Diplexer circuit
A diplexer circuit is provided. The diplexer circuit, which includes a pair of hybrid couplers and a filter circuit, can be configured to support dual-connect (DC) communications on a pair of signal bands separated by a narrower transition band (e.g., ≤200 MHz). In examples discussed herein, one of the signal bands is associated with a narrower fractional bandwidth (e.g., <13%) than the other signal band. In this regard, the filter circuit can be opportunistically configured to operate based on the narrower fractional bandwidth. By configuring the filter circuit to operate based on the narrower fractional bandwidth, it is possible to eliminate the need for supporting the wider fractional bandwidth in the diplexer circuit. As a result, it may be possible to implement the diplexer circuit using conventional filters to support DC communications on signal bands associated with a wider fractional bandwidth(s) and separated by a narrower transition band.
1. A diplexer circuit comprising:
a first hybrid coupler comprising a first input port, a first isolated port, a first in-phase port, and a first quadrature port, the first hybrid coupler configured to receive and split a selected first transmit signal among a first transmit signal in a first transmit band and a second transmit signal in a second transmit band into a first in-phase transmit signal and a first quadrature transmit signal each corresponding to a first fractional bandwidth;
a second hybrid coupler comprising a second input port, a second isolated port, a second in-phase port, and a second quadrature port, the second hybrid coupler configured to receive and split a selected second transmit signal among the first transmit signal and the second transmit signal into a second in-phase transmit signal and a second quadrature transmit signal each corresponding to a second fractional bandwidth smaller than the first fractional bandwidth; and
a filter circuit coupled between the first hybrid coupler and the second hybrid coupler, the filter circuit configured to:
pass the second in-phase transmit signal and the second quadrature transmit signal to the first hybrid coupler; and
reflect the first in-phase transmit signal and the first quadrature transmit signal to the first hybrid coupler;
wherein the first hybrid coupler is further configured to output a transmit signal comprising the first transmit signal in the first transmit band and the second transmit signal in the second transmit band based on the first in-phase transmit signal, the first quadrature transmit signal, the second in-phase transmit signal, and the second quadrature transmit signal.
2. The diplexer circuit of claim 1 wherein:
the first hybrid coupler is further configured to:
receive the selected first transmit signal via the first isolated port;
output the first in-phase transmit signal and the first quadrature transmit signal via the first in-phase port and the first quadrature port, respectively; and
output the transmit signal comprising the first transmit signal in the first transmit band and the second transmit signal in the second transmit band via the first input port; and
the second hybrid coupler is further configured to:
receive the selected second transmit signal via the second input port; and
output the second in-phase transmit signal and the second quadrature transmit signal via the second in-phase port and the second quadrature port, respectively.
3. The diplexer circuit of claim 1 wherein:
the first hybrid coupler is further configured to:
receive a receive signal comprising a first receive signal in a first receive band and a second receive signal in a second receive band; and
split the receive signal into a first in-phase receive signal, a first quadrature receive signal, a second in-phase receive signal, and a second quadrature receive signal;
the filter circuit is further configured to:
reflect a selected first in-phase receive signal among the first in-phase receive signal and the second in-phase receive signal and a selected first quadrature receive signal among the first quadrature receive signal and the second quadrature receive signal to the first hybrid coupler; and
pass a selected second in-phase receive signal among the first in-phase receive signal and the second in-phase receive signal and a selected second quadrature receive signal among the first quadrature receive signal and the second quadrature receive signal to the second hybrid coupler; and
the first hybrid coupler is further configured to output a selected first receive signal based on the selected first in-phase receive signal and the selected first quadrature receive signal; and
the second hybrid coupler is further configured to output a selected second receive signal based on the selected second in-phase receive signal and the selected second quadrature receive signal.
