PATENT DOCUMENT

Publication Number: US-11791973-B2
Application Number: US-202017031440-A
Country: US
Kind Code: B2

Title: Full-duplex electrical balanced duplexer

Abstract:
Embodiments disclosed herein relate to improving an available bandwidth for a transceiver of an electronic device and to reducing a footprint of an associated integrated circuit of the electronic device. To do so, an isolation circuit is disposed between a transmit circuit and a receive circuit. The isolation circuit has first and second signal paths. A first portion of the signal propagates along the first signal path and a second portion of the signal propagates along the second signal path. A non-reciprocal phase shifter is disposed on the first signal path to shift a phase of the first portion to match a phase of the second portion and improve isolation between the transmit circuit and the receive circuit. The phase-shifted first portion may be combined with the second portion to reduce or substantially eliminate an insertion loss caused by the isolation circuit.

Claims:
What is claimed is: 
     
       1. An electronic device for full duplex communications comprising:
 one or more antennas coupled to a first signal path and a second signal path; 
 a first balun coupling the first signal path to the second signal path; 
 transmitter circuitry directly coupled to a first side of the first balun; 
 receiver circuitry directly coupled to a center tap of a second side of the first balun opposite the transmitter circuitry, the first side of the first balun configured to inductively couple to the second side of the first balun; 
 a bidirectional phase shifter disposed on the first signal path between the one or more antennas and the first balun; and 
 a non-reciprocal phase shifter disposed on the second signal path between the one or more antennas and the first balun. 
 
     
     
       2. The electronic device of  claim 1 , comprising:
 a first integrated circuit comprising the first balun, the transmitter circuitry, the receiver circuitry, the bidirectional phase shifter, and the non-reciprocal phase shifter; and 
 a second integrated circuit coupled to the first integrated circuit via a single path. 
 
     
     
       3. The electronic device of  claim 1 , wherein the bidirectional phase shifter shifts a phase of a signal on the second signal path to correlate with a phase of a signal on the first signal path shifted by the non-reciprocal phase shifter. 
     
     
       4. The electronic device of  claim 1 , wherein the non-reciprocal phase shifter shifts a phase of a signal received by the one or more antennas by +90 degrees and shifts a phase of a signal from the transmitter circuitry by −90 degrees. 
     
     
       5. The electronic device of  claim 1 , wherein the non-reciprocal phase shifter comprises a plurality of capacitors disposed in parallel, and wherein each capacitor of the plurality of capacitors is disposed in series with at least two transistors of a plurality of transistors. 
     
     
       6. The electronic device of  claim 1 , wherein the bidirectional phase shifter comprises at least two capacitors disposed in parallel and an inductor coupled to and disposed between the at least two capacitors. 
     
     
       7. The electronic device of  claim 1 , comprising a combiner circuit coupled to the first signal path, the second signal path, and the one or more antennas. 
     
     
       8. The electronic device of  claim 7 , further comprising an impedance matching circuit coupled to the combiner circuit and configured to correlate an impedance of the one or more antennas to an impedance of the first balun. 
     
     
       9. The electronic device of  claim 7 , wherein the combiner circuit comprises at least one of a second balun, a Wilkinson power divider, a T-line junction, or a node. 
     
     
       10. The electronic device of  claim 7 , wherein the combiner circuit is configured to constructively combine a first transmission signal from the transmitter circuitry on the first signal path and a second transmission signal from the transmitter circuitry on the second signal path. 
     
     
       11. The electronic device of  claim 1 , wherein a first portion of a received signal on the first signal path and a second portion of the received signal on the second signal path are in-phase at the first balun, the first portion of the received signal and the second portion of the received signal being blocked from passing the first balun and entering the transmitter circuitry. 
     
     
       12. An electronic device comprising:
 one or more antennas; 
 a transmit circuit configured to transmit a transmission signal via the one or more antennas; 
 a receive circuit configured to receive a receive signal via the one or more antennas; 
 an isolation circuit coupled to the one or more antennas, the transmit circuit, and the receive circuit, the isolation circuit configured to isolate the transmit circuit from the receive signal and to isolate the receive circuit from the transmission signal, the isolation circuit configured to couple to the one or more antennas via a first signal path, and the isolation circuit configured to couple to the one or more antennas via a second signal path; 
 a non-reciprocal phase shifter disposed on the first signal path between the one or more antennas and the isolation circuit, the non-reciprocal phase shifter configured to shift a phase of a first portion of the transmission signal therethrough by a first phase amount to constructively combine with a second portion of the transmission signal on the second signal path and configured to shift a phase of a first portion of the receive signal therethrough by a second phase amount to constructively combine with a second portion of the receive signal on the second signal path; and 
 a bidirectional phase shifter disposed on the second signal path between the one or more antennas and the isolation circuit, the bidirectional phase shifter configured to shift a phase of the second portion of the transmission signal therethrough by a third phase amount to constructively combine with the first portion of the transmission signal and to shift a phase of the second portion of the receive signal therethrough by the third phase amount to constructively combine with the first portion of the receive signal. 
 
     
     
       13. The electronic device of  claim 12 , wherein the non-reciprocal phase shifter comprises a plurality of capacitors disposed in parallel, and wherein each capacitor of the plurality of capacitors is disposed in series with at least two transistors of a plurality of transistors. 
     
     
       14. The electronic device of  claim 12 , wherein the first phase amount is −90 degrees and the second phase amount is +90 degrees. 
     
     
       15. The electronic device of  claim 12 , wherein the third phase amount is +90 degrees. 
     
     
       16. The electronic device of  claim 12 , wherein the bidirectional phase shifter comprises at least two capacitors disposed in parallel and an inductor coupled to and disposed between the at least two capacitors. 
     
     
       17. An electronic device for full duplex communications, comprising:
 one or more antennas; 
 a transmitter configured to generate a transmission signal via the one or more antennas; 
 a receiver configured to receive a receive signal via the one or more antennas; and 
 isolation circuitry configured to isolate the transmitter from the receive signal and to isolate the receiver from the transmission signal, the isolation circuitry coupled to a first signal path and a second signal path; 
 a first phase shifter on the first signal path between the one or more antennas and the isolation circuitry, the first phase shifter configured to shift a phase of a first portion of the transmission signal on the first signal path to generate a shifted first portion of the transmission signal on the first signal path; 
 a second phase shifter on the second signal path between the one or more antennas and the isolation circuitry, the second phase shifter configured to shift a phase of a second portion of the transmission signal on the second signal path to generate a shifted second portion of the transmission signal on the second signal path; and 
 combiner circuitry configured to constructively combine the shifted first portion of the transmission signal on the first signal path and the shifted second portion of the transmission signal on the second signal path into a combined signal. 
 
     
     
       18. The electronic device of  claim 17 , wherein the first phase shifter comprises a non-reciprocal phase shifter. 
     
     
       19. The electronic device of  claim 18 , wherein the second phase shifter comprises a bidirectional phase shifter. 
     
     
       20. The electronic device of  claim 19 , wherein the first phase shifter is configured to shift a phase of a first portion of the receive signal on the first signal path to generate a shifted first portion of the receive signal on the first signal path, the second phase shifter is configured to shift a phase of a second portion of the receive signal on the second signal path to generate a shifted second portion of the receive signal on the second signal path, and the shifted first portion of the receive signal on the first signal path and the shifted second portion of the receive signal on the second signal path is configured to combine into a combined signal at the receiver.

