., a first length L1). Similarly, when a radio frequency signal is applied to input port 302 having a second frequency, the coupled transmission line 312 has an effective length corresponding to the distance between the coupled port 306 and the second termination port 308b (i.e., the second length L2).

[0030] In one example, the first frequency is lower than the second frequency. Therefore, the directional coupler 300 is configured to provide different coupling coefficients optimized for each of the first and second frequencies. For example, when a radio frequency signal having the first frequency is applied to the input port 302, the directional coupler 300 is configured to provide a first coupling coefficient CF1 corresponding to the first length L1. Similarly, when a radio frequency signal having the second frequency is applied to the input port 302, the directional coupler 300 is configured to provide a second coupling coefficient CF2 corresponding to the second length L2. As shown in Figure 3, the effective length of the coupled transmission line 312 for the radio frequency signal having the first frequency (i.e., L1) is longer than the effective length of the coupled transmission line 312 for the radio frequency signal having the second frequency (i.e., L2). Therefore, the first coupling coefficient CF1 is greater (or stronger) than the second coupling coefficient CF2. Since the coupling coefficient increases with frequency, the stronger coupling coefficient (CF1) and the weaker coupling coefficient (CF2) may have substantially similar values ​​at the first and second frequencies, respectively.

[0031] Figure 4 shows several graphs of simulated performance results for a directional coupler relating to the aspects described herein. Graph 410 represents the coupling coefficient of the directional coupler 300, graph 420 represents the insertion loss of the directional coupler 300, graph 430 represents the isolation of the directional coupler 300, and graph 440 represents the directivity of the directional coupler 300. In one example, the simulated performance results correspond to a configuration of the directional coupler 300 optimized to support a first frequency of 900 MHz and a second frequency of 2.7 GHz.

[0032] In one example, trace 412 in Graph 410 represents the coupling coefficient of the directional coupler 300 over a frequency sweep from 0 GHz to 6 GHz. As shown in the figure, due to the different locations of the first and second termination ports 308a, 308b and the values ​​of the first and second termination impedances 314a, 314b, the coupling coefficient at the first frequency (i.e., CF1) and the coupling coefficient at the second frequency (i.e., CF2) are substantially similar. For example, the directional coupler 300 may provide a coupling coefficient of approximately -20.8 dB at 900 MHz (i.e., the first frequency) and a coupling coefficient of approximately -18.4 dB at 2.7 GHz (i.e., the second frequency). In one example, the directional coupler 300 may provide a coupling coefficient that varies by less than ±2.5 dB between the first and second frequencies. In some examples, substantially similar coupling coefficients allow the directional coupler 300 to provide coupling power to the coupling port 306 of the coupled transmission line 312 at substantially constant power levels for both the first and second frequencies. For comparison, the dashed trace shown in Graph 410 represents the coupling coefficient of a single-terminated coupler as an example (e.g., RF coupler 200 in Figure 2). As shown, the coupling coefficient of the single-terminated coupler at the second frequency (2.7 GHz) is approximately 10 dB higher than the coupling coefficient at the first frequency (900 MHz). Therefore, the single-terminated coupler may exhibit undesirable performance at the second frequency compared to the first frequency, and vice versa.

[0033] In one example, trace 422 in Graph 420 represents the insertion loss of the directional coupler 300 over a frequency sweep from 0 GHz to 6 GHz. As shown in the figure, the insertion loss of the directional coupler 300 can be minimized at both the first and second frequencies by substantially similar coupling coefficients at each of the first and second frequencies. For example, the directional coupler 300 may have an insertion loss of approximately -0.09 dB at 900 MHz (i.e., the first frequency) and an insertion loss of approximately -0.2 dB at 2.7 GHz (i.e., the second frequency). In one example, the insertion loss of the directional coupler 300 may vary by less than ±0.15 dB between the first and second frequencies. In some examples, by minimizing the insertion loss, the radio frequency signal can be supplied to the input port 302 of the main transmission line 310 at a substantially constant power level for both the first and second frequencies. In addition, the return loss in the main transmission line 310 may remain substantially constant between the first and second frequencies. For comparison, the dashed trace shown in Graph 420 represents the insertion loss of a single-terminated coupler as an example (e.g., RF coupler 200 in Figure 2). As shown, the insertion loss of the single-terminated coupler at the second frequency (2.7 GHz) is approximately 0.4 dB greater than the insertion loss at the first frequency (900 MHz). Therefore, the single-terminated coupler may exhibit undesirable performance at the second frequency compared to the first frequency, and vice versa.

[0034] In one example, trace 432 in Graph 430 represents the isolation of the directional coupler 300 over a frequency sweep from 0 GHz to 6 GHz. The isolation of the directional coupler 300 corresponds to the difference in signal power between the input port 302 and the first and second termination ports 308a, 308b. As shown in the figure, due to the different locations of the first and second termination ports 308a, 308b and the values ​​of the first and second termination impedances 314a, 314b, the directional coupler 300 is configured to provide maximum isolation at the first and second frequencies. For example, at 900 MHz (i.e., the first frequency), the directional coupler 300 may provide isolation of approximately -70.0 dB. Similarly, at 2.7 GHz (i.e., the second frequency), the directional coupler 300 may provide isolation of approximately -70.9 dB. For comparison, at an unoptimized frequency (e.g., 3.6 GHz), the directional coupler 300 may provide approximately -19.0 dB of isolation. In one example, the amount of isolation provided by the directional coupler 300 may vary by less than ±1 dB between the first and second frequencies.

