Differential duplexer systems with phase shifters
A communication device includes a duplexer differentially coupled to a receiver and a transmitter. The duplexer may include phase shifters on the differential lines to provide differential received signals to the receiver and receive differential transmission signals from the transmitter for transmission. For example, the phase shifter are positioned such that single-ended received signals may be converted to differential received signals and convert the differential transmission signals to single-ended transmission signals for transmission. Moreover, the phase shifters may provide the single-ended transmission signals to antennas for transmission and to the differential lines of the receiver for cancellation/isolation. Furthermore, the phase shifters may provide the differential received signals to the receiver for reception and provide the single-ended received signals to the differential lines of the transmitter for cancellation/isolation. Accordingly, the duplexer may convey communication signal while reducing signal interference by providing improved isolation.
1 . A radio frequency front end (RFFE) circuit, comprising:
a first phase shifter coupled to one or more antennas and configured to shift a phase of a receive signal within a receive frequency range received by the one or more antennas to generate a phase-shifted receive signal and pass-through a transmission signal within a transmission frequency range;
a second phase shifter coupled to the one or more antennas and configured to shift a phase of the transmission signal to generate a phase-shifted transmission signal and pass-through the receive signal;
a receiver differentially coupled to the first phase shifter and the one or more antennas and configured to receive the phase-shifted receive signal and the receive signal, the transmission signal and the phase-shifted transmission signal destructively combining at the receiver; and
a transmitter differentially coupled to the second phase shifter and the one or more antennas, the transmitter configured to output the transmission signal, the receive signal and the phase-shifted receive signal destructively combining at the transmitter.
2 . The RFFE circuit of claim 1 , comprising a first balun differentially coupling the receiver to the first phase shifter and the one or more antennas.
3 . The RFFE circuit of claim 2 , wherein the first balun is configured to constructively combine in-phase signals received from the first phase shifter and the one or more antennas.
4 . The RFFE circuit of claim 2 , wherein the first balun is configured to destructively combine out-of-phase signals received from the first phase shifter and the one or more antennas.
5 . The RFFE circuit of claim 1 , comprising a second balun differentially coupling the transmitter to the second phase shifter and the one or more antennas.
6 . The RFFE circuit of claim 5 , wherein the second balun is configured to provide in-phase signals to the second phase shifter and the one or more antennas based on receiving single-ended signals from the transmitter.
7 . The RFFE circuit of claim 6 , wherein the second balun is configured to destructively combine out-of-phase signals received from the second phase shifter and the one or more antennas.
8 . The RFFE circuit of claim 1 , comprising a first impedance tuner coupled to the first phase shifter and the one or more antennas, the first impedance tuner configured to provide a first impedance higher than a first threshold impedance to input signals having a frequency within the receive frequency range and provide a second impedance lower than a second threshold impedance to input signals having a frequency within the transmission frequency range.
9 . The RFFE circuit of claim 8 , comprising a second impedance tuner coupled to the second phase shifter and the one or more antennas, the second impedance tuner configured to provide a third impedance higher than a third threshold impedance to input signals having a frequency within the transmission frequency range and provide a fourth impedance lower than a fourth threshold impedance to input signals having a frequency within the receive frequency range.
10 . A duplexer, comprising:
a receiver phase shifter having a first terminal coupled to differential receiver circuitry and a second terminal coupled to the differential receiver circuitry and an antenna, the receiver phase shifter configured to shift a phase of a receive signal within a receive frequency range received by the antenna to generate a phase-shifted receive signal and pass-through a transmission signal within a transmission frequency range, the differential receiver circuitry configured to receive the phase-shifted receive signal and the receive signal; and
a transmitter phase shifter having a first terminal coupled to differential transmitter circuitry and a second terminal coupled to the differential transmitter circuitry and the antenna, the transmitter phase shifter configured to shift a phase of the transmission signal to generate a phase-shifted transmission signal and pass-through the receive signal, the differential transmitter circuitry configured to output the transmission signal, the receive signal and the phase-shifted receive signal destructively combining at the differential transmitter circuitry, and the transmission signal and the phase-shifted transmission signal destructively combining at the differential receiver circuitry.
11 . The duplexer of claim 10 , wherein the receiver phase shifter is configured to
provide differential signals having a frequency within the receive frequency range, and
provide two in-phase signals having a frequency within the transmission frequency range.
12 . The duplexer of claim 10 , wherein the transmitter phase shifter is configured to
provide differential signals having a frequency within the transmission frequency range, and
provide two in-phase signals having a frequency within the receive frequency range.
13 . The duplexer of claim 10 , comprising a receiver impedance tuner coupled to the receiver phase shifter and the antenna.
14 . The duplexer of claim 13 , comprising a transmitter impedance tuner coupled to the transmitter phase shifter and the antenna.
15 . The duplexer of claim 14 , wherein the receiver impedance tuner is configured to provide a first impedance higher than a first threshold to the phase-shifted receive signal and provide a second impedance lower than a second threshold to the transmission signal.
16 . The duplexer of claim 15 , wherein the transmitter impedance tuner is configured to provide a third impedance higher than the first threshold to the transmission signal and provide a fourth impedance lower than the second threshold to the phase-shifted receive signal.
17 . An electronic device, comprising:
a radio frequency (RF) receiver;
a first balun coupled to the RF receiver;
an RF transmitter;
a second balun coupled to the RF transmitter; and
a duplexer coupled to one or more antennas, the duplexer being differentially coupled to the RF receiver via the first balun and differentially coupled to the RF transmitter via the second balun, the duplexer comprising
a first phase shifter configured to shift a phase of a receive signal within a receive frequency range to generate a phase-shifted receive signal and pass-through a transmission signal within a transmission frequency range, the RF receiver configured to receive the phase-shifted receive signal and the receive signal, and
a second phase shifter configured to shift a phase of the transmission signal to generate a phase-shifted transmission signal and pass-through the receive signal, the RF transmitter configured to output the transmission signal, the receive signal and the phase-shifted receive signal destructively combining at the RF transmitter, and the transmission signal and the phase-shifted transmission signal destructively combining at the RF receiver.
18 . The electronic device of claim 17 , wherein the second balun is configured to destructively combine out-of-phase signals received from the duplexer.
19 . The electronic device of claim 17 , wherein the first balun is configured to
constructively combine in-phase signals received from the duplexer, and
destructively combine out-of-phase signals received from the duplexer.
20 . The electronic device of claim 17 , wherein the second balun is configured to
provide two in-phase signals to the duplexer based on receiving a single-ended signal from the RF transmitter.