RF branch with improved power handling
Improved Radio Frequency (RF) switches are provided herein. According to one aspect, an RF switch comprises one or more stages. In one embodiment, each stage comprises a signal input terminal, a signal output terminal, a control input terminal, and a switching device having a source connected to the signal input terminal, a drain connected to the signal output terminal, a gate for controlling the on/off state of the switching device, and a body terminal. Each stage includes a gate resistor connected in series between the control input terminal and the gate and a rectification circuit for rectifying a voltage across the source and drain to provide a local bias voltage to the body terminal.
1. A radio frequency (RF) switch, comprising:
one or more stages, each stage comprising:
a signal input terminal;
a signal output terminal;
a control input terminal;
a switching device having a source terminal connected to the signal input terminal, a drain terminal connected to the signal output terminal, a gate terminal for controlling an on/off state of the switching device, and a body terminal;
a gate resistor connected in series between the control input terminal and the gate terminal, wherein the gate resistor of each stage forms part of a gate bias network; and
a rectification circuit for rectifying a voltage across the source and drain terminals to provide a local bias voltage to the body terminal, wherein the rectification circuit comprises:
a first capacitor connected between the source terminal and a first intermediate node;
a first diode having an anode connected to the first intermediate node and a cathode connected to the drain terminal;
a second capacitor connected between the drain terminal and a second intermediate node; and
a second diode having an anode connected to the second intermediate node and a cathode connected to the source terminal.
2. The switch of claim 1 wherein the switching device of at least one stage comprises a Field-Effect Transistor (FET).
3. The switch of claim 1 wherein for at least one stage, the rectification circuit comprises:
a first resistor connected in series between the first intermediate node and the body terminal; and
a second resistor connected in series between the second intermediate node and the body terminal.
4. The switch of claim 1 wherein at least one stage further comprises a first bypass switch for connecting each terminal of the gate resistor to bypass the gate resistor when the first bypass switch is closed.
5. The switch of claim 4 wherein the first bypass switch operates to bypass the gate resistor when the switching device is in the on state and does not operate to bypass the gate resistor when the switching device is in the off state.
6. The switch of claim 4 wherein the first bypass switch comprises one or more switching devices in series.
7. The switch of claim 6 wherein at least one stage further comprises at least one varactor connected in series between each terminal of the gate resistor.
8. The switch of claim 1 wherein at least one stage further comprises a first body switch for connecting the source terminal to the body terminal when closed and a second body switch for connecting the drain terminal to the body terminal when closed.
9. The switch of claim 8 wherein the first body switch or the second body switch comprises one or more switching devices in series.
10. The switch of claim 8 wherein at least one stage further comprises a third body switch for connecting the gate terminal to the body terminal when closed.
11. The switch of claim 10 wherein the third body switch comprises one or more switching devices in parallel.
12. The switch of claim 1 wherein at least one stage further comprises at least one diode connected in series between the source terminal or drain terminal and the body terminal to provide a discharge path from the source terminal or the drain terminal to the body terminal.
13. The switch of claim 1 wherein at least one stage further comprises a body bias input terminal and a body resistor connected in series between the body bias input terminal and the body terminal of the switching device, the body resistor of each stage forming a body bias network.
14. The switch of claim 1 comprising a plurality of stages, wherein the switching devices of the plurality of stages are connected in series.
15. The switch of claim 1 wherein each stage further comprises a source-drain resistor connected in series between the source terminal and the drain terminal, the one or more source-drain resistors forming a source-drain bias network.
16. The switch of claim 15 wherein at least one stage further comprises a second bypass switch for connecting each end of the source-drain resistor to bypass the source-drain resistor when the second bypass switch is closed.
17. The switch of claim 16 wherein the second bypass switch operates to bypass the source-drain resistor when the switching device is in the on state and does not operate to bypass the source-drain transistor when the switching device is in the off state.
18. The switch of claim 16 wherein the second bypass switch comprises one or more switching devices in series.
19. A radio frequency (RF) switch, comprising:
one or more stages, each stage comprising:
a signal input terminal;
a signal output terminal;
a control input terminal;
a switching device having a source terminal connected to the signal input terminal, a drain terminal connected to the signal output terminal, a gate terminal for controlling an on/off state of the switching device, and a body terminal;
a gate resistor connected in series between the control input terminal and the gate terminal, wherein the gate resistor of each stage forms part of a gate bias network; and
a rectification circuit for rectifying a voltage across the source and drain terminals to provide a local bias voltage to the body terminal, wherein the rectification circuit comprises:
a first capacitor connected between the source terminal and a first intermediate node;
a first diode-connected field-effect transistor (DFET) having a gate terminal and a drain terminal connected to the first intermediate node and a source terminal connected to the drain terminal of the switching device;
a second capacitor connected between the drain terminal and a second intermediate node; and
a second DFET having a gate terminal and a drain terminal connected to the second intermediate node and a source terminal connected to the source terminal of the switching device.
20. The switch of claim 19 , wherein the rectification circuit further comprises:
a first resistor connected in series between the first intermediate node and the body terminal; and
a second resistor connected in series between the second intermediate node and the body terminal.
21. A radio frequency (RF) switch, comprising:
one or more stages, each stage comprising:
a signal input terminal;
a signal output terminal;
a control input terminal;
a switching device having a source terminal connected to the signal input terminal, a drain terminal connected to the signal output terminal, a gate terminal for controlling an on/off state of the switching device, and a body terminal;
a gate resistor connected in series between the control input terminal and the gate terminal, wherein the gate resistor of each stage forms part of a gate bias network; and
a rectification circuit for rectifying a voltage across the source and drain terminals to provide a local bias voltage to the body terminal, wherein the rectification circuit comprises:
a first varactor connected between the source terminal and a first intermediate node;
a first diode-connected field-effect transistor (DFET) having a gate terminal and a drain terminal connected to the first intermediate node and a source terminal connected to the drain terminal of the switching device;
a second varactor connected between the drain terminal and a second intermediate node;
a second DFET having a gate terminal and a drain terminal connected to the second intermediate node and a source terminal connected to the source terminal of the switching device; and
a first capacitor connected between the first intermediate node and the second intermediate node.
22. The switch of claim 21 , wherein the rectification circuit further comprises:
a first resistor connected in series between the first intermediate node and the body terminal; and
a second resistor connected in series between the second intermediate node and the body terminal.