Radio frequency switch
A radio frequency switch having an N number of switch cells coupled in series is disclosed. Each of the switch cells includes a field-effect transistor (FET), wherein a source of switch cell 1 is coupled to a first port, a drain of switch cell N is coupled to a second port, and a drain of switch cell X is coupled to a source of switch cell X+1 for switch cell 1 through switch cell N. A first diode stack has a first anode coupled to the body of switch cell X and a first cathode coupled to a drain of switch cell X+1 for switch cell 1 through switch cell N−1, and a second diode stack has a second anode coupled to the body of switch cell X and a second cathode coupled to the source of switch cell X−1 for switch cell 2 through switch cell N.
1. A radio frequency switch comprising a first port, a second port, and an N number of switch cells coupled in series between the first port and the second port, wherein N is a counting number greater than 1 and each of the N number of switch cells comprises:
a field-effect transistor (FET) comprising a source, a drain, a gate, and a body, wherein the source of switch cell 1 is coupled to the first port, the drain of switch cell N is coupled to the second port, and the drain of switch cell X is coupled to the source of switch cell X+1 for switch cell 1 through switch cell N, wherein X is a counting number;
a first diode stack having a first anode coupled to the body of switch cell X and a first cathode coupled to the drain of switch cell X+1 for switch cell 1 through switch cell N−1; and
a second diode stack having a second anode coupled to the body of switch cell X and a second cathode coupled to the source of switch cell X−1 for switch cell 2 through switch cell N.
2. The radio frequency switch of claim 1 further comprising a first port diode stack coupled in parallel with the first diode stack of switch cell 1 and a second port diode stack coupled in parallel with the second diode stack of switch cell N.
3. The radio frequency switch of claim 1 wherein the first diode stack and the second diode stack each comprise at least two diodes coupled in series anode to cathode.
4. The radio frequency switch of claim 1 wherein each switch cell further comprises an auxiliary body switch coupled between the gate and body.
5. The radio frequency switch of claim 1 further comprising a gate bias network coupled to the gate of each FET of the N number of switch cells.
6. The radio frequency switch of claim 5 further including a first-end varactor that is configured to provide symmetric impedance to the first port and is coupled between the gate bias network and the first port.
7. The radio frequency switch of claim 6 further including a second-end varactor that is configured to provide symmetric impedance to the second port and is coupled between the gate bias network and the second port.
8. The radio frequency switch of claim 1 further comprising a body bias network coupled to the body of each FET of the N number of switch cells.
9. The radio frequency switch of claim 1 wherein each switch cell further comprises a drain-to-source resistor coupled between the source and drain of the FET.
10. The radio frequency switch of claim 1 wherein each switch cell further comprises an off-state linearization network coupled between the source and drain of the FET.
11. The radio frequency switch of claim 10 wherein the off-state linearization network of each switch cell comprises:
a first varactor coupled between a tuning node and the source of the FET; and
a second varactor coupled between the tuning node and the drain of the FET.
12. The radio frequency switch of claim 11 wherein each switch cell further comprises a tuner biasing diode coupled having an anode coupled to the body of the FET and a cathode coupled to the tuning node between the first varactor and the second varactor.
13. The radio frequency switch of claim 11 wherein the first varactor and the second varactor are both inversion-mode type varactor diodes.
14. The radio frequency switch of claim 11 wherein the first varactor and the second varactor are both accumulation-mode type diodes.