Description:
BACKGROUND 
     The present disclosure generally relates to wireless communication systems and, more specifically, to isolating wireless signals between transmitters and receivers in wireless communication devices. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     In an electronic device, a transmitter and a receiver may each be coupled to an antenna to enable the electronic device to both transmit and receive wireless signals. Certain electronic devices may include isolation circuitry having an electrical balanced duplexer (EBD) that isolates the transmitter from received signals of a first frequency range, and the receiver from transmission signals of a second frequency range (e.g., thus implementing frequency division duplex (FDD) operations), thus reducing interference when communicating. In such electronic devices, an impedance tuner may be used to match the impedance of the antenna to increase effectiveness of this isolation. However, as indicated above, using the FDD duplexer may limit a bandwidth available for receiving signals and transmitting signals (e.g., to about 100 megahertz (MHz) for each operation) compared to a “true” full-duplex transceiver (e.g., one that enables transmitting and receiving wireless signals at the same time and over the same frequency range). For example, when using an FDD duplexer, a bandwidth for transmitting signals may be about 20 MHz and a bandwidth for receiving signals may also be about 20 MHz. 
     Further, utilizing an FDD duplexer transceiver requires at least two cables (e.g., one for transmitting signals at a first frequency range, another for receiving signals at a second frequency range). Utilizing two cables rather than a single cable to receive and transmit signals over the same frequency range takes up valuable space in the electronic device. As a result, the electronic device having two cables may be larger in size or prevent incorporating additional circuitry in the electronic device. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     Embodiments presented herein provide a “true” full-duplex transceiver that enables transmitting and receiving wireless signals at the same time and over the same frequency range. Accordingly, the full-duplex transceiver enables an increased bandwidth available for receiving and transmitting signals. For example, the available bandwidth for both receiving and transmitting may be about 100 MHZ to about 200 MHz. In some embodiments, the bandwidth for both receiving and transmitting may be about 500 MHz to about 1000 MHz. Further, the full-duplex transceiver enables a single cable to be used between integrated circuits of an electronic device for transmitting and receiving signals at the same frequency simultaneously, thus reducing the size of the electronic device or enabling more circuitry to be added to the electronic device. 
     The embodiments presented herein also maintain or improve isolation of the transmitter and receiver of an electronic device. In particular, the embodiments disclosed herein include two circuit paths between one or more antennas and an isolation circuit. The isolation circuit is disposed between, and coupled to a transmitter circuit and a receiver circuit. The isolation circuit can further isolate the transmitter circuit from received signals and isolate the receiver circuit from transmission signals. A non-reciprocal phase shifter may be used to shift a phase of a signal propagating along one of the circuit paths and further improve isolation of the transmitter circuit from received signals and the receiver circuit from transmission signals. 
     In some embodiments, the isolation circuit may include a balun (e.g., a transformer balun) that enables transmission signals to pass through to the transmitter circuit (e.g., via a transformer effect) and blocks the transmission signals from passing through to the receiver circuit, while enabling received signals to pass through to the receiver circuit (e.g., via circuit paths) and blocking the received signals from passing through to the transmitter circuit. In particular, the balun may receive an input signal (e.g., traveling in a first direction) and output two output signals of opposite polarities (e.g., being 180 degrees out of phase from one another), each having half the power of the input signal. For example, the balun may receive a transmission signal from the transmitter circuitry and output a first split transmission signal and a second split transmission signal, where the first and second split transmission signals are out of phase with one another by 180 degrees and each have half the power of the original transmission signal. 
     A phase shifter may be used on at least one of two circuit paths to phase shift at least one of the split transmission signals so that the two split transmission signals are in-phase (e.g., have a zero degree difference in phase). The phase shifter may include a non-reciprocal phase shifter which shifts a phase of a signal therethrough and improves isolation between the transmitter circuit and the receiver circuit. For example, the non-reciprocal phase shifter may shift a phase of a signal by one phase amount (e.g., +90 degrees) when the signal propagates through the non-reciprocal phase shifter in a first direction, but shifts a phase of a signal by another phase amount (e.g., −90 degrees) when the signal propagates through the non-reciprocal phase shifter in a second direction opposite of the first direction. 
     In some embodiments, the non-reciprocal phase shifter may be disposed on one of the two circuit paths and shift a phase of a portion of the split signal propagating therethrough. In that case, an additional phase shifter may be used to shift a phase of an additional portion of the split signal on the other circuit path opposite the non-reciprocal phase shifter. The additional phase shifter may be a bidirectional phase shifter and shift a phase of the signal therethrough by the same phase amount regardless of a direction of the signal. For example, the additional phase shifter may shift a phase of a signal therethrough by a third amount (e.g., +90 degrees) when the signal propagates through the additional phase shifter in the first direction and/or in the second direction. 
     As discussed above, the isolation circuit (e.g., balun) may split a transmission signal and combine a received signal. The split transmission signal from the transmitter circuit on the two circuit paths may be balanced. In that case, there is no voltage at the input of the receiver circuit, and, accordingly, no voltage from the transmission signal leaks into the receiver circuit. 
     The balun (e.g., isolation circuit) may also receive two input signals (e.g., traveling in the second direction) and output a combined output signal to the receive circuit. For example, the one or more antennas of the electronic device may receive a received signal from the one or more antennas and split the signal into two halves along the two circuit paths. The balun may receive the two split received signals and combine them to output a combined received signal having twice the bandwidth of the FDD transceiver. 
     When the received signal is received by the one or more antennas and split along the two circuit paths, the split received signals are in-phase. A phase of each of the split received signals may be shifted by the same amount by the non-reciprocal phase shifter on the first path and the bi-directional phase shifter on the second path. Thus, because a phase of each of the split received signals is shifted the same amount, the split received signals arrive at the isolation circuit in-phase. Thus, there is no differential signal at the isolation circuit and thus the received signals do not leak into the transmitter circuit. In this manner, the isolation circuit enables transmission signals to pass through to the transmitter circuit and block the transmission signals from passing through to the receiver circuit, while enabling received signals to pass through to the receiver circuit (e.g., via the circuit paths) and blocking the received signals from passing through to the transmitter circuit. Accordingly, the isolation circuit provides isolation between the transmitter circuit and the receiver circuit. 
     For a frequency division duplex (FDD) transceiver, the bandwidth of the received signal and the transmission signal may have been limited. That is, the available bandwidth for each of the transmission signal and the received signal for an FDD transceiver may have been limited to about 20 MHz. Instead, the disclosed embodiments may utilize a full-duplex transceiver that enables transmission and receipt of signals at the same frequency simultaneously having at least double the available bandwidth of the FDD transceiver. 
     Further, the balun and non-reciprocal phase shifter may enable a single cable to be used between integrated circuits for transmitting and receiving signals. That is, because the transmission and received signals are within the same frequency range, a first separate cable for the transmission signal corresponding to a first frequency range and a second separate cable for the receive signal corresponding to a second frequency range may be avoided. 
     In one embodiment, an electronic device for full duplex communications is provided. The electronic device includes one or more antennas coupled to a first signal path and a second signal path. The electronic device also includes a first balun coupling the first signal path to the second signal path. The electronic device also includes transmitter circuitry coupled to the first balun. The electronic device also includes receiver circuitry coupled to the first balun opposite the transmitter circuitry. The electronic device also includes a bidirectional phase shifter disposed on the first signal path. The electronic device also includes a non-reciprocal phase shifter disposed on the second signal path. 