[0035] Similarly, trace 442 in Graph 440 represents the directivity of the directional coupler 300 over a frequency sweep from 0 GHz to 6 GHz. The directivity of the directional coupler 300 corresponds to the difference between the coupling coefficient (e.g., Graph 410) and the amount of isolation provided by the coupler (e.g., Graph 430). As shown in the figure, due to the different locations of the first and second termination ports 308a, 308b and the values ​​of the first and second termination impedances 314a, 314b, the directional coupler 300 is configured to have maximum directivity at the first and second frequencies. For example, at 900 MHz (i.e., the first frequency), the directivity of the directional coupler 300 may be approximately 49.2 dB. Similarly, at 2.7 GHz (i.e., the second frequency), the directivity of the coupler 300 may be approximately 52.5 dB. For comparison, at an unoptimized frequency (e.g., 3.6 GHz), the directivity of the directional coupler 300 may be approximately 4.9 dB. In one example, the directivity of the directional coupler 300 may vary by less than ±3.5 dB between the first and second frequencies.

[0036] As previously mentioned, the directional coupler 300 can provide optimized coupling coefficients for each of the first and second frequencies. In some examples, the optimized coupling coefficients may be selected to minimize insertion loss at each of the first and second frequencies while maintaining a substantially constant power level of the coupled signal provided to the coupling port 306. However, in other examples, the optimized coupling coefficients may be selected to give different performance metrics (e.g., insertion loss, coupled power level) at each of the first and second frequencies. In some examples, the directional coupler 300 allows multiple signals to be coupled simultaneously (e.g., carrier aggregation). Therefore, the directional coupler 300 may be integrated into the device (e.g., FEM100) without using extra components (e.g., attenuators) to adjust the power level of the coupled signal or frequency combiner components (e.g., multiplexers) to couple multiple output signals. Similarly, the RF source (e.g., power amplifier module 110) that provides the input signal to the directional coupler 300 can operate at a constant output power level over frequency, improving the efficiency of the power amplifier module 110 and / or the power consumption of the FEM 100. In addition, the compact footprint of the directional coupler 300 may allow for a reduction in the footprint or package size of the FEM 100.

[0037] In some examples, the first and second termination impedances 314a, 314b include at least one RLC (resistive-inductive-capacitive) circuit comprising one or more resistive, inductive, or capacitive elements, or a combination thereof. For example, Figure 5 is a schematic diagram of a directional coupler 500 relating to the aspect described herein. The directional coupler 500 corresponds to the directional coupler 300 of Figure 3, having first and second termination impedances 514a, 514b configured as an RLC circuit.

[0038] In one example, the first termination impedance 514a is configured to provide a termination impedance optimized for a first frequency (e.g., 900 MHz), and the second termination impedance 514b is configured to provide a termination impedance optimized for a second frequency (e.g., 2.7 GHz). In some examples, the first termination impedance 514a may provide an optimized termination impedance by matching the characteristic impedance of the coupled transmission line 312 at the first frequency. Similarly, the second termination impedance 514b may provide an optimized termination impedance by matching the characteristic impedance of the coupled transmission line 312 (or the L2 portion of the coupled transmission line 312) at the second frequency.

[0039] In some examples, the first and second termination impedances 514a, 514b may be permanently connected to the coupled transmission line 312. For example, the first and second termination impedances 514a, 514b may be directly connected to the coupled transmission line 312 via a transmission line or conductive wire (e.g., a microstrip, strip line, coplanar line, etc.). Although the first and second termination impedances 514a, 514b are described above as RLC circuits permanently connected to the coupled transmission line 312, in other examples the termination impedances may be configured differently and / or connected to the coupled transmission line 312 in different ways.

[0040] Figure 6 shows several termination impedance configurations relating to the plane described herein. In some examples, the first termination impedance 314a and / or the second termination impedance 314b of the directional coupler 300 in Figure 3 may be configured as any of the termination impedance configurations shown in Figure 6.

[0041] In one example, the first termination impedance configuration 602 includes an RLC circuit (or network) 604 and a switch 606. Similar to the first and second termination impedances 514a, 514b in Figure 5, the RLC circuit 604 may be configured to match the characteristic impedance of the coupled transmission line 312 at a specific frequency (e.g., a first frequency or a second frequency). In some examples, the switch 606 can be operated to selectively connect or disconnect the RLC circuit 604 from the transmission line 312. For example, if the first termination impedance 314a is configured as the first termination impedance configuration 602, the switch 606 may be operated to connect the RLC circuit 604 to the first termination port 308a when a radio frequency signal having a first frequency is received at the input port 302 of the directional coupler 300. Similarly, switch 606 may be operated to disconnect the RLC circuit 604 from the first termination port 308a when a radio frequency signal having a second frequency is received at the input port 302 of the directional coupler 300.

[0042] In one example, the second termination impedance configuration 612 includes an adjustable RLC circuit (or network) 614. In some examples, the adjustable RLC circuit 614 includes one or more tuneable resistive, inductive, or capacitive elements, or a combination thereof. In some examples, the adjustable RLC circuit 614 may be tuned / tuned based on the operating mode of the directional coupler 300. For example, if the first termination impedance 314a is configured as the termination impedance configuration 612, the adjustable RLC circuit 614 may be tuned to provide a first termination impedance optimized for a specific frequency (e.g., a first frequency) during the first operating mode. Similarly, during the second operating mode, the adjustable RLC circuit 614 may be tuned to provide a second termination impedance optimized for a different frequency (e.g., a third frequency). In some examples, the termination impedance configuration 612 may be permanently connected to the coupled transmission line 312. However, in other examples, the termination impedance configuration 612 may be selectively connected to the coupled transmission line 312 (for example, via a switch).

