Transmission-line-based radio-frequency switching
Radio-frequency core circuitry includes a first switch arm associated with a first signal band and coupled to a common node, a second switch arm associated with a second signal band and coupled to the common node, a first shunt arm connected to a first shunt node in the first switch arm, and a first transmission line disposed in the first switch arm between the common node and the shunt node and having a length configured present an open circuit at a fundamental frequency associated with the second signal band and to present a short circuit at a harmonic of the fundamental frequency associated with the second signal band.
1. Radio-frequency core circuitry comprising:
a first switch arm coupled to a common node and configured to transmit a first signal having a first wavelength λ1;
a second switch arm coupled to the common node and configured to transmit a second signal having a second wavelength λ2;
a first shunt arm connected to a first shunt node in the first switch arm;
a second shunt arm connected to a second shunt node in the second switch arm;
a first transmission line disposed in the first switch arm between the common node at a first end of the first transmission line and the first shunt node at a second end of the first transmission line, the first transmission line having a length of M*¼λ2, M being an integer; and
a second transmission line disposed in the second switch arm between the common node at a first end of the second transmission line and the second shunt node at a second end of the second transmission line, the second transmission line having a length of N*¼λ1, N being an integer.
2. The radio-frequency core circuitry of claim 1 wherein the first shunt arm includes a tank circuit configured to resonate at a harmonic of the second signal band.
3. The radio-frequency core circuitry of claim 2 wherein the first shunt arm further includes a switch connected in series with the tank circuit.
4. The radio-frequency core circuitry of claim 1 wherein the first switch arm does not include a series switch between the common node and the first shunt node.
5. The radio-frequency core circuitry of claim 1 wherein is configured to present an open circuit at a fundamental frequency associated with the first signal and to present a short circuit at a harmonic of the fundamental frequency associated with the first signal.
6. The radio-frequency core circuitry of claim 1 wherein the first shunt arm is connected to a plurality of transmission paths in parallel, each of the plurality of transmission paths including a switch for transmitting a signal corresponding to a different frequency band.
7. A method of transmitting a radio-frequency signal comprising:
transmitting a first signal on a first switch arm to a common node coupled to both the first switch arm and to a second switch arm, the first signal having a first fundamental frequency associated with a first wavelength λ1;
filtering out a harmonic of the first fundamental frequency of the first signal using a first transmission line disposed in the second switch arm between the common node at a first end of the first transmission line and, at a second end of the first transmission line, a first shunt arm connected to the second switch arm, the first transmission line having a length of M*¼λ1 and configured present an open circuit at the first fundamental frequency and to present a short circuit at the harmonic of the first fundamental frequency, M being an integer;
transmitting a second signal on the second switch arm, the second signal having a second fundamental frequency associated with a second wavelength λ2;
filtering out a harmonic of the second fundamental frequency of the second signal using a second transmission line disposed in the first switch arm between the common node at a first end of the second transmission line and, at a second end of the second transmission line, a second shunt arm connected to the first switch arm, the second transmission line having a length of N*¼λ2 and configured to present an open circuit at the second fundamental frequency and to present a short circuit at the harmonic of the second fundamental frequency, N being an integer;
transmitting the first signal using an antenna communicatively coupled to the common node; and
transmitting the second signal using the antenna.
8. The method of claim 7 further comprising resonating a tank circuit at the harmonic of the first fundamental frequency, the tank circuit being disposed in the first shunt arm.
9. The method of claim 8 wherein the second switch arm does not include a series switch between the common node and the first shunt arm.
10. The method of claim 7 wherein M is equal to 1.
11. The method of claim 10 wherein N is equal to 3.
12. Electronic circuitry comprising:
a first switch arm configured for transmission of signals in a first signal band associated with a first wavelength λ1, the first switch arm being coupled to a common node;
a second switch arm configured for transmission of signals in a second signal band and coupled to the common node;
a first shunt arm connected to a first shunt node in the first switch arm;
a second shunt arm connected to a second shunt node to a second shunt node in the second switch arm;
a first transmission line disposed in the first switch arm between the common node at a first end of the first transmission line and the first shunt node at a second end of the first transmission line, the first transmission line having a length of M*¼λ2 and being configured present an open circuit at a fundamental frequency associated with the second signal band and to present a short circuit at a harmonic of the fundamental frequency associated with the second signal band, M being an integer; and
a second transmission line disposed in the second switch arm between the common node at a first end of the second transmission line and the second shunt node at a second end of the second transmission line, the second transmission line having a length of N*¼λ1 and being configured to present an open circuit at a fundamental frequency associated with the first signal band and to present a short circuit at a harmonic of the fundamental frequency associated with the first signal band, N being an integer.
13. The electronic circuitry of claim 12 wherein the first shunt arm includes a tank circuit configured to resonate at the harmonic of the fundamental frequency associated with the second signal band.
14. The electronic circuitry of claim 12 wherein the first switch arm does not include a series switch between the common node and the first shunt node.
15. The electronic circuitry of claim 12 wherein M is equal to 3.
16. The electronic circuitry of claim 12 wherein N is equal to 1.