     In another embodiment, an electronic device is provided which includes one or more antennas. The electronic device also includes a transmit circuit configured to transmit a transmission signal via the one or more antennas. The electronic device also includes a receive circuit configured to receive a receive signal via the one or more antennas. The electronic device also includes an isolation circuit coupled to the one or more antennas, the transmit circuit, and the receive circuit, the isolation circuit configured to isolate the transmit circuit from the receive signal and to isolate the receive circuit from the transmission signal, the isolation circuit configured to couple to the one or more antennas via a first signal path, and the isolation circuit configured to couple to the one or more antennas via a second signal path. The electronic device also includes a non-reciprocal phase shifter disposed on the first signal path and configured to shift a phase of at least a portion of the transmission signal therethrough by a first phase amount and configured to shift a phase of at least a portion of the receive signal therethrough by a second phase amount. 
     In yet another embodiment, an electronic device is provides which includes antenna means and means for transmitting a transmission signal via the antenna means. The electronic device also includes means for receiving a receive signal via the antenna means. The electronic device also includes means for isolating the transmitting means from the receive signal and for isolating the receiving means from the transmission signal, the isolating means coupled to a first signal path and a second signal path. The electronic device also includes means for shifting a phase of a first portion of the transmission signal on the first signal path to generate a shifted first portion of the transmission signal on the first signal path. The electronic device also includes means for shifting a phase of a second portion of the transmission signal on the second signal path to generate a shifted second portion of the transmission signal on the second signal path. The electronic device also includes means for constructively combining the shifted first portion of the transmission signal on the first signal path and the shifted second portion of the transmission signal on the second signal path into a combined signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings described below. 
         FIG.  1    is a block diagram of an electronic device, according to an embodiment of the present disclosure. 
         FIG.  2    is a perspective view of a notebook computer representing an embodiment of the electronic device of  FIG.  1   . 
         FIG.  3    is a front view of a handheld device representing another embodiment of the electronic device of  FIG.  1   . 
         FIG.  4    is a front view of another handheld device representing another embodiment of the electronic device of  FIG.  1   . 
         FIG.  5    is a front view of a desktop computer representing another embodiment of the electronic device of  FIG.  1   . 
         FIG.  6    is a perspective view of a wearable electronic device representing another embodiment of the electronic device of  FIG.  1   . 
         FIG.  7    is an example block diagram of a communication system of the electronic device of  FIG.  1   , according to an embodiment of the present disclosure. 
         FIG.  8    is a schematic diagram of an example transceiver circuitry of the electronic device of  FIG.  1   , according to an embodiment of the present disclosure. 
         FIG.  9 A  is a schematic diagram of a receive circuit of the example transceiver circuitry of  FIG.  7   , according to an embodiment of the present disclosure. 
         FIG.  9 B  is a schematic diagram of a transmission circuit of the example transceiver circuitry of  FIG.  7   , according to an embodiment of the present disclosure. 
         FIG.  10 A  is a schematic diagram of example transceiver circuitry of the electronic device of  FIG.  1    illustrating a path of a transmission (TX) signal, according to an embodiment of the present disclosure. 
         FIG.  10 B  is a schematic diagram of example transceiver circuitry of the electronic device of  FIG.  1    illustrating a path of a received (RX) signal, according to an embodiment of the present disclosure. 
         FIG.  10 C  is a schematic diagram of example transceiver circuitry of the electronic device of  FIG.  1   , according to an embodiment of the present disclosure. 
         FIG.  11    is a schematic diagram of an example non-reciprocal phase shifter of the transceiver circuitry of  FIG.  8   , according to an embodiment of the present disclosure. 
         FIG.  12    is a schematic diagram of an example bi-directional phase shifter of the transceiver circuitry of  FIG.  8   , according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Use of the term “approximately,” “near,” “about”, and/or “substantially” should be understood to mean including close to a target (e.g., design, value, amount), such as within a margin of any suitable or contemplatable error (e.g., within 0.1% of a target, within 1% of a target, within 5% of a target, within 10% of a target, within 25% of a target, and so on). Also, full-duplexing, as referred to herein, refers to transmitting and receiving wireless signals at the same time and over the same frequency range, as opposed to frequency division duplexing (FDD), where signals are transmitted over a first frequency range and received over a second frequency range different from the first frequency range. 
     With the foregoing in mind, there are many suitable communication devices that may include and use the transceiver circuitry described herein. Turning first to  FIG.  1   , an electronic device  10  according to an embodiment of the present disclosure may include, among other things, a processor core complex  12  including one or more processor(s), memory  14 , nonvolatile storage  16 , a display  18 , input structures  22 , an input/output (I/O) interface  24 , a network interface  26 , and a power source  29 . The various functional blocks shown in  FIG.  1    may include hardware elements (including circuitry), software elements (including computer code stored on a computer-readable medium) or a combination of both hardware and software elements. It should be noted that  FIG.  1    is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in electronic device  10 . 
     By way of example, the electronic device  10  may represent a block diagram of the notebook computer depicted in  FIG.  2   , the handheld device depicted in  FIG.  3   , the handheld device depicted in  FIG.  4   , the desktop computer depicted in  FIG.  5   , the wearable electronic device depicted in  FIG.  6   , or similar devices. It should be noted that the processor(s)  12  and other related items in  FIG.  1    may be generally referred to herein as “data processing circuitry.” Such data processing circuitry may be embodied wholly or in part as software, software, hardware, or any combination thereof. Furthermore, the processor(s)  12  and other related items in  FIG.  1    may be a single contained processing module or may be incorporated wholly or partially within any of the other elements within the electronic device  10 . 
     In the electronic device  10  of  FIG.  1   , the processor(s)  12  may be operably coupled with a memory  14  and a nonvolatile storage  16  to perform various algorithms Such programs or instructions executed by the processor(s)  12  may be stored in any suitable article of manufacture that includes one or more tangible, computer-readable media. The tangible, computer-readable media may include the memory  14  and/or the nonvolatile storage  16 , individually or collectively, to store the instructions or routines. The memory  14  and the nonvolatile storage  16  may include any suitable articles of manufacture for storing data and executable instructions, such as random-access memory, read-only memory, rewritable flash memory, hard drives, and optical discs. In addition, programs (e.g., an operating system) encoded on such a computer program product may also include instructions that may be executed by the processor(s)  12  to enable the electronic device  10  to provide various functionalities. 
     In certain embodiments, the display  18  may be a liquid crystal display (LCD), which may facilitate users to view images generated on the electronic device  10 . In some embodiments, the display  18  may include a touch screen, which may facilitate user interaction with a user interface of the electronic device  10 . Furthermore, it should be appreciated that, in some embodiments, the display  18  may include one or more light-emitting diode (LED) displays, organic light-emitting diode (OLED) displays, active-matrix organic light-emitting diode (AMOLED) displays, or some combination of these and/or other display technologies. 