[0043] In one example, the third termination impedance configuration 622 is configured as an adjustable termination circuit. In some examples, the termination impedance configuration 622 includes one or more switches controlled to select different combinations of termination impedance values. Similar to the termination impedance configuration 612, the termination impedance configuration 622 may be adjusted / tuned based on the operating mode of the directional coupler 300. An example of such an adjustable termination circuit is described in U.S. Patent No. 9,614,269 to Srirattana et al., entitled “RF COUPLER WITH ADJUSTABLE TERMINATION IMPEDANCE,” which is incorporated herein by reference.

[0044] In one example, the fourth termination impedance configuration 632 includes a filter 634 and a termination impedance 636. In some examples, the filter 634 is configured to provide signals of a specific frequency (or frequency band) to the termination impedance 636. For example, if the first termination impedance 314a is configured as the termination impedance configuration 632, the filter 634 may be configured to allow radio frequency signals of the first frequency while blocking radio frequency signals of a different frequency (e.g., a second frequency). In some examples, the filter 634 can improve isolation between termination ports (e.g., first and second termination ports 308a, 308b). The filter 634 may be configured as a low-pass filter, a high-pass filter, or a band-pass filter. In some examples, the filter 634 may be permanently connected to the coupled transmission line 312. However, in other examples, the filter 634 may be selectively connected to the coupled transmission line 312 (e.g., via a switch). The termination impedance 636 may be configured as a fixed or adjustable termination impedance. For example, the termination impedance 636 may be configured as one of the termination impedance configurations 602, 612, and 622, or any other type of termination impedance.

[0045] As previously mentioned, the directional coupler 300 can be arranged in a compact layout. For example, Figure 7 shows a layout 700 of the directional coupler 300 according to the view described herein. As shown, the main transmission line 310 and the coupled transmission line 312 can be arranged in a compact layout. In one example, the main transmission line 310 is routed between the input port 302 and the output port 304 on the first layer. The first portion of the coupled transmission line 312 (i.e., L2) is routed between the coupled port 306 and the second termination port 308b on the first layer. Although not shown, the second portion of the coupled transmission line 312 (i.e., the difference between L1 and L2) is routed between the first termination port 308a and the second termination port 308b on the second layer. In some examples, the first and second portions of the coupled transmission line 312 may be connected using a conductive via structure. In other examples, the coupler 300 may be arranged or routed differently. For example, the entire coupled transmission line 312 may be routed on the same layer (e.g., a first layer or a second layer).

[0046] Although the directional coupler 300 is described above as having a unidirectional configuration with two termination ports, it should be understood that the directional coupler 300 can be configured in different ways. For example, the directional coupler 300 can be configured as a bidirectional coupler and / or may include three or more termination ports.

[0047] Figure 8 is a schematic diagram of a bidirectional coupler 800 relating to the aspect described herein. As shown in the figure, the bidirectional coupler 800 includes an input port 802, an output port 804, a forward coupling port 806a, a reverse coupling port 806b, a first forward termination port 808a, a second forward termination port 808b, a first reverse termination port 808c, a second reverse termination port 808d, a main transmission line 810, a coupled transmission line 812, a first forward termination impedance 814a, a second forward termination impedance 814b, a first reverse termination impedance 814c, a second reverse termination impedance 814d, a first switch 816a, a second switch 816b, a third switch 816c, and a fourth switch 816d. Switches 816a to 816d are operated to selectively couple the termination impedances 814a to 814d to the coupled transmission line 812.

[0048] In some examples, when a radio frequency signal is applied to the input port 802 of the main transmission line 810, this signal is output via the output port 804 of the main transmission line 810, and the coupling signal is provided to the forward coupling port 806a of the coupling transmission line 812. Similarly, when a radio frequency signal is applied to the output port 804 of the main transmission line 810, this signal is output via the input port 802 of the main transmission line 810, and the coupling signal is provided to the reverse coupling port 806b of the coupling transmission line 812.

[0049] In one example, the termination impedances 814a to 814d are optimized (i.e., tuned) for a specific frequency (or frequency band). For example, the first forward termination impedance 814a and the first reverse termination impedance 814c may be optimized for a first frequency, and the second forward termination impedance 814b and the second reverse termination impedance 814d may be optimized for a second frequency. Each of the termination impedances 814a to 814d may be configured as a fixed or adjustable termination impedance. For example, each of the termination impedances 814a to 814d may be configured as one of the termination impedance configurations 602, 612, and 622 in Figure 6, or as any other type of termination impedance.

[0050] As previously mentioned, switches 816a to 816d may be operated to selectively couple the termination impedances 814a to 814d to the coupled transmission line 312. In some examples, the bidirectional coupler 800 may be configured to operate in different operating modes corresponding to the direction of operation (i.e., forward or reverse).

[0051] For example, in forward operation mode, the third switch 816c may be controlled to couple the forward coupling port 806a to the coupling transmission line 812. The first switch 816a may be controlled to couple the first forward termination impedance 814a to the first forward termination port 808a, and the second switch 816b may be controlled to couple the second forward termination impedance 814b to the second forward termination port 808b. Similarly, in reverse operation mode, the first switch 816a may be controlled to couple the reverse coupling port 806b to the coupling transmission line 312. The third switch 816c may be controlled to couple the first reverse termination impedance 814c to the first reverse termination port 808c, and the fourth switch 816d may be controlled to couple the second reverse termination impedance 814d to the second reverse termination port 808d. In some examples, switches 816a to 816d can be operated or controlled simultaneously (i.e., together). However, in other examples, switches 816a to 816d can be operated or controlled individually.