4. The diplexer circuit of claim 3 wherein:
the first hybrid coupler is further configured to:
receive the receive signal comprising the first receive signal in the first receive band and the second receive signal in the second receive band via the first input port;
output the first in-phase receive signal and the second in-phase receive signal via the first in-phase port;
output the first quadrature receive signal and the second quadrature receive signal via the first quadrature port; and
output the selected first receive signal via the first isolated port; and
the second hybrid coupler is further configured to:
receive the second in-phase receive signal and the second quadrature receive signal via the second in-phase port and the second quadrature port, respectively; and
output the selected second receive signal via the second input port.
5. The diplexer circuit of claim 3 wherein the filter circuit comprises:
a first bandpass filter coupled between the first in-phase port and the second quadrature port, the first bandpass filter is configured to pass the second quadrature transmit signal and reject the first in-phase transmit signal; and
a second bandpass filter coupled between the first quadrature port and the second in-phase port, the second bandpass filter is configured to pass the second in-phase transmit signal and reject the first quadrature transmit signal.
6. The diplexer circuit of claim 5 wherein:
the first hybrid coupler is further configured to:
receive the first transmit signal in the first transmit band via the first isolated port;
split the first transmit signal into the first in-phase transmit signal and the first quadrature transmit signal; and
output the first in-phase transmit signal and the first quadrature transmit signal via the first in-phase port and the first quadrature port, respectively;
the second hybrid coupler is further configured to:
receive the second transmit signal in the second transmit band via the second input port;
split the second transmit signal into the second in-phase transmit signal and the second quadrature transmit signal; and
output the second in-phase transmit signal and the second quadrature transmit signal via the second in-phase port and the second quadrature port, respectively; and
the first hybrid coupler is further configured to output the transmit signal comprising the first transmit signal in the first transmit band and the second transmit signal in the second transmit band via the first input port.
7. The diplexer circuit of claim 6 wherein the first transmit band has a wider fractional bandwidth than the second transmit band.
8. The diplexer circuit of claim 6 wherein the first transmit band corresponds to fifth-generation new radio (5G-NR) band 77 and the second transmit band corresponds to 5G-NR band 79.
9. The diplexer circuit of claim 5 wherein:
the first bandpass filter is further configured to pass the second in-phase receive signal and reject the first in-phase receive signal; and
the second bandpass filter is further configured to pass the second quadrature receive signal and reject the first quadrature receive signal.
10. The diplexer circuit of claim 9 wherein:
the first hybrid coupler is further configured to:
receive the receive signal comprising the first receive signal in the first receive band and the second receive signal in the second receive band via the first input port;
split the receive signal into the first in-phase receive signal, the first quadrature receive signal, the second in-phase receive signal, and the second quadrature receive signal;
output the first in-phase receive signal and the second in-phase receive signal via the first in-phase port;
output the first quadrature receive signal and the second quadrature receive signal via the first quadrature port; and
output the first receive signal via the first isolated port; and
the second hybrid coupler is further configured to:
receive the second in-phase receive signal and the second quadrature receive signal via the second quadrature port and the second in-phase port, respectively; and
output the second receive signal via the second input port.
11. The diplexer circuit of claim 10 wherein the first receive band has a wider fractional bandwidth than the second receive band.
12. The diplexer circuit of claim 10 wherein the first transmit band corresponds to fifth-generation new radio (5G-NR) band 77 and the second transmit band corresponds to 5G-NR band 79.
13. The diplexer circuit of claim 3 wherein the filter circuit comprises:
a first bandstop filter coupled between the first in-phase port and the second quadrature port, the first bandstop filter is configured to stop the second in-phase receive signal and pass the first quadrature receive signal; and
a second bandstop filter coupled between the first quadrature port and the second in-phase port, the second bandstop filter is configured to pass the first in-phase receive signal and reject the second quadrature receive signal.