     The input structures  22  of the electronic device  10  may enable a user to interact with the electronic device  10  (e.g., pressing a button to increase or decrease a volume level). The I/O interface  24  may enable electronic device  10  to interface with various other electronic devices, as may the network interface  26 . The network interface  26  may include, for example, one or more interfaces for a personal area network (PAN), such as a BLUETOOTH® network, for a local area network (LAN) or wireless local area network (WLAN), such as an 802.11x WI-FI® network, and/or for a wide area network (WAN), such as a 3rd generation (3G) cellular network, universal mobile telecommunication system (UMTS), 4th generation (4G) cellular network, long term evolution (LTE®) cellular network, long term evolution license assisted access (LTE-LAA) cellular network, 5th generation (5G) cellular network, and/or New Radio (NR) cellular network. In particular, the network interface  26  may include, for example, one or more interfaces for using a Release-15 cellular communication standard of the 5G specifications that include the millimeter wave (mmWave) frequency range (e.g., 24.25-300 gigahertz (GHz)). The network interface  26  of the electronic device  10  may allow communication over the aforementioned networks (e.g., 5G, Wi-Fi, LTE-LAA, and so forth). 
     The network interface  26  may also include one or more interfaces for, for example, broadband fixed wireless access networks (e.g., WIMAX®), mobile broadband Wireless networks (mobile WINMAX®), asynchronous digital subscriber lines (e.g., ADSL, VDSL), digital video broadcasting-terrestrial (DVB-T®) network and its extension DVB Handheld (DVB-H®) network, ultra-wideband (UWB) network, alternating current (AC) power lines, and so forth. 
     As illustrated, the network interface  26  may include a transceiver  30 . In some embodiments, all or portions of the transceiver  30  may be disposed within the processor core complex  12 . The transceiver  30  may support transmission and receipt of various wireless signals via one or more antennas (not shown in  FIG.  1   ). In particular, the transceiver  30  may support simultaneous transmission and receipt of wireless signals at the same frequency or frequency range (e.g., full-duplex operation). As discussed in more detail below, the transceiver  30  may have a single I/O port for transmission and receipt of wireless signals. In some cases, changing impedance of the one or more antennas may disturb the duplex function and/or degrade isolation between the transmit path and the receive path. To prevent such disruption, an antenna tracker may be used to substantially match an impedance of the one or more antennas. 
     In particular, the transceiver  30  may include a duplexer (not shown in  FIG.  1   ), such as an electrical balanced duplexer. The duplexer may enable bidirectional communication over a single path while separating signals traveling in each direction from one another. For example, the duplexer may isolate a transmitter of the electronic device  10  from a received signal and/or isolate a receiver of the electronic device  10  from a transmission signal (e.g., isolate the transmitter from the receiver, and vice versa). In some embodiments, the duplexer may include a balance-unbalance transformer (e.g., a balun) that performs or facilitates performing the isolation. 
     In some embodiments, the electronic device  10  communicates over various wireless networks (e.g., WI-FI®, WIMAX®, mobile WIMAX®, 4G, LTE®, 5G, and so forth) using the transceiver  30 . The transceiver  30  may transmit and receive RF signals to support voice and/or data communication in wireless applications such as, for example, PAN networks (e.g., BLUETOOTH®), WLAN networks (e.g., 802.11x WI-FI®), WAN networks (e.g., 3G, 4G, 5G, NR, and LTE® and LTE-LAA cellular networks), WIMAX® networks, mobile WIMAX® networks, ADSL and VDSL networks, DVB-T® and DVB-H® networks, UWB networks, and so forth. The power source  29  of the electronic device  10  may include any suitable source of power, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. 
     In certain embodiments, the electronic device  10  may take the form of a computer, a portable electronic device, a wearable electronic device, or other type of electronic device. Such computers may be generally portable (such as laptop, notebook, and tablet computers), or generally used in one place (such as conventional desktop computers, workstations, and/or servers). In certain embodiments, the electronic device  10  in the form of a computer may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. of Cupertino, Calif. By way of example, the electronic device  10 , taking the form of a notebook computer  10 A, is illustrated in  FIG.  2    in accordance with one embodiment of the present disclosure. The depicted notebook computer  10 A may include a housing or enclosure  36 , a display  18 , input structures  22 , and ports of an I/O interface  24 . In one embodiment, the input structures  22  (such as a keyboard and/or touchpad) may be used to interact with the computer  10 A, such as to start, control, or operate a graphical user interface (GUI) and/or applications running on computer  10 A. For example, a keyboard and/or touchpad may allow a user to navigate a user interface and/or application interface displayed on display  18 . 
       FIG.  3    depicts a front view of a handheld device  10 B, which represents one embodiment of the electronic device  10 . The handheld device  10 B may represent, for example, a portable phone, a media player, a personal data organizer, a handheld game platform, or any combination of such devices. By way of example, the handheld device  10 B may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif. The handheld device  10 B may include an enclosure  36  to protect interior components from physical damage and/or to shield them from electromagnetic interference. The enclosure  36  may surround the display  18 . The I/O interfaces  24  may open through the enclosure  36  and may include, for example, an I/O port for a hardwired connection for charging and/or content manipulation using a standard connector and protocol, such as the Lightning connector provided by Apple Inc. of Cupertino, Calif., a universal serial bus (USB), or other similar connector and protocol. 
     The input structures  22 , in combination with the display  18 , may allow a user to control the handheld device  10 B. For example, the input structures  22  may activate or deactivate the handheld device  10 B, navigate the user interface to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device  10 B. Other input structures  22  may provide volume control, or may toggle between vibrate and ring modes. The input structures  22  may also include a microphone that may obtain a user&#39;s voice for various voice-related features, and a speaker that may enable audio playback and/or certain phone capabilities. The input structures  22  may also include a headphone input that may provide a connection to external speakers and/or headphones. 
       FIG.  4    depicts a front view of another handheld device  10 C, which represents another embodiment of the electronic device  10 . The handheld device  10 C may represent, for example, a tablet computer, or one of various portable computing devices. By way of example, the handheld device  10 C may be a tablet-sized embodiment of the electronic device  10 , which may be, for example, a model of an iPad® available from Apple Inc. of Cupertino, Calif. 
     Turning to  FIG.  5   , a computer  10 D may represent another embodiment of the electronic device  10  of  FIG.  1   . The computer  10 D may be any computer, such as a desktop computer, a server, or a notebook computer, but may also be a standalone media player or video gaming machine. By way of example, the computer  10 D may be an iMac®, a MacBook®, or another similar device by Apple Inc. of Cupertino, Calif. It should be noted that the computer  10 D may also represent a personal computer (PC) by another manufacturer. A similar enclosure  36  may be provided to protect and enclose internal components of the computer  10 D, such as the display  18 . In certain embodiments, a user of the computer  10 D may interact with the computer  10 D using various peripheral input structures  22 , such as the keyboard  22 A or mouse  22 B (e.g., input structures  22 ), which may connect to the computer  10 D. 
     Similarly,  FIG.  6    depicts a wearable electronic device  10 E representing another embodiment of the electronic device  10  of  FIG.  1    that may operate using the techniques described herein. By way of example, the wearable electronic device  10 E, which may include a wristband  43 , may be an Apple Watch® by Apple Inc. of Cupertino, Calif. However, in other embodiments, the wearable electronic device  10 E may include any wearable electronic device such as, for example, a wearable exercise monitoring device (e.g., pedometer, accelerometer, heart rate monitor), or other device by another manufacturer. The display  18  of the wearable electronic device  10 E may include a touch screen display  18  (e.g., LCD, LED display, OLED display, active-matrix organic light emitting diode (AMOLED) display, and so forth), as well as input structures  22 , which may allow users to interact with a user interface of the wearable electronic device  10 E. 
     As mentioned above, the transceiver  30  of the electronic device  10  may include a transmitter and a receiver that are coupled to an antenna to enable the electronic device  10  to transmit and receive wireless signals. Certain electronic devices may include isolation circuitry having an electrical balanced duplexer (EBD) that isolates the transmitter from received signals, and the receiver from transmission signals, thus reducing interference when communicating. In such electronic devices, an impedance tuner may be used to match the impedance of the antenna to increase effectiveness of this isolation. However, the available bandwidth for transmitting and receiving signals may be limited by a half-duplex transceiver. As a result, transmission of signals between integrated circuits of the electronic device  10  and wireless communications with external devices may be slow. Further, separate cables may be needed to transmit and receive signals at the same frequency using a half-duplex transceiver. The additional cable consumes additional space or real estate on the integrated circuit and thus limits a minimum size of the integrated circuit. 