[0052] Similar to the directional coupler 300 in Figure 3, the bidirectional coupler 800 can achieve desired performance at each of the first and second frequencies by providing optimized coupling coefficients for each of the first and second frequencies. In some examples, the bidirectional coupler 800 allows multiple signals having different frequencies to be coupled simultaneously (e.g., carrier aggregation). Therefore, the bidirectional coupler 800 may be integrated into a device (e.g., FEM100) without the use of extra components for adjusting the power level of the coupled signals (e.g., attenuators) or frequency combiner components for coupling multiple output signals (e.g., multiplexers). Similarly, an RF source (e.g., power amplifier module 110) providing an input signal to the bidirectional coupler 800 can operate at a constant output power level across frequency, improving the efficiency of the power amplifier module 110 and / or the power consumption of the FEM100. In addition, the compact footprint of the bidirectional coupler 800 may allow for a reduction in the footprint or package size of the FEM100.

[0053] Figure 9 is a schematic diagram of a bidirectional coupler 900 relating to the aspect described herein. In one example, the bidirectional coupler 900 is substantially the same as the bidirectional coupler 800 of Figure 8, except that the bidirectional coupler 900 is configured to use a common termination impedance for both the forward and reverse operating modes. Thus, the number of different termination impedances can be reduced compared to the bidirectional coupler 800 of Figure 8. As shown in the figure, the bidirectional coupler 900 includes an input port 902, an output port 904, a forward coupling port 906a, a reverse coupling port 906b, a first forward termination port 908a, a second forward termination port 908b, a first reverse termination port 908c, a second reverse termination port 908d, a main transmission line 910, a coupled transmission line 912, a first termination impedance 914a, a second termination impedance 914b, a first switch 916a, a second switch 916b, a third switch 916c, and a fourth switch 916d. Switches 916a to 916d are operated to selectively couple termination impedances 914a and 914b to the coupled transmission line 912.

[0054] In some examples, when a radio frequency signal is supplied to the input port 902 of the main transmission line 910, this signal is output via the output port 904 of the main transmission line 910, and the coupling signal is supplied to the forward coupling port 906a of the coupling transmission line 912. Similarly, when a radio frequency signal is supplied to the output port 904 of the main transmission line 910, this signal is output via the input port 902 of the main transmission line 910, and the coupling signal is supplied to the reverse coupling port 906b of the coupling transmission line 912.

[0055] In one example, the termination impedances 914a and 914b are optimized (i.e., tuned) to a specific frequency (or frequency band). For example, the first termination impedance 914a may be optimized to a first frequency, and the second termination impedance 914b may be optimized to a second frequency. Each of the termination impedances 914a and 914b may be configured as a fixed or adjustable termination impedance. For example, each of the termination impedances 914a and 914b may be configured as one of the termination impedance configurations 602, 612, and 622 in Figure 6, or any other type of termination impedance.

[0056] As previously mentioned, switches 916a to 916d can be operated to selectively couple the termination impedances 914a and 914b to the coupled transmission line 912. In some examples, the bidirectional coupler 900 may be configured to operate in different operating modes corresponding to the direction of operation (i.e., forward or reverse).

[0057] For example, in forward operation mode, the third switch 916c may be controlled to couple the forward coupling port 906a to the coupling transmission line 912. The first switch 916a may be controlled to couple the first termination impedance 914a to the first forward termination port 908a, and the second switch 916b may be controlled to couple the second termination impedance 914b to the second forward termination port 908b. Similarly, in reverse operation mode, the first switch 916a may be controlled to couple the reverse coupling port 906b to the coupling transmission line 912. The third switch 916c may be controlled to couple the first termination impedance 914a to the first reverse termination port 908c, and the fourth switch 916d may be controlled to couple the second termination impedance 914b to the second reverse termination port 908d. In some examples, switches 916a to 916d can be operated or controlled simultaneously (i.e., together). However, in other examples, switches 916a to 916d can be operated or controlled individually.

[0058] Similar to the directional coupler 300 in Figure 3, the bidirectional coupler 900 can achieve desired performance at each of the first and second frequencies by providing optimized coupling coefficients for each of the first and second frequencies. In some examples, the bidirectional coupler 900 allows multiple signals having different frequencies to be coupled simultaneously (e.g., carrier aggregation). Therefore, the bidirectional coupler 900 may be integrated into a device (e.g., FEM100) without the use of extra components for adjusting the power level of the coupled signals (e.g., attenuators) or frequency combiner components for coupling multiple output signals (e.g., multiplexers). Similarly, an RF source (e.g., power amplifier module 110) providing an input signal to the bidirectional coupler 900 can operate at a constant output power level over frequency, improving the efficiency of the power amplifier module 110 and / or the power consumption of the FEM100. In addition, since the bidirectional coupler 900 is configured with a common termination impedance, the compact footprint of the bidirectional coupler 900 may allow for a further reduction in the footprint or package size of the FEM100.

[0059] In the above description, couplers 300, 500, 800, and 900 were explained as being optimized for two signal frequencies (i.e., the first and second frequencies), but it should be understood that couplers can be optimized for three or more signal frequencies.

[0060] Figure 10 is a schematic diagram of a bidirectional coupler 1000 relating to the aspect described herein. In one example, the bidirectional coupler 1000 is substantially the same as the bidirectional coupler 800 in Figure 8, except that the bidirectional coupler 1000 is configured to support three signal frequencies (or frequency bands). As shown, the bidirectional coupler 1000 comprises an input port 1002, an output port 1004, a forward coupling port 1006a, a reverse coupling port 1006b, a first forward termination port 1008a, a second forward termination port 1008b, a third forward termination port 1008c, a first reverse termination port 1008d, a second reverse termination port 1008e, a third reverse termination port 1008f, a main transmission line 1010, a coupling transmission line 1012, and a first forward termination It includes an impedance 1014a, a second forward termination impedance 1014b, a third forward termination impedance 1014c, a first reverse termination impedance 1014d, a second reverse termination impedance 1014e, a third reverse termination impedance 1014f, a first switch 1016a, a second switch 1016b, a third switch 1016c, a fourth switch 1016d, a fifth switch 1016e, and a sixth switch 1016f. Switches 1016a to 1016f are operated to selectively couple the termination impedances 1014a to 1014f to the coupled transmission line 1012.

