RF switch

1. An RF switch for connecting an antenna to a transceiver, the RF switch comprising a first switchable capacitor arranged between a first terminal and a common terminal and a second switchable capacitor arranged between a second terminal and the common terminal, wherein each of the first and second switchable capacitors are switchable between a pass state and a blocking state wherein the capacitance value in the pass state is higher than the capacitance value in the blocking state, wherein the RF switch further comprises a bias circuit having a control input and configured to bias the switchable capacitors in either the blocking state or the pass state in response to a control signal in the control input, the RF switch further comprising a first resonator circuit coupled to the first terminal, a second resonator circuit coupled to the second terminal and a third resonator coupled to the common terminal wherein the impedance of each resonator circuit is higher at RF frequencies than at DC.

2. The RF switch of claim 1 wherein the first, second and third resonator circuits are coupled to the bias circuit.

3. The RF switch of claim 1 wherein the first, second and third resonator circuits comprise self-resonating coils.

4. The RF switch of claim 1 wherein the first and second switchable capacitor each comprise one of a diode-connected bipolar transistor, silicon diode, a silicon germanium diode, a PiN diode, and a varicap.

5. The RF switch of claim 1 configured as a SPDT switch wherein the common terminal is configured to be coupled to an antenna, the first terminal is configured to be coupled to an RF amplifier output and the second terminal is configured to be coupled to an RF amplifier input and wherein a first mode one of the first terminal and the second terminal is coupled to the common terminal and in a second mode the other of the first terminal and the second terminal is coupled to the common terminal.

6. The RF switch of claim 1 wherein the bias circuit is configured to supply a bias forward current to a respective switchable capacitor in the pass state and a reverse bias voltage to a respective switchable capacitor in the blocking state.

7. An RF switch for connecting an antenna to a transceiver, the RF switch comprising a first switchable capacitor arranged between a first terminal and a common terminal and a second switchable capacitor arranged between a second terminal and the common terminal, wherein each of the first and second switchable capacitors are switchable between a pass state and a blocking state wherein the capacitance value in the pass state is higher than the capacitance value in the blocking state, wherein the RF switch further comprises a bias circuit having a control input and configured to bias the switchable capacitors in either the blocking state or the pass state in response to a control signal in the control input, wherein the bias circuit is configured to supply a bias forward current to a respective switchable capacitor in the pass state and a reverse bias voltage to a respective switchable capacitor in the blocking state.

8. An RF switch of claim 7 wherein the first and second switchable capacitor each comprise one of a diode-connected bipolar transistor, silicon diode, a silicon germanium diode, a PiN diode, and a varicap.

9. A mobile device comprising the RF switch of claim 7 .

10. A 5G transceiver comprising the RF switch of claim 7 .

11. The RF switch of claim 7 configured as a SPDT switch wherein the common terminal is configured to be coupled to an antenna, the first terminal is configured to be coupled to an RF amplifier output and the second terminal is configured to be coupled to an RF amplifier input and wherein a first mode one of the first terminal and the second terminal is coupled to the common terminal and in a second mode the other of the first terminal and the second terminal is coupled to the common terminal.

12. An RF switch for connecting an antenna to a transceiver, the RF switch comprising a first switchable capacitor arranged between a first terminal and a common terminal and a second switchable capacitor arranged between a second terminal and the common terminal, wherein each of the first and second switchable capacitors are switchable between a pass state and a blocking state wherein the capacitance value in the pass state is higher than the capacitance value in the blocking state, wherein the RF switch further comprises a bias circuit having a control input and configured to bias the switchable capacitors in either the blocking state or the pass state in response to a control signal in the control input, wherein the bias circuit comprises a power-dependent adaptive current source configured to supply a bias forward current in dependence of the power of the RF signal.

13. An RF switch for connecting an antenna to a transceiver, the RF switch comprising a first switchable capacitor arranged between a first terminal and a common terminal and a second switchable capacitor arranged between a second terminal and the common terminal, wherein each of the first and second switchable capacitors are switchable between a pass state and a blocking state wherein the capacitance value in the pass state is higher than the capacitance value in the blocking state, wherein the RF switch further comprises a bias circuit having a control input and configured to bias the switchable capacitors in either the blocking state or the pass state in response to a control signal in the control input, wherein the bias circuit comprises a first switchable current source coupled to the first terminal, a first switchable voltage source coupled to the first terminal, a second switchable current source coupled to the second terminal, a second switchable voltage source coupled to the second terminal, and a common switchable voltage source coupled to the common terminal, wherein in a first mode of operation, the RF switch is configured to enable the first switchable current source, the second switchable voltage source and the common switchable voltage source to configure the first switchable capacitor in a pass-state and the second switchable capacitor in a blocking-state and in a second mode of operation to enable the second switchable current source, the first switchable voltage source and the common switchable voltage source to configure the first switchable capacitor in a blocking-state and the second switchable capacitor in a pass-state.

14. The RF switch of claim 13 wherein each of the first and second switchable capacitors comprises a respective bipolar transistor having a base connected to the emitter and wherein the collector of the first bipolar transistor and the emitter of the second bipolar transistor are connected to the common terminal.

15. The RF switch of claim 13 wherein the first and second switchable capacitor each comprise one of a diode-connected bipolar transistor, silicon diode, a silicon germanium diode, a PiN diode, and a varicap.

16. A mobile device comprising the RF switch of claim 13 .

17. A 5G transceiver comprising the RF switch of claim 13 .

18. An RF switch for connecting an antenna to a transceiver, the RF switch comprising a first switchable capacitor arranged between a first terminal and a common terminal and a second switchable capacitor arranged between a second terminal and the common terminal, wherein each of the first and second switchable capacitors are switchable between a pass state and a blocking state wherein the capacitance value in the pass state is higher than the capacitance value in the blocking state, wherein the RF switch further comprises a bias circuit having a control input and configured to bias the switchable capacitors in either the blocking state or the pass state in response to a control signal in the control input, wherein the bias circuit comprises a current source coupled to the common terminal, a first switchable voltage source coupled to the first terminal, and a second switchable voltage source coupled to the second terminal, wherein in a first mode of operation, the RF switch is configured to enable the first switchable voltage source, the second switchable voltage source to configure the first switchable capacitor in a pass state and the second switchable capacitor in a blocking state and in a second mode of operation to enable the first switchable voltage source and the second switchable voltage source to configure the first switchable capacitor in a blocking state and the second switchable capacitor in a pass state.

19. The RF switch of claim 18 wherein each of the first and second switchable capacitors comprises a respective bipolar transistor having a base connected to the emitter, and wherein the emitter of the first bipolar transistor and the emitter of the second bipolar transistor are connected to the common terminal.

20. A mobile device comprising the RF switch of claim 18 .