Switching circuit

1. A switching circuit comprising:

a passive switch coupled to a first switch terminal;

a driving switch coupled in series with the passive switch and a second switch terminal, the driving switch configured to turn the passive switch on and off;

a power source configured to provide power to the passive switch and the driving switch; and

a monitoring circuit configured to:

receive an indication that a switching circuit voltage exceeds a predetermined amount and, in response, reduce the power provided to the driving switch; or

receive an indication that a switching circuit current exceeds a predetermined amount and, in response, reduce the power provided to the driving switch.

2. The switching circuit of claim 1 wherein the switching circuit current is a current passing from the first switch terminal to the second switch terminal.

3. The switching circuit of claim 1 wherein the switching circuit voltage is a voltage at a first switch terminal.

4. The switching circuit of claim 1 wherein the driving switch comprises a MOSFET.

5. The switching circuit of claim 1 wherein the passive switch comprises a plurality of switches connected in series.

6. The switching circuit of claim 1 wherein the passive switch comprises a first JFET and a second JFET connected in series.

7. The switching circuit of claim 1 wherein the passive switch comprises a first MOSFET and a second MOSFET connected in series.

8. The switching circuit of claim 1 wherein an intermediary switch coupled to the passive switch enables the passive switch to switch simultaneously with the driving switch.

9. The switching circuit of claim 8 wherein the intermediary switch comprises a gate, a drain, and a source, the gate operably coupled to the power source, and the drain operably coupled to the passive switch.

10. The switching circuit of claim 1 wherein the monitoring circuit is configured to:

receive an indication that a switching circuit voltage exceeds a predetermined amount and, in response, reduce the power provided to the driving switch; and

receive an indication that a switching circuit current exceeds a predetermined amount and, in response, reduce the power provided to the driving switch.

11. The switching circuit of claim 10 wherein:

the indication that the switching circuit voltage has exceeded a predetermined amount is received by a first comparator; and

the indication that the switching circuit current has exceeded a predetermined amount is received by a second comparator.

12. The switching circuit of claim 10 wherein:

the indication that the switching circuit voltage has exceeded a predetermined amount is provided by a voltage sensing circuit, the voltage sensing circuit comprising (a) a first transformer operably coupled to the second terminal and (b) a first diode operably coupled to the monitoring circuit; and

the indication that the switching circuit current has exceeded a predetermined amount is provided by a current sensing circuit, the current sensing circuit comprising (a) a second transformer operably coupled to the second terminal and (b) a second diode operably coupled to the monitoring circuit.

13. The switching circuit of claim 1 wherein the power source comprises a switched mode power supply.

14. The switching circuit of claim 13 further comprising a gate driver operably coupled to the switched mode power supply, a gate of the passive switch, and a gate of the driving switch.

15. An RF impedance matching network comprising:

an RF input configured to couple to an RF source, the RF source having a fixed RF source impedance;

an RF output configured to couple to a load, the load having a variable load impedance;

a first circuit comprising a first variable component providing a first variable capacitance or inductance; and

a second circuit comprising a second variable component providing a second variable capacitance or inductance;

wherein each of the first circuit and the second circuit comprise a plurality of switching circuits configured to provide the first variable capacitance or inductance and the second variable capacitance or inductance, respectively, each of the plurality of switching circuits comprising:

a passive switch coupled to a first switch terminal;

a driving switch coupled in series with the passive switch and a second switch terminal, the driving switch configured to turn the passive switch on and off; and

a power source configured to provide power to the passive switch and the driving switch.

16. The RF impedance matching network of claim 15 further comprising a monitoring circuit configured to:

receive an indication that a switching circuit voltage exceeds a predetermined amount and, in response, reduce the power provided to the driving switch; or

receive an indication that a switching circuit current exceeds a predetermined amount and, in response, reduce the power provided to the driving switch.

17. A method of controlling a switching circuit, the method comprising:

providing a switching circuit comprising:

a passive switch coupled to a first switch terminal;

a driving switch coupled in series with the passive switch and a second switch terminal, the driving switch configured to turn the passive switch on and off;

a power source configured to provide power to the passive switch and the driving switch; and

a monitoring circuit;

receiving at the monitoring circuit (a) an indication that a switching circuit voltage exceeds a predetermined amount or (b) an indication that a switching circuit current exceeds a predetermined amount; and

reducing the power provided to the driving switch in response to the receipt of indication (a) or (b), the reduction of power switching off the switching circuit.

18. The method of claim 15 wherein the monitoring circuit is configured to:

receive an indication that a switching circuit voltage exceeds a predetermined amount and, in response, reduce the power provided to the driving switch; and

receive an indication that a switching circuit current exceeds a predetermined amount and, in response, reduce the power provided to the driving switch.

19. The method of claim 17 wherein an intermediary switch coupled to the passive switch enables the passive switch to switch simultaneously with the driving switch.

20. The method of claim 19 wherein the intermediary switch comprises a gate, a drain, and a source, the gate operably coupled to the power source, and the drain operably coupled to the passive switch.