[0061] In some examples, when a radio frequency signal is applied to the input port 1002 of the main transmission line 1010, this signal is output via the output port 1004 of the main transmission line 1010, and the coupling signal is provided to the forward coupling port 1006a of the coupling transmission line 1012. Similarly, when a radio frequency signal is applied to the output port 1004 of the main transmission line 1010, this signal is output via the input port 1002 of the main transmission line 1010, and the coupling signal is provided to the reverse coupling port 1006b of the coupling transmission line 1012.

[0062] In one example, the termination impedances 1014a to 1014f are optimized (i.e., tuned) to a specific frequency (or frequency band). For example, the first forward termination impedance 1014a and the first reverse termination impedance 1014d may be optimized to a first frequency, the second forward termination impedance 1014b and the second reverse termination impedance 1014e may be optimized to a second frequency, and the third forward termination impedance 1014c and the third reverse termination impedance 1014f may be optimized to a third frequency. Each of the termination impedances 1014a to 1014f may be configured as a fixed or adjustable termination impedance. For example, each of the termination impedances 1014a to 1014f may be configured as one of the termination impedance configurations 602, 612, and 622 in Figure 6, or as any other type of termination impedance.

[0063] As previously mentioned, switches 1016a to 1016f can be operated to selectively couple termination impedances 1014a to 1014f to the coupled transmission line 1012. In some examples, the bidirectional coupler 1000 may be configured to operate in different operating modes corresponding to the direction of operation (i.e., forward or reverse).

[0064] For example, in forward operation mode, the fourth switch 1016d may be controlled to couple the forward coupling port 1006a to the coupling transmission line 1012. The first switch 1016a may be controlled to couple the first forward termination impedance 1014a to the first forward termination port 1008a, the second switch 1016b may be controlled to couple the second forward termination impedance 1014b to the second forward termination port 1008b, and the third switch 1016c may be controlled to couple the third forward termination impedance 1014c to the third forward termination port 1008c. Similarly, in reverse operation mode, the first switch 1016a may be controlled to couple the reverse coupling port 1006b to the coupling transmission line 1012. The fourth switch 1016d may be controlled to couple the first reverse termination impedance 1014d to the first reverse termination port 1008d, the fifth switch 1016e may be controlled to couple the second reverse termination impedance 1014e to the second reverse termination port 1008e, and the sixth switch 1016f may be controlled to couple the third reverse termination impedance 1014f to the third reverse termination port 1008f. In some examples, switches 1016a to 1016d can be operated or controlled simultaneously (i.e., together). However, in other examples, switches 1016a to 1016d can be operated or controlled individually.

[0065] In one example, the bidirectional coupler 1000 can achieve desired performance at each of the first, second, and third frequencies by providing optimized coupling coefficients for each of the first, second, and third frequencies. In some examples, the bidirectional coupler 1000 allows multiple signals having different frequencies to be coupled simultaneously (e.g., carrier aggregation). Therefore, the bidirectional coupler 1000 may be integrated into a device (e.g., FEM 100) without the use of extra components for adjusting the power level of the coupled signals (e.g., attenuators) or frequency combiner components for coupling multiple output signals (e.g., multiplexers). Similarly, an RF source (e.g., a power amplifier module 110) providing an input signal to the bidirectional coupler 1000 can operate at a constant output power level across frequency, improving the efficiency of the power amplifier module 110 and / or the power consumption of the FEM 100. In addition, the compact footprint of the bidirectional coupler 1000 may allow for a reduction in the footprint or package size of the FEM 100.

[0066] Figure 11 is a schematic diagram of a bidirectional coupler 1100 relating to the aspect described herein. In one example, the bidirectional coupler 1100 is substantially the same as the bidirectional coupler 1000 of Figure 10, except that the bidirectional coupler 1100 is configured using a reduced number of switches. As shown, the bidirectional coupler 1100 comprises an input port 1102, an output port 1104, a forward coupling port 1106a, a reverse coupling port 1106b, a first forward termination port 1108a, a second forward termination port 1108b, a first reverse termination port 1108c, a second reverse termination port 1108d, a main transmission line 1110, a coupling transmission line 1112, and a first forward termination impedance It includes a dance 1114a, a second forward termination impedance 1114b, a third forward termination impedance 1114c, a first reverse termination impedance 1114d, a second reverse termination impedance 1114e, a third reverse termination impedance 1114f, a first switch 1116a, a second switch 1116b, a third switch 1116c, and a fourth switch 1116d. Switches 1116a to 1116d are operated to selectively couple the termination impedances 1114a to 1114f to the coupled transmission line 1112.

[0067] In some examples, when a radio frequency signal is applied to the input port 1102 of the main transmission line 1110, this signal is output via the output port 1104 of the main transmission line 1110, and the coupling signal is provided to the forward coupling port 1106a of the coupling transmission line 1112. Similarly, when a radio frequency signal is applied to the output port 1104 of the main transmission line 1110, this signal is output via the input port 1102 of the main transmission line 1110, and the coupling signal is provided to the reverse coupling port 1106b of the coupling transmission line 1112.

[0068] In one example, the termination impedances 1114a to 1114f are optimized (i.e., tuned) to a specific frequency (or frequency band). For example, the first forward termination impedance 1114a and the first reverse termination impedance 1114d may be optimized to a first frequency, the second forward termination impedance 1114b and the second reverse termination impedance 1114e may be optimized to a second frequency, and the third forward termination impedance 1114c and the third reverse termination impedance 1114f may be optimized to a third frequency. Each of the termination impedances 1114a to 1114f may be configured as a fixed or adjustable termination impedance. For example, each of the termination impedances 1114a to 1114f may be configured as one of the termination impedance configurations 602, 612, and 622 in Figure 6, or any other type of termination impedance.

