Method and apparatus for a dynamically self-bootstrapped switch
A dynamically self-bootstrapping circuit for a switch features a resistor in series with the control node of the switch. A bypass switch connects a control node to ground. When the switch is in an off-state, the bypass switch is enabled.
1. A dynamically self-bootstrapping circuit for a switch comprising:
a first resistor connecting a control node of the switch to a switch control input;
a first bypass switch connecting the control node of the switch to ground;
a first bypass switch resistor in series with a gate node of the first bypass switch; and
a second bypass switch resistor in series with a back gate node of the first bypass switch, the first and second bypass switch resistors self-bootstrapping the first bypass switch,
wherein the first bypass switch is disabled when the switch is in an on-state and enabled when the switch is in an off-state.
2. The circuit of claim 1 , wherein the switch is an FET switch and the control node is a gate node of the FET switch.
3. The circuit of claim 2 , further comprising:
a second resistor connecting a back gate node of the FET switch to ground; and
a second bypass switch connecting the back gate node of the FET switch to ground,
wherein the second bypass switch is disabled when the FET switch is in an on-state, and enabled when the FET switch is in an off-state.
4. The circuit of claim 3 , further comprising:
a third bypass switch resistor in series with a gate node of the second bypass switch; and
a fourth bypass switch resistor in series with a back gate node of the second bypass switch, the third and fourth bypass switch resistors self-bootstrapping the second bypass switch.
5. The circuit of claim 2 , wherein the FET switch is a pass-gate switch.
6. The circuit of claim 5 , wherein the pass-gate switch is selected from the group consisting of an NMOS transistor, a PMOS transistor, and an NMOS transistor in parallel with a PMOS transistor.
7. The circuit of claim 2 , wherein the FET switch is an RF switch.
8. The circuit of claim 7 , wherein the RF switch is selected from the group consisting of a transmit/receive switch, a switched attenuator, multipole/multithrow (MPMT) switches, and a capacitor band-switched VCO.
9. The circuit of claim 1 , wherein the switch comprises a plurality of cascaded transistors.
10. The circuit of claim 1 , wherein the switch is a MEMS switch.
11. A method of dynamically self-bootstrapping a switch comprising:
connecting a first resistor between a control node of the switch and a switch control input;
allowing a voltage on the control node to track an input signal voltage when the switch is in an on-state;
preventing the voltage on the control node from tracking the input signal voltage when the switch is in an off-state by bypassing the first resistor with a first bypass switch; and
self-bootstrapping the first bypass switch with a first bypass switch resistor in series with a gate node of the first bypass switch and a second bypass switch resistor in series with a back gate node of the first bypass switch.
12. The method of claim 11 , wherein the switch is a FET switch and the control node is a gate node of the FET switch.
13. The method of claim 12 , further comprising:
connecting a second resistor between a back gate node of the FET switch and ground; and
bypassing the second resistor with a second bypass switch when the FET switch is in an off-state.
14. The method of claim 13 , further comprising self-bootstrapping the second bypass switch with a third bypass switch resistor in series with a gate node of the second bypass switch and a fourth bypass switch resistor in series with a back gate node of the second bypass switch.
15. The method of claim 12 , wherein the FET switch is a pass-gate switch.
16. The method of claim 15 , wherein the pass-gate switch is selected from the group consisting of an NMOS transistor, a PMOS transistor, and an NMOS transistor in parallel with a PMOS transistor.
17. The method of claim 12 , wherein the FET switch is an RF switch.
18. The method of claim 17 , wherein the RF switch is selected from .the group consisting of a transmit/receive switch, a switched attenuator, multipole/multithrow (MPMT) switches, and a capacitor band-switched VCO.
19. The method of claim 11 , wherein the switch comprises a plurality of cascaded transistors.
20. The method of claim 11 , wherein the switch is a MEMS switch.