     Thus, the transceiver  30  of the electronic device  10  may be a full-duplex transceiver to double the available bandwidth for transmitting and receiving signals at the same frequency simultaneously. 
     transmission path for transmission signals sent from the transmitter may branch between the antenna and the impedance tuner. As a result, some of the power used to transmit a transmission signal through the antenna may be lost when the transmission signal branches to the impedance tuner. Similarly, the reception path for received signals received from the antenna may branch between the receiver and the impedance tuner. As a result, some of the power in the received signal received at the receiver may be lost (e.g., insertion loss) when the received signal branches to the impedance tuner. 
     Embodiments herein provide various apparatuses and techniques to improve available bandwidth for the transmission and received signals while maintaining and/or improving isolation of the transmitter and receiver of the electronic device  10 . To do so, the embodiments disclosed herein include a full duplex transceiver (e.g., one that enables transmitting and receiving wireless signals at the same time and over the same frequency range) with two circuit paths between one or more antennas and an isolation circuit. A non-reciprocal phase shifter may be disposed on one of the two circuit paths to shift a phase of a signal therethrough such that the signal through the phase shifter can be constructively combined with a signal on the other circuit path. For example, the non-reciprocal phase shifter may shift a phase of a signal by one phase amount (e.g., +90 degrees) when the signal propagates through the non-reciprocal phase shifter in a first direction, and shift a phase of a signal by another phase amount (e.g., −90 degrees) when the signal propagates through the non-reciprocal phase shifter in a second direction, opposite of the first direction. While phases of the signals may be discussed herein with respect to degrees, it should be understood that alternative angular units of measure may be used, such as radians. For example, 90 degrees of phase shift may be equivalent to about 1.5708 radians of phase shift. 
     In some embodiments, the non-reciprocal phase shifter may be disposed on one of the two circuit paths and shift a phase of a portion of the split signal propagating therethrough. The non-reciprocal phase shifter may improve the isolation of the transmitter and the receiver of the electronic device  10  (e.g., by ensuring that the signal on its circuit path is in-phase with the signal on the other circuit path). 
     With the foregoing in mind,  FIG.  7    is an example block diagram of a communication system  50  of the electronic device of  FIG.  1   , according to an embodiment of the present disclosure. The communication system  50  includes a first integrated circuit (IC)  52  coupled to a second IC  54 . The ICs  52 ,  54  may represent various ICs in electronic device  10  discussed with respect to  FIG.  1   . One or more antennas  79  may be coupled to the second IC  54  to wirelessly transmit and receive signals. As illustrated, the first IC  52  is an intermediate frequency (IF) transceiver silicon IC and the second IC  54  is a radio frequency (RF) transceiver silicon IC. In some embodiments, the first IC  52  may be used to transmit electronic signals (e.g., data) between various ICs in the electronic device  10 . Additionally or alternatively, the first IC  52  may include a baseband silicon IC which may manage functions of the second IC  54  (and other ICs of the electronic device  10 ), such as transmission and receipt of wireless signals via the one or more antennas  79 . In some embodiments, the second IC  54  may transmit and receive various wireless signals via the one or more antennas  79 . The signals transmitted and received by the second IC  54  may be in a frequency suitable for wireless communication, for example, in the range of 3 kHz-300 GHz. 
     In the case of a frequency division duplex (FDD) transceiver, where signals are transmitted over a first frequency range and received over a second frequency range, the first IC  52  may be coupled to the second IC  54  via a first path  56  and a second path  58 . The first path  56  may be used to transmit signals from the first IC  52  to the second IC  54  to be transmitted via one or more antennas  79 . The second path  58  may be used to transmit signals received by the one or more antennas  79  from the second IC  54  to the first IC  52 . That is, the paths  56 ,  58  may be unidirectional. However, the two paths  56 ,  58  between the ICs  52 ,  54  may takes up valuable space in the electronic device  10  or prevent incorporating additional circuitry in the electronic device  10 . 
     Embodiments described herein enable removal of one of the paths  56 ,  58  between the ICs  52 ,  54 . That is, a single path  56  may be used to send signals between the first IC  52  and the second IC  54 , regardless of a direction of the signal, as transmission and received signals may share the same frequency range. That is, the signals on the single path may include transmission signals to be transmitted via the one or more antennas  79  and signals received via the one or more antennas  79 . By reducing a number of paths between the ICs  52 ,  54 , a size of a footprint of the circuitry of the in the electronic device  10  may also be reduced, and/or additional circuitry may be incorporated in the electronic device  10 . 
       FIG.  8    is a schematic diagram of example transceiver circuitry  70  of the electronic device  10 , according to an embodiment of the present disclosure. In some embodiments, the example transceiver circuitry  70  may be disposed in the transceiver  30  discussed with respect to  FIG.  1   . In other embodiments, the transceiver circuitry  70  may be disposed in the network interface  26  and coupled to the transceiver  30 . With respect to  FIG.  7   , the transceiver circuitry  70  may be disposed in one or both of the ICs  52 ,  54 . 
     As illustrated, the transceiver circuitry  70  includes isolation circuit  76  disposed between a transmit (TX) circuit  72  and a receive (RX) circuit  74 . The isolation circuit  76  is coupled to the TX circuit  72  and is coupled to the RX circuit  74 . The isolation circuit  76  may enable transmission signals to pass through to the TX circuit  72  (e.g., via a transformer effect) and block the transmission signals from passing through to the RX circuit  74 , while enabling received signals to pass through to the RX circuit  74  (e.g., via circuit paths) and blocking the received signals from passing through to the TX circuit  72 . 
     The first path  92  and the second path  94  each couple the isolation circuit  76  to one or more antennas  79  via a node  77 . The first path  92  may be parallel to and opposite the second path  94 . The first path  92  and the second path  94  may be bidirectional paths along which a signal to be transmitted (e.g., a TX signal) splits and travels from the TX circuit  72  to the one or more antennas  79 . Similarly, a signal received via the one or more antennas  79  (e.g., an RX signal) may split and travel along the first path  92  and the second path  94  to the RX circuit  74 . 
     In some embodiments, the TX signal from the TX circuit  72  may be divided by the isolation circuit  76 . In that case, a first portion of the TX signal may propagate along the first path  92  and a second portion of the TX signal may propagate along the second path  94 . The first portion of the signal and the second portion of the signal may be combined at the node  77 . Similarly, a signal received via the one or more antennas  79  may be split into a first portion of the RX signal and a second portion of the RX signal. The first portion of the RX signal may propagate along the first path  92  and the second portion of the RX signal may propagate along the second path  94 . The first and second portions of the RX signal may be combined at the isolation circuit  76  and provided to the RX circuit  74 . It should be noted that splitting the TX signal at the isolation circuit from the TX circuit  72  or the RX signal at the node  77  from the one or more antennas  79 , without combining the split signals back together, may cause an insertion loss equal to about half of a power of the TX signal output from the TX circuit  72  or about half of a power of the RX signal output from the one or more antennas  79 , respectively. In some embodiments, the insertion loss may be about 3 decibels (dB). 
     The isolation circuit  76  may include a balun (e.g., a transformer balun) that enables TX signals to pass through to the TX circuit  72  (e.g., via a transformer effect) and blocks the TX signals from passing through to the RX circuit  74 , while enabling RX signals to pass through to the RX circuit  74  (e.g., via circuit paths) and blocking the RX signals from passing through to the TX circuit  72 . In particular, the balun of the isolation circuit  76  may receive a TX signal from the TX circuit  72 , and output a first split TX signal on the first path  92  and a second split TX signal on the second path  94 , where the first and second split TX signals are out of phase with one another (e.g., by approximately 180 degrees). Each of the split TX signals may have half the power of the original TX signal. The split TX signal from the TX circuit  72  on the first path  92  and the second path  94  may be balanced. Thus, there is no voltage at the input of the RX circuit  74 , and, accordingly, no voltage from the TX signal leaks into the RX circuit  74 . Similarly, when an RX signal is received by the one or more antennas  79  and split at the node  77 , the split RX signals are in-phase. Thus, there is no differential signal at the isolation circuit  76  and thus the RX signals do not leak into the TX circuit  72 . In this manner, the isolation circuit  76  enables TX signals to pass through to the TX circuit  72  and block the TX signals from passing through to the RX circuit  74 , while enabling received signals to pass through to the RX circuit  74  (e.g., via circuit paths) and blocking the received signals from passing through to the TX circuit  72 . 