[0069] As previously mentioned, switches 1116a to 1116d may be operated to selectively couple termination impedances 1114a to 1114f to the coupled transmission line 1112. In some examples, the bidirectional coupler 1100 may be configured to operate in different operating modes corresponding to the direction of operation (i.e., forward or reverse).

[0070] For example, in forward operation mode, the third switch 1116c may be controlled to couple the forward coupling port 1106a to the coupling transmission line 1112. The first switch 1116a may be controlled to couple the first forward termination impedance 1114a to the first forward termination port 1108a, and the second switch 1116b may be controlled to couple one of the second and third forward termination impedances 1114b, 1114c to the second forward termination port 1108b. Similarly, in reverse operation mode, the first switch 1116a may be controlled to couple the reverse coupling port 1106b to the coupling transmission line 1112. The third switch 1116c may be controlled to couple the first reverse termination impedance 1114d to the first reverse termination port 1108c, and the fourth switch 1116d may be controlled to couple one of the second and third reverse termination impedances 1114e, 1114f to the second reverse termination port 1108d. In some embodiments, switches 1116a to 1116d can be operated or controlled simultaneously (i.e., together). However, in other embodiments, switches 1116a to 1116d can be operated or controlled individually.

[0071] In one example, the bidirectional coupler 1100 can achieve desired performance at each of the first, second, and third frequencies by providing optimized coupling coefficients for each of the first, second, and third frequencies. In some examples, the bidirectional coupler 1100 allows multiple signals having different frequencies to be coupled simultaneously (e.g., carrier aggregation). Therefore, the bidirectional coupler 1100 may be integrated into a device (e.g., FEM 100) without the use of extra components (e.g., attenuators) for adjusting the power level of the coupled signals or frequency combiner components (e.g., multiplexers) for coupling multiple output signals. Similarly, an RF source (e.g., a power amplifier module 110) providing an input signal to the bidirectional coupler 1100 can operate at a constant output power level across frequency, improving the efficiency of the power amplifier module 110 and / or the power consumption of the FEM 100. In addition, since the bidirectional coupler 1100 is configured using a reduced number of switches, the compact footprint of the bidirectional coupler 1100 may allow for a further reduction in the footprint or package size of the FEM100.

[0072] Figure 12 is a schematic diagram of a bidirectional coupler 1200 relating to the aspect described herein. In one example, the bidirectional coupler 1200 is substantially the same as the bidirectional coupler 1000 of Figure 10, except that the bidirectional coupler 1200 is configured to use a common termination impedance for both the forward and reverse operating modes. As shown in the figure, the bidirectional coupler 1200 includes an input port 1202, an output port 1204, a forward coupling port 1206a, a reverse coupling port 1206b, a first forward termination port 1208a, a second forward termination port 1208b, a first reverse termination port 1208c, a second reverse termination port 1208d, a main transmission line 1210, a coupled transmission line 1212, a first termination impedance 1214a, a second termination impedance 1214b, a third termination impedance 1214c, a first switch 1216a, a second switch 1216b, a third switch 1216c, and a fourth switch 1216d. Switches 1216a to 1216d are operated to selectively couple termination impedances 1214a to 1214c to the coupled transmission line 1212.

[0073] In some examples, when a radio frequency signal is applied to the input port 1202 of the main transmission line 1210, this signal is output via the output port 1204 of the main transmission line 1210, and the coupling signal is provided to the forward coupling port 1206a of the coupling transmission line 1212. Similarly, when a radio frequency signal is applied to the output port 1204 of the main transmission line 1210, this signal is output via the input port 1202 of the main transmission line 1210, and the coupling signal is provided to the reverse coupling port 1206b of the coupling transmission line 1212.

[0074] In one example, the termination impedances 1214a to 1214c are optimized (i.e., tuned) to a specific frequency (or frequency band). For example, the first termination impedance 1214a may be optimized to a first frequency, the second termination impedance 1214b may be optimized to a second frequency, and the third termination impedance 1214c may be optimized to a third frequency. Each of the termination impedances 1214a to 1214c may be configured as a fixed or adjustable termination impedance. For example, each of the termination impedances 1214a to 1214c may be configured as one of the termination impedance configurations 602, 612, and 622 in Figure 6, or as any other type of termination impedance.

[0075] As previously mentioned, switches 1216a to 1216d can be operated to selectively couple termination impedances 1214a to 1214c to the coupled transmission line 1212. In some examples, the bidirectional coupler 1200 may be configured to operate in different operating modes corresponding to the direction of operation (i.e., forward or reverse).

[0076] For example, in forward operation mode, the third switch 1216c may be controlled to couple the forward coupling port 1206a to the coupling transmission line 1212. The first switch 1216a may be controlled to couple the first termination impedance 1214a to the first forward termination port 1208a, and the second switch 1216b may be controlled to couple either the second termination impedance 1214b or the third termination impedance 1214c to the second forward termination port 1208b. Similarly, in reverse operation mode, the first switch 1216a may be controlled to couple the reverse coupling port 1206b to the coupling transmission line 1212. The third switch 1216c may be controlled to couple the first termination impedance 1214a to the first reverse termination port 1208c, and the fourth switch 1216d may be controlled to couple either the second termination impedance 1214b or the third termination impedance 1214c to the second reverse termination port 1208d. In some examples, switches 1216a to 1216d can be operated or controlled simultaneously (i.e., together). However, in other examples, switches 1216a to 1216d can be operated or controlled individually.