14. The diplexer circuit of claim 13 wherein:
the first hybrid coupler is further configured to:
receive the second transmit signal in the second transmit band via the first isolated port;
split the second transmit signal into the second in-phase transmit signal and the second quadrature transmit signal; and
output the second in-phase transmit signal and the second quadrature transmit signal via the first in-phase port and the first quadrature port, respectively;
the second hybrid coupler is further configured to:
receive the first transmit signal in the first transmit band via the second input port;
split the first transmit signal into the first in-phase transmit signal and the first quadrature transmit signal; and
output the first in-phase transmit signal and the first quadrature transmit signal via the second in-phase port and the second quadrature port, respectively; and
the first hybrid coupler is further configured to output the transmit signal comprising the first transmit signal in the first transmit band and the second transmit signal in the second transmit band via the first input port.
15. The diplexer circuit of claim 14 wherein the second transmit band corresponds to a wider fractional bandwidth than the first transmit band.
16. The diplexer circuit of claim 15 wherein the first transmit band corresponds to fifth-generation new radio (5G-NR) band 79 and the second transmit band corresponds to 5G-NR band 77.
17. The diplexer circuit of claim 13 wherein:
the first bandstop filter is further configured to pass the first in-phase receive signal and reject the second in-phase receive signal; and
the second bandstop filter is further configured to pass the first quadrature receive signal and reject the second quadrature receive signal.
18. The diplexer circuit of claim 17 wherein:
the first hybrid coupler is further configured to:
receive the receive signal comprising the first receive signal in the first receive band and the second receive signal in the second receive band via the first input port;
split the receive signal into the first in-phase receive signal, the first quadrature receive signal, the second in-phase receive signal, and the second quadrature receive signal;
output the first in-phase receive signal and the second in-phase receive signal via the first in-phase port;
output the first quadrature receive signal and the second quadrature receive signal via the first quadrature port; and
output the second receive signal via the first isolated port; and
the second hybrid coupler is further configured to:
receive the first in-phase receive signal and the first quadrature receive signal via the second quadrature port and the second in-phase port, respectively; and
output the first receive signal via the second input port.
19. The diplexer circuit of claim 18 wherein the second receive band corresponds to a wider fractional bandwidth than the first receive band.
20. The diplexer circuit of claim 18 wherein the first transmit band corresponds to fifth-generation new radio (5G-NR) band 79 and the second transmit band corresponds to 5G-NR band 77.
21. The diplexer circuit of claim 1 further comprising a switching circuit coupled between the first hybrid coupler and the filter circuit, the switching circuit is configured to bypass the filter circuit and the second hybrid coupler.
22. The diplexer circuit of claim 21 wherein the switching circuit comprises a first shunt switch and a second shunt switch configured to form a pair of shunt paths between the first in-phase port and the first quadrature port and a ground, respectively.
23. The diplexer circuit of claim 21 wherein the switching circuit comprises a first switch and a second switch configured to:
couple the first in-phase port and the first quadrature port to the filter circuit, respectively; and
decouple the first in-phase port and the first quadrature port from the filter circuit, respectively.
24. An apparatus comprising:
a transceiver circuit configured to generate a first transmit signal in a first transmit band and a second transmit signal in a second transmit band; and
a diplexer circuit comprising:
a first hybrid coupler comprising a first input port, a first isolated port, a first in-phase port, and a first quadrature port, the first hybrid coupler configured to receive and split a selected first transmit signal among the first transmit signal and the second transmit signal into a first in-phase transmit signal and a first quadrature transmit signal each corresponding to a first fractional bandwidth;
a second hybrid coupler comprising a second input port, a second isolated port, a second in-phase port, and a second quadrature port, the second hybrid coupler configured to receive and split a selected second transmit signal among the first transmit signal and the second transmit signal into a second in-phase transmit signal and a second quadrature transmit signal each corresponding to a second fractional bandwidth smaller than the first fractional bandwidth; and
a filter circuit coupled between the first hybrid coupler and the second hybrid coupler, the filter circuit configured to:
pass the second in-phase transmit signal and the second quadrature transmit signal to the first hybrid coupler; and
reflect the first in-phase transmit signal and the first quadrature transmit signal to the first hybrid coupler; and
wherein the first hybrid coupler is further configured to output a transmit signal comprising the first transmit signal in the first transmit band and the second transmit signal in the second transmit band based on the first in-phase transmit signal, the first quadrature transmit signal, the second in-phase transmit signal, and the second quadrature transmit signal.