     Because the split TX signals are out of phase, the disclosed embodiments include phase shifting circuit  78  that may be disposed along the first path  92  and/or the second path  94 . Moreover, the phase shifting circuit  78  is coupled to the isolation circuit  76  via the first path  92  and/or the second signal path  94 . The phase shifting circuit  78  is coupled to the one or more antennas  79  via the first path  92  and/or the second path  94 , and the node  77 . Specifically, the phase shifting circuit  78  may include one or more phase shifters disposed along the first path  92  and/or the second path  94 . 
     The phase shifting circuit  78  may shift a phase of a signal along a respective path  92 ,  94  to substantially correlate or match a phase of a signal along the other path  92 ,  94 , in either direction (e.g., for both TX and RX signals). For example, because the phase of the first portion of the TX signal on the first path  92  may be about 180 degrees out of phase compared to the second portion of the TX signal on the second path  94 , in some embodiments, the phase shifting circuit  78  may shift a phase of the first portion of the TX signal on the first path  92  by about 180 degrees. After the phase of the first portion of the TX signal is shifted by the phase shifting circuit  78 , the phase-shifted first portion and the second portion of the TX signal are substantially in-phase with each other. Thus, the phase shifting circuit  78  may shift a phase of a signal along the first path  92 , but not the second path  94 . 
     In other embodiments, the phase shifting circuit  78  may shift a phase of a signal along both the first path  92  and the second path  94 . For example, the phase shift of the first signal on the first path  92  may be opposite the phase shift of the second signal on the second path  94 . That is, the phase shifting circuit  78  may shift the phase of the first signal on the first path  92  by +90 degrees, and shift the phase of the second signal on the second path  94  by −90 degrees. As another example, if the phase shifting circuit  78  may shift the phase of the first signal on the first path  92  by +100 degrees, and shift the phase of the second signal on the second path  94  by −80 degrees. In any case, the phase shifting circuit  78  may shift the phase of the first and second signals to enable the split signals to be constructively combined. 
     Without the phase shifting circuit  78 , the first signal on the first path  92  and the second signal on the second path  94  may be out-of-phase. If the first signal on the first path  92  and the second signal on the second path  94  were combined without placing the signals in-phase, an amplitude of the combined signal may be reduced compared to the original signal from the TX circuit  72  or the one or more antennas  79 . As such, an insertion loss caused by the isolation circuit  76  might be amplified without placing the signals in-phase. 
     Shifting a phase of the first portion of the TX signal on the first path  92  enables that signal to be combined with a second portion of the TX signal on the second path  94 . Thus, the two signals along the respective paths  92 ,  94  can be constructively combined at the node  77  prior to propagate to the one or more antennas  79  to recover power lost in the TX signal due to splitting from the isolation circuit  76 . 
     As illustrated, the node  77  is in the form of a “T-line” junction (e.g., three circuit paths joined together at the node  77 ). In additional or alternative embodiments, the node  77  may include a combiner circuit or device, such as a balun, a Wilkinson power divider, a capacitor, or the like. As such, the phase shifting circuit  78  may be deactivated for RX signals, and thus be a unidirectional phase shifter. In other embodiments, the node  77  may cause a phase difference (e.g., approximately a 180 degree phase difference) between the first portion of the RX signal traveling along the first path  92  and the second portion of the RX signal traveling along the second path  94 , and, as such, the phase shifting circuit  78  may be bidirectional and shift a phase of the first portion of the RX signal traveling along the first path  92  and/or the second portion of the RX signal traveling along the second path  94  to ensure that the portions of the RX signal are in-phase. In such cases, the node  77  may include, for example, a balun, which may cause the phase difference between the two portions of the RX signal. 
     The node  77  may combine the shifted signals from the phase shifting circuit  78  and provide the combined signal to the one or more antennas  79  to be transmitted therefrom. The node  77  may be any RF combiner circuit, such as a balun, a Wilkinson power divider, a capacitor, a T-line junction, and the like. Depending on the type of combiner circuit used at the node  77 , the combiner circuit may shift a phase of a portion of a signal received by the one or more antennas  79 . For example, a signal received at the one or more antennas  79  may be split into a first portion propagated along the first path  92  and a second portion propagated along the second path  94 . However, the combiner circuit at the node  77  may shift a phase of at least one of the first portion and the second portion. Such is the case if the combiner circuit is implemented as a balun (e.g., a transformer balun). In that case, the phase shifting circuit  78  may shift a phase of at least one of the first portion and the second portion of the received signal, such that the first portion of the signal is in-phase with the second portion of the signal at the isolation circuit  76 . To enable the first portion of the signal to be in-phase with the second portion of the signal at the isolation circuit  76 , the phase shifting circuit  78  may provide bidirectional phase shifting to shift an RX signal propagating from the one or more antennas  79  to the isolation circuit  76 , as well as a TX signal propagating from the isolation circuit  76  to the one or more antennas  79 . The first portion and the second portion are then combined at the isolation circuit  76  and provided to the RX circuit  74 . 
     Similarly, the first portion of an RX signal on the first path  92  may be combined with the second portion of the RX signal on the second path  94  at the isolation circuit  76 . The RX signal received at the one or more antennas  79  may be in single-ended mode. Thus, the first portion of the RX signal on the first path  92  is in-phase with the second portion of the RX signal on the second path  94 . 
       FIG.  9 A  is a schematic diagram of a receive circuit (e.g., the RX circuit)  74  of the example transceiver circuitry of  FIG.  7   , according to an embodiment of the present disclosure. As illustrated, the RX circuit  74  may include, for example, a low noise amplifier (LNA)  80 , filter circuitry  81 , a demodulator  82 , and an analog-to-digital converter (ADC)  83 . One or more signals received by the one or more antennas  79  may be sent to the RX circuit  74  via the isolation circuit  76 . In some embodiments, the RX circuit  74  may include components in addition to or alternative to the LNA  80 , filter circuitry  81 , the demodulator  82 , and the ADC,  83 , such as a mixer, a digital down converter, and the like. 
     The LNA  80  and filter circuitry  81  may receive the combined RX signal (e.g., the first and the second portions of the RX signal) received by the one or more antennas  79  and combined by the isolation circuit  76 . The LNA  80  may amplify the combined RX signal to a suitable level for the rest of the circuitry to process. 
     The filter circuitry  81  may include one or more types of filters such as bandpass filter, a low pass filter, or a decimation filter, or any combination thereof. The filter circuitry  81  may remove undesired noise from the RX signal, such as cross-channel interference. The filter circuitry  81  may also remove additional signals received by the one or more antennas  79  which are at frequencies other than the desired signal. 
     The filtered RX signal is sent to the demodulator  82 . The demodulator  82  may remove the RF envelope and extract a demodulated signal from the filtered RX signal for processing. The ADC  83  receives the demodulated analog signal and converts the signal to a digital signal so that it can be further processed by the electronic device  10 . 
       FIG.  9 B  is a schematic diagram of a transmission circuit (e.g., the TX circuit)  72 , according to an embodiment of the present disclosure. As illustrated, the TX circuit  72  may include, for example, filter circuitry  85 , a power amplifier (PA)  86 , a modulator  87 , and a digital-to-analog converter (DAC)  88 . In some embodiments, the TX circuit  72  may include components in addition to or alternative to the filter circuitry  85 , the PA  86 , the modulator  87 , and the DAC  88  such as a digital up converter, etc. 