[0077] In one example, the bidirectional coupler 1200 can achieve desired performance at each of the first, second, and third frequencies by providing optimized coupling coefficients for each of the first, second, and third frequencies. In some examples, the bidirectional coupler 1200 allows multiple signals having different frequencies to be coupled simultaneously (e.g., carrier aggregation). Therefore, the bidirectional coupler 1200 may be integrated into a device (e.g., FEM100) without the use of extra components (e.g., attenuators) for adjusting the power level of the coupled signals or frequency combiner components (e.g., multiplexers) for coupling multiple output signals. Similarly, an RF source (e.g., a power amplifier module 110) providing an input signal to the bidirectional coupler 1200 can operate at a constant output power level across frequency, improving the efficiency of the power amplifier module 110 and / or the power consumption of the FEM100. In addition, since the bidirectional coupler 1200 is configured with a common termination impedance, the compact footprint of the bidirectional coupler 1200 may allow for a further reduction in the footprint or package size of the FEM100.

[0078] As previously mentioned, the switches shown in Figures 8 to 12 can be controlled / operated simultaneously or independently. For example, when the bidirectional coupler 1000 in Figure 10 is operating in forward operation mode, switches 1016a, 1016b, and 1016c may be controlled simultaneously to couple the forward termination impedances 1014a, 1014b, and 1014c to the coupling transmission line 1012. However, if the frequency of the input signal received at input port 1002 is known, switches 1016a to 1016c may be operated differently. For example, if the input signal corresponds to a first frequency, the first switch 1016a may be controlled to couple the first forward termination impedance 1014a to the coupling transmission line 1012, while the second and third switches 1016b and 1016c may remain open or disconnected from the coupling transmission line 1012. Similarly, when the input signal corresponds to a second frequency, the second switch 1016b may be controlled to couple the second forward termination impedance 1014b to the coupled transmission line 1012, and the first and third switches 1016a and 1016c may remain open or disconnected from the coupled transmission line 1012. Switches 1014d to 1014f may be controlled similarly during reverse operation mode. Any of the switches shown in Figures 8 to 12 can be operated or controlled in a similar manner.

[0079] As shown in Figures 8 to 12, the arrangement (or position) of the termination impedances is symmetrical along the length of the coupled transmission line such that the forward coupling coefficient is substantially the same as the reverse coupling coefficient. For example, as shown in Figure 10, the first forward termination impedance 1014a and the first reverse termination impedance 1014d are arranged symmetrically along the coupled transmission line 1012 such that the coupling coefficient for a first frequency is substantially the same in both the forward and reverse directions. Similarly, the second forward termination impedance 1014b and the second reverse termination impedance 1014e are arranged symmetrically along the coupled transmission line 1012 such that the coupling coefficient for a second frequency is substantially the same in both the forward and reverse directions. Although the arrangement (or position) of the termination impedances is shown symmetrically along the length of the coupled transmission line in Figures 8 to 12, it should be understood that in other examples, the termination impedances may be arranged differently. For example, the termination impedances may be arranged or set asymmetrically to provide different coupling coefficients in the forward and reverse directions.

[0080] It should be understood that any of the above couplers can be used for a variety of wireless applications. For example, each coupler may be configured for use in wireless local area networks (WLANs), ultra-wideband (UWB), wireless personal area networks (WPANs), 4G cellular, and LTE cellular applications.

[0081] In some examples, switches included in any of the couplers (e.g., switches 816a-816b of bidirectional coupler 800) may include gallium nitride (GaN), gallium arsenide (GaAs), or silicon germanium (SiGe) transistors. In some 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 (CMOSs). In some examples, any of the couplers, or one or more components of the couplers, may be fabricated using silicon-on-insulator (SOI) technology.

[0082] Embodiments of the coupling described herein can be conveniently used in a variety of electronic devices. Examples of electronic devices may include, but are not limited to, consumer electronic products, components of consumer electronic products, electronic test equipment, and cellular communication infrastructure such as base stations. 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-book readers, wearable computers such as smartwatches, personal digital assistants (PDAs), electrical appliances such as microwave ovens and refrigerators, automobiles, stereo systems, digital music players such as DVD players, CD players, and MP3 players, radios, camcorders, cameras, digital cameras, portable memory chips, medical monitoring devices, automotive electronic systems such as automotive electronic systems and avionics electronic systems, peripherals, watches, and clocks. Furthermore, electronic devices may include unfinished products.

[0083] As previously stated, improved signal couplers are provided herein. In at least one embodiment, the coupler includes a plurality of terminations arranged to provide different coupling coefficients optimized for a range of signal frequencies. In some examples, each termination is connected to the coupling line of the coupler at different locations to provide different coupling coefficients. In some examples, the plurality of terminations are configured to maintain a substantially constant coupling power level while minimizing insertion loss over a range of signal frequencies.

[0084] While several aspects of at least one embodiment have been described, it should be understood that various changes, modifications, and improvements will readily come to mind for those skilled in the art. Such changes, modifications, and improvements are intended to be part of this disclosure and within the scope of the invention. Accordingly, the foregoing description and drawings are merely illustrative, and the scope of the invention should be determined from the appropriate configuration of the appended claims and their equivalents.

Claims

1. 1. A radio frequency signal combiner, comprising: An input port; An output port; a main transmission line extending between the input port and the output port; a continuous coupled transmission line electromagnetically coupled to the main transmission line; at least one coupled port coupled to the continuous coupled transmission line; and a plurality of termination ports selectively connected to the continuous coupled transmission line to provide a plurality of coupling coefficients corresponding to a plurality of signal frequencies, wherein at least one of the plurality of termination ports is configured to selectively couple to the continuous coupled transmission line at a location between a first end and a second end of the continuous coupled transmission line, and at least one different of the plurality of termination ports is configured to selectively couple to the continuous coupled transmission line at a location different from the at least one termination port, wherein the plurality of termination ports are configured to selectively couple to the continuous coupled transmission line, and at least two termination ports have different termination impedances and are configured to be simultaneously selectively coupled to the continuous coupled transmission line.