25. The apparatus of claim 24 wherein:
the first hybrid coupler is further configured to:
receive a receive signal comprising a first receive signal in a first receive band and a second receive signal in a second receive band; and
split the receive signal into a first in-phase receive signal, a first quadrature receive signal, a second in-phase receive signal, and a second quadrature receive signal;
the filter circuit is further configured to:
reflect a selected first in-phase receive signal among the first in-phase receive signal and the second in-phase receive signal and a selected first quadrature receive signal among the first quadrature receive signal and the second quadrature receive signal to the first hybrid coupler; and
pass a selected second in-phase receive signal among the first in-phase receive signal and the second in-phase receive signal and a selected second quadrature receive signal among the first quadrature receive signal and the second quadrature receive signal to the second hybrid coupler; and
the first hybrid coupler is further configured to output a selected first receive signal based on the selected first in-phase receive signal and the selected first quadrature receive signal;
the second hybrid coupler is further configured to output a selected second receive signal based on the selected second in-phase receive signal and the selected second quadrature receive signal; and
the transceiver circuit is further configured to receive the selected first receive signal and the selected second receive signal from the first hybrid coupler and the second hybrid coupler, respectively.
26. The apparatus of claim 25 wherein:
the filter circuit comprises:
a first bandpass filter coupled between the first in-phase port and the second quadrature port, the first bandpass filter is configured to:
pass the second quadrature transmit signal and reject the first in-phase transmit signal; and
pass the second in-phase receive signal and reject the first in-phase receive signal; and
a second bandpass filter coupled between the first quadrature port and the second in-phase port, the second bandpass filter is configured to:
pass the second in-phase transmit signal and reject the first quadrature transmit signal; and
pass the second quadrature receive signal and reject the first quadrature receive signal; and
the transceiver circuit is further configured to:
provide the first transmit signal and the second transmit signal to the first isolated port and the second input port, respectively; and
receive the first receive signal and the second receive signal from the first isolated port and the second input port, respectively.
27. The apparatus of claim 26 wherein:
the first transmit band has a wider fractional bandwidth than the second transmit band; and
the first receive band has a wider fractional bandwidth than the second receive band.
28. The apparatus of claim 25 wherein the filter circuit comprises:
a first bandstop filter coupled between the first in-phase port and the second quadrature port, the first bandstop filter is configured to:
stop the second in-phase receive signal and pass the first quadrature receive signal; and
pass the first in-phase receive signal and reject the second in-phase receive signal; and
a second bandstop filter coupled between the first quadrature port and the second in-phase port, the second bandstop filter is configured to:
pass the first in-phase receive signal and reject the second quadrature receive signal; and
pass the first quadrature receive signal and reject the second quadrature receive signal; and
the transceiver circuit is further configured to:
provide the second transmit signal and the first transmit signal to the first isolated port and the second input port, respectively; and
receive the second receive signal and the first receive signal from the first isolated port and the second input port, respectively.
29. The apparatus of claim 28 wherein:
the second transmit band corresponds to a wider fractional bandwidth than the first transmit band; and
the second receive band corresponds to a wider fractional bandwidth than the first receive band.
30. The apparatus of claim 24 wherein the diplexer circuit further comprises a switching circuit coupled between the first hybrid coupler and the filter circuit, the switching circuit is configured to bypass the filter circuit and the second hybrid coupler.
31. The apparatus of claim 30 wherein the switching circuit comprises a first shunt switch and a second shunt switch configured to form a pair of shunt paths between the first in-phase port and the first quadrature port and a ground, respectively.
32. The apparatus of claim 30 wherein the switching circuit comprises a first switch and a second switch configured to:
couple the first in-phase port and the first quadrature port to the filter circuit, respectively; and
decouple the first in-phase port and the first quadrature port from the filter circuit, respectively.