     A digital signal containing information to be transmitted via the one or more antennas  79  is provided to the DAC  88 . The DAC  88  converts the digital signal to an analog signal. The modulator  87  may combine the converted analog signal with a carrier signal to generate a radio wave. 
     The PA  86  receives signal the modulated signal from the modulator  87 . The PA  86  amplifies the modulated signal to a suitable level to drive transmission of the signal via the one or more antennas  79 . Similar to the filter circuitry  81 , the filter circuitry  85  of the TX circuit  72  may remove undesirable noise from the amplified signal to be transmitted via the one or more antennas  79 . In some embodiments, a PA, such as the PA  86 , may be disposed within the transmitter in addition to or alternative to the PA  86  in the TX circuit  72 . 
       FIG.  10 A  is a schematic diagram of example transceiver circuitry  100  of the electronic device of  FIG.  1    illustrating a path of a transmission (TX) signal, according to an embodiment of the present disclosure. The example transceiver circuitry  100  is substantially similar to the schematic diagram of the transceiver circuitry  70  in  FIG.  8   , with the phase shifting circuitry  78  including a first phase shifter  102  on the first path  92  and a second phase shifter  104  on the second path  94 . A TX signal  112  is depicted as propagating through the transceiver circuitry  70  along example paths  106 ,  108 . The isolation circuit  76  is represented by a balun  110 . Although not shown, an impedance matching circuit (e.g., an antenna tracker) discussed with respect to  FIG.  10 C  may be included in the transceiver circuitry  100  to improve isolation between the RX circuit  74  and the TX circuit  72 . 
     As discussed above, the TX signal  112  is provided to the balun  110  by the TX circuit  72  to be transmitted via the one or more antennas  79 . In addition to preventing an RX signal from entering the TX circuit  72 , the balun  110  also splits the TX signal  112  into a first portion (+TX)  106  and a second portion (−TX)  108 . The first portion (+TX)  106  propagates along the first path  92  and the second portion (−TX)  108  propagates along the second path  94 . 
     As discussed above, a phase of the first portion (+TX)  106  may be out of phase from the second portion (−TX)  108  due to the balun  110 . Thus, the phase shifters  102 ,  104  shift a phase of the respective portions of the TX signal  112  such that the first portion (+TX)  106  and the second portion (−TX)  108  are substantially in-phase at the node  77 . As discussed above, in some embodiments, one or both phases of the first and second portions  106 ,  108  may be shifted as long as the phases of the respective portions are substantially in-phase at the node  77 . Shifting a phase of the one or both of the portions  106 ,  108  enables the portions  106 ,  108  to be constructively combined at the node  77 , thereby reducing or substantially eliminating the insertion loss caused by the isolation circuit. 
     In some embodiments, the phase shifter  102  on the first path  92  may be a non-reciprocal phase shifter, as discussed with respect to  FIG.  11    below. As such, the phase shifter  102  may be a bidirectional phase shifter and shift a phase of a signal from the isolation circuit  76  (e.g., the balun  110 ) to the antenna  79  by a first phase amount and shift a phase of a signal from the antenna  79  to the isolation circuit  76  by a second phase amount. In some embodiments, the phase shift by the phase shifter  102  of a portion of the TX signal from the TX circuit  72  to the antenna  79  may be opposite a phase shift by the phase shifter  102  of a portion of the RX signal from the antenna  79  to the RX circuit  74 . For example, as illustrated, the phase shifter  102  may shift a phase of the TX signal therethrough by −90 degrees while the phase shifter  102  may shift a phase of the RX signal therethrough by +90 degrees. 
     The phase shifter  104  on the second path  94  may also be a bidirectional phase shifter that is reciprocal, and thus shift a phase of the signal therethrough by the same phase amount regardless of a direction of the signal. For example, the phase shifter  104  may shift a phase of a signal from the antenna  79  to the isolation circuit  76  and from the isolation circuit  76  to the antenna  79  by the same amount. In some embodiments, the phase shifter  104  may shift a signal therethrough by +90 degrees. Thus, the amount of phase shift provided by the phase shifter  104  may be a fixed amount based on a phase shift caused by the isolation circuit  76  and/or the combiner circuit at the node  77 . 
     In particular, the balun  110 , in splitting the TX signal  112  between the first path  92  and the second path  94 , shifts a phase of the first portion  106  of the TX signal  112  along the first path  92  by +90 degrees and shifts a phase of the second portion  108  of the TX signal  112  by −90 degrees. The non-reciprocal phase shifter  102  shifts a phase of the first portion  106  of the TX signal  112  by −90 degrees, resulting in the first portion  106  of the TX signal  112  being shifted by 0 degrees. Thus, the non-reciprocal phase shifter  102  counteracts the phase shift of the first portion  106  of the TX signal  112  caused by the balun  110 . Similarly, the phase shifter  104  shifts a phase of the second portion  108  of the TX signal  112  by +90 degrees, resulting in the second portion  108  of the TX signal  112  being shifted by 0 degrees, thus counteracting the phase shift of the second portion  108  caused by the balun  110 . In that case, the shifted first portion  106  of the TX signal  112  on the first path  92  and the shifted second portion  108  of the TX signal  112  on the second path  94  are in-phase (e.g., both being shifted by 0 degrees), and can be constructively combined at the node  77  and transmitted via the one or more antennas  79 . In this manner, the phase shifters  102 ,  104  enable constructive combination of the first portion  106  of the TX signal  112  and the second portion  108  of the TX signal  112 . 
     Advantageously, the non-reciprocal phase shifter  102  may improve the isolation between the TX circuit  72  and the RX circuit  74  by accurately balancing the portions  106 ,  108  of the TX signal  112 , resulting in zero voltage at the input of the RX circuit  74 , thus preventing voltage from the TX signal  112  from leaking to the RX circuit  74 . Further, the non-reciprocal phase shifter  102  in combination with the phase shifter  104  enable the signals on the first path  92  and the second path  94  to be constructively combined at the node  77  and transmitted via the one or more antennas  79 , thereby reducing or substantially eliminating the insertion loss caused by the isolation circuit  76  (e.g., the balun  110 ). 
       FIG.  10 B  is a schematic diagram of an example transceiver circuitry  120  of the electronic device  10  illustrating a path of a received (RX) signal, according to an embodiment of the present disclosure. The transceiver circuitry  120  is substantially similar to the schematic diagram of the transceiver circuitry  100  in  FIG.  10 A . An RX signal  126  is depicted as propagating through the transceiver circuitry  120  along example paths  122 ,  124 . Although not shown, an impedance matching circuit (e.g., an antenna tracker) discussed with respect to  FIG.  10 C  may be included in the transceiver circuitry  120  to improve isolation between the RX circuit  74  and the TX circuit  72 . 
     As discussed above, the RX signal  126  is received via the antenna  79  and propagates through the transceiver circuitry  120  via the example paths  122 ,  124  to the RX circuit  74 . The RX signal  126  is split into a first portion  122  and a second portion  124  at the node  77 . The first portion  122  propagates along the first path  92  and the second portion  124  propagates along the second path  94 . The node  77  may not cause a phase shift of either the first portion  122  or the second portion  124  of the RX signal  126 . However, the phase shifters  102 ,  104  shift a phase of a respective portion  122 ,  124  of the RX signal  126 , such that the shifted first portion  122  and the shifted second portion  124  are in-phase and can be constructively combined by the balun  110 . 
     In particular, the first portion  122  of the RX signal  126  propagates along the first path  92  to the phase shifter  102  and the second portion  124  of the RX signal  126  propagates along the second path  94  to the phase shifter  104 . The phase shifter  104  shifts a phase of the first portion  122  of the RX signal  126  by +90 degrees. Similarly, the phase shifter  102  shifts a phase of the second portion  124  of the RX signal  126  by +90 degrees. Thus, the shifted first portion  122  and the shifted second portion  124  of the RX signal  126  are in-phase (e.g., a phase of the portions  122 ,  124  of the RX signal +90 degrees) and can be constructively combined by the balun  110 . That is, the phase shifters  102 ,  104  enable the first portion  122  and the second portion  124  of the RX signal  126  to be constructively combined. 
       FIG.  10 C  is a schematic diagram of an example transceiver circuitry  130  of the electronic device of  FIG.  1   , according to an embodiment of the present disclosure. The transceiver circuitry  130  is substantially similar to the schematic diagram of the transceiver circuitry  70  in  FIG.  8    with a first balun  110  for the isolation circuitry  76  and a combiner circuit (e.g., a second balun)  132  in place of the node  77 . As depicted, the transceiver circuitry  130  includes the phase shifters  102 ,  104  disposed on the first path  92 . The transceiver circuitry  130  also includes an impedance matching circuit  134  coupled to a second balun  132  at the antenna  79 . 