2. 10. The radio frequency signal coupler of claim 1, further comprising a plurality of termination impedances coupled to the plurality of termination ports.

3. The radio frequency signal coupler of claim 2 , further comprising a plurality of switches configured to selectively connect the plurality of termination impedances to the plurality of termination ports.

4. 4. The radio frequency signal coupler of claim 3, wherein switches of the plurality of switches are symmetrically coupled to the continuous coupled transmission line and configured to selectively couple impedances of the plurality of termination impedances based on a radio frequency signal being received at the input port or the output port.

5. The radio frequency signal coupler of claim 2 , wherein each termination impedance of the plurality of termination impedances comprises a fixed impedance and / or a tunable impedance.

6. 3. The radio frequency signal coupler of claim 2, wherein a first termination impedance of the plurality of termination impedances is coupled to a first termination port of the plurality of termination ports and a second termination impedance of the plurality of termination impedances is coupled to a second termination port of the plurality of termination ports.

7. 7. The radio frequency signal coupler of claim 6, wherein the first termination impedance is tuned to a first signal frequency of the plurality of signal frequencies and the second termination impedance is tuned to a second signal frequency of the plurality of signal frequencies.

8. 8. The radio frequency signal coupler of claim 7, wherein the first termination port is connected to the continuous coupled transmission line at a first location to provide a first coupling coefficient corresponding to the first signal frequency, and the second termination port is connected to the continuous coupled transmission line at a second location to provide a second coupling coefficient corresponding to the second signal frequency.

9. 9. The radio frequency signal coupler of claim 8, wherein the first coupling coefficient corresponds to a first length of the continuous coupled transmission line between the first termination port and the at least one coupled port, and the second coupling coefficient corresponds to a second length of the continuous coupled transmission line between the second termination port and the at least one coupled port.

10. 9. The radio frequency signal coupler of claim 8, wherein the first coupling coefficient is selected to provide a desired level of insertion loss at the first signal frequency and the second coupling coefficient is selected to provide a desired level of insertion loss at the second signal frequency.

11. 11. The radio frequency signal coupler of claim 10, wherein the first coupling coefficient at the first signal frequency is substantially similar to the second coupling coefficient at the second signal frequency.

12. 11. The radio frequency signal coupler of claim 10, wherein the radio frequency signal coupler is configured to minimize insertion loss between the input port and the output port at the first and second signal frequencies.

13. 13. The radio frequency signal combiner of claim 12, wherein the at least one coupled port includes a first coupled port configured to provide a first coupled signal when an input radio frequency signal is received at the input port.

14. 14. The radio frequency signal combiner of claim 13, wherein the radio frequency signal combiner is configured to maintain a substantially constant power level of the first combined signal at the first and second signal frequencies.

15. 15. The radio frequency signal combiner of claim 14, wherein the at least one coupled port includes a second coupled port configured to provide a second coupled signal when an input radio frequency signal is received at the output port.

16. 16. The radio frequency signal combiner of claim 15, wherein the radio frequency signal combiner is configured to maintain a substantially constant power level of the second combined signal at the first and second signal frequencies.

17. A radio frequency signal combiner, comprising: An input port; An output port; a main transmission line extending between the input port and the output port; a continuous coupled transmission line electromagnetically coupled to the main transmission line; at least one coupled port coupled to the continuous coupled transmission line; a plurality of termination ports selectively connected to the continuous coupled transmission line to provide a plurality of coupling coefficients corresponding to a plurality of signal frequencies, at least one termination port of the plurality of termination ports configured to selectively couple to the continuous coupled transmission line at a location between a first end and a second end of the continuous coupled transmission line, and at least one different termination port of the plurality of termination ports configured to selectively couple to the continuous coupled transmission line at a location different from the at least one termination port; the radio frequency signal combiner is configured to maintain a substantially constant power level of a first combined signal at a first signal frequency of the plurality of signal frequencies and at a second signal frequency of the plurality of signal frequencies, and configured to maintain a substantially constant power level of a second combined signal at the first signal frequency and at the second signal frequency.

18. 1. A method for reducing insertion loss in a radio frequency coupler, the method comprising: The method includes receiving a radio frequency (RF) signal on a first transmission line that is electromagnetically coupled to a continuous second transmission line, the RF signal having a frequency that is one of a first frequency and a second frequency different from the first frequency, the method further comprising: inducing an induced RF signal on the continuous second transmission line based on the RF signal, the induced RF signal having one of the first frequency and the second frequency corresponding to the frequency of the RF signal, the method further comprising: terminating the induced RF signal having the first frequency at a first location along a length of the continuous second transmission line to provide a first coupled signal having a first coupling coefficient; and terminating the induced RF signal having the second frequency at a second location along the continuous second transmission line to provide a second coupled signal having a second coupling coefficient that is substantially identical to the first coupling coefficient.

19. 20. The method of claim 18, further comprising adjusting at least one impedance of a plurality of impedances coupled to the continuous second transmission line to change the coupling coefficient of the first transmission line and the continuous second transmission line.

20. 20. The method of claim 19, wherein the continuous second transmission line has one or more switches coupled to the plurality of impedances, the method further comprising selectively switching the switches on or off based on at least one of a direction or a frequency of the RF signal.

21. 20. The method of claim 18, further comprising selecting the first and second locations to maximize directivity at the first and second frequencies, to maximize isolation at the first and second frequencies, to minimize the first coupling coefficient at the first frequency, and to minimize the second coupling coefficient at the second frequency.

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