     As discussed above, the first balun  110  improves isolation between the TX circuit  72  and the RX circuit  74 . Similarly, the second balun  132  may improve isolation between the one or more antennas  79  and the impedance matching circuit  134 . The phase shifters  102 ,  104  are disposed in series on the first path  92  between the first balun  110  and the second balun  132 . Thus, the second phase shifter  104  shifts a phase of the signal therethrough by +90 degrees, regardless of a direction of the signal. The phase shift of the first phase shifter  102  may be dependent on the direction of the signal therethrough. For example, the phase shifter  102  shifts a phase of a signal propagating from the first balun  110  to the balun  132  by +90 degrees, while the phase shifter  102  shifts a phase of a signal propagating from the second balun  132  to the first balun  110  by −90 degrees. 
     Accordingly, a TX signal from the TX circuit may be split by the first balun  110  into a first portion along the first path  92  and a second portion along the second path  94 . The balun causes a phase of the first portion of the TX signal along the first path  92  to be shifted +90 degrees and a phase of the second portion of the TX signal along the second path  94  to be shifted −90 degrees. The phase shifter  104  shifts a phase of the first portion of the TX signal by +90 degrees, generating a shifted first portion of the TX signal with a phase of +180 degrees. The phase shifter  102  shifts a phase of the first portion of the TX signal by an additional +90 degrees, generating a shifted first portion of the TX portion with a phase of +270 degrees. That is, the shifted first portion of the TX signal output by the phase shifter  102  is in-phase with the second portion of the TX signal along the second path  94 , since a phase of −90 degrees and a phase of +270 degrees are equivalent. Thus, the phase shifters  102 ,  104  enable the shifted first portion and the second portion of the TX signal to be constructively combined by the second balun  132  and transmitted via the one or more antennas  79 . 
     Similarly, the second balun  132  splits an RX signal received via the one or more antennas  79  into a first portion along the first path  92  and a second portion along the second path  94 . A phase of the first and second portions of the RX signal is not shifted at the second balun  132  because the portions of the RX signal are not affected by the transformer effect. That is, the phase of the first and second portions of the RX signal are 0 (zero) degrees. The phase shifter  102  shifts a phase of the first portion of the RX signal by −90 degrees and the phase shifter  104  shifts a phase of the first portion of the RX signal by +90 degrees, resulting in a phase shift to the first portion of the RX signal of 0 degrees. Thus, the phase shift provided by the phase shifter  104  counteracts the phase shift provided by the phase shifter  102 . Accordingly, the first portion of the RX signal along the first path  92  and the second portion of the RX signal along the second path  94  are in-phase at the first balun  110  (e.g., being both shifted by 0 degrees) and are constructively combined thereby. That is, the phase shifters  102 ,  104  enable the first and second portions of the RX signal to be constructively combined via the first balun  110 . 
     The impedance matching circuit  134  has an adjustable impedance to offset an imbalance between an impedance of the one or more antennas  79  and an impedance of the isolation circuit  76 . That is, the impedance matching circuit  134  may be adjusted to offset a change of an impedance of the one or more antennas  79 . For example, if the impedance of the one or more antennas  79  changes, an impedance mismatch condition may occur because the impedance of the one or more antennas  79  does not match an impedance of the isolation circuit  76 . An impedance mismatch may reduce effectiveness of the isolation of the TX and RX circuits  72 ,  74 , resulting in inferior communication quality. In that case, the impedance of the impedance matching circuit  134  may be adjusted such that the impedance mismatch condition of the one or more antennas  79  is substantially reduced. That is, the impedance of the impedance matching circuit  134  is adjusted to balance the impedance of the one or more antennas  79 . 
     Advantageously, the phase shifters  102 ,  104  enable the signals along the first path  92  and the second path  94  to be constructively combined. Combining the signals along both paths  92 ,  94  may recover power lost due to the baluns  110 ,  132 . Further, the impedance matching circuit  134  increase or maximizes the isolation between the TX circuit  72  and the RX circuit  74  by offsetting an impedance mismatch between the impedance of the one or more antennas  79  and the impedance of the isolation circuit  76 . 
       FIG.  11    is a schematic diagram of an example non-reciprocal phase shifter  102  of the transceiver circuitry  70  of  FIG.  8   , according to an embodiment of the present disclosure. The non-reciprocal phase shifter  102  may be a two-port n-path filter which includes a number (N) of capacitors  144  and transistors  142 ,  146  disposed in parallel and a phase shifter  152 . Although not shown, the non-reciprocal phase shifter  102  may be coupled to one or more local oscillators to change a frequency of a signal propagating through the non-reciprocal phase shifter  102 . In operation, the capacitors  144  may act as low-pass filters which attenuate the signals. The non-reciprocal phase shifter  102  may shift a phase of a signal from the one or more antennas  79  to the isolation circuit  76  by a first phase amount and shift a phase of a signal from the isolation circuit  76  to the one or more antennas  79  by a second phase amount different from the first phase amount. For example, as illustrated in  FIGS.  10 A- 10 C , the non-reciprocal phase shifter  102  may shift a phase of a signal from the one or more antennas  79  to the isolation circuit  76  by +90 degrees and shift a phase of a signal from the isolation circuit  76  to the one or more antennas  79  by −90 degrees. 
     Advantageously, the non-reciprocal phase shifter  102  may shift a phase of a signal therethrough without causing loss to the signal. Thus, the non-reciprocal phase shifter  102  enables the first portion of the signal therethrough to be combined with a second portion of the signal propagating along the second path  94  of the transceiver circuitry  70  discussed with respect to  FIG.  8   . 
       FIG.  12    is a schematic diagram of an example bi-directional phase shifter  104  of the transceiver circuitry  70  of  FIG.  8   , according to an embodiment of the present disclosure. As illustrated, the bi-directional phase shifter  104  includes two capacitors  162 ,  166  disposed in parallel to ground and an inductor  164  disposed between the capacitors  162 ,  166 . The bi-directional phase shifter  104  shifts a phase of a signal therethrough by an amount regardless of a direction of the signal. For example, as illustrated in  FIGS.  10 A- 10 C , the bi-directional phase shifter  104  may shift a phase of a signal from the one or more antennas  79  to the isolation circuit  76  and from the isolation circuit  76  to the one or more antennas  79  by the same amount (e.g., +90 degrees). 
     Advantageously, if the bi-directional phase shifter  104  is disposed in parallel with the non-reciprocal phase shifter  102 , the phase shift by the bi-directional phase shifter  104  enable the signals on the first path  92  and the second path  94  to be constructively combined by shifting the phase of the signal therethrough to be substantially in-phase with the shifted signal from the non-reciprocal phase shifter  102 . Similarly, if the bi-directional phase shifter  104  is disposed in series with the non-reciprocal phase shifter  102 , the phase shift of the bi-directional phase shifter  104  may increase or decrease the phase shift of the non-reciprocal phase shifter  102  such that the signals on the first path  92  and the second path  94  are substantially in-phase and can be constructively combined. 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure. 
     The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Metadata:
Filing Date: 20200924
Publication Date: 20231017
Grant Date: 20231017
Priority Date: 20200924
Inventors: HUR, JOONHOI
PRETL, HARALD
VAZNY, RASTISLAV
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L5/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/1461", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L27/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L27/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/525", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L5/1461", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/56", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L5/1461", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L27/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L27/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03H7/463", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03H7/19", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/385", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B2001/3861", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/0458", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03H7/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03H7/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L27/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L27/20", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 80473610