Adjustable gate and/or body resistance for improved intermodulation distortion performance of radio-frequency switch
Radio-frequency (RF) switch circuits are disclosed having adjustable resistance to provide improved switching performance. RF switch circuits include at least one field-effect transistor (FET) disposed between first and second nodes, each of the FET having a respective gate and body. An adjustable-resistance circuit is connected to either or both of the respective gate and body of the FET(s).
1. A radio-frequency (RF) switch comprising:
at least one field-effect transistor (FET) disposed between first and second nodes, each of the FET having a respective gate and body; and
an adjustable-resistance circuit connected to either or both of the respective gate and body of the at least one FET, the adjustable-resistance circuit including a first resistor in series with a parallel combination of a second resistor and a bybass switch.
2. The RF switch of claim 1 wherein the FET is a silicon-on-insulator (SOI) FET.
3. The RF switch of claim 1 wherein the bypass switch being closed results in the second resistor being bypassed to yield a first resistance for the adjustable-resistance, and the bypass switch being open results in a second resistance that is greater than the first resistance by approximately the value of the second resistor.
4. The RF switch of claim 3 wherein the first resistance includes a bias resistance.
5. The RF switch of claim 4 wherein the second resistance is selected to improve intermodulation distortion (IMD) performance, and the first resistance is selected to yield a reduced impact on switching time of the FET.
6. The RF switch of claim 1 wherein the adjustable-resistance circuit is connected to the gate.
7. The RF switch of claim 6 further comprising a second adjustable-resistance circuit connected to the body.
8. The RF switch of claim 6 further comprising a diode body contact connected to the body.
9. The RF switch of claim 1 wherein the adjustable-resistance circuit is connected to the body but not the gate.
10. The RF switch of claim 1 wherein the first node is configured to receive an RF signal having a power value and the second node is configured to output the RF signal when the FET is in an ON state.
11. The RF switch of claim 10 wherein the at least one FET includes N FETs connected in series, the quantity N selected to allow the switch circuit to handle the power of the RF signal.
12. A method for operating a radio-frequency (RF) switch, the method comprising:
controlling at least one field-effect transistor (FET) disposed between first and second nodes so that each of the at least one FET is in an ON state or an OFF state; and
adjusting a resistance of a circuit connected to either or both of a respective gate and body of each of the at least one FET, the resistance including a first and a second resistors and the adjusting including bypassing one of the first and the second resistors that are connected in series.
13. A radio-frequency (RF) switch module comprising:
a packaging substrate configured to receive a plurality of components;
a semiconductor die mounted on the packaging substrate, the die including at least one field-effect transistor (FET); and
an adjustable-resistance circuit connected to either or both of a respective gate and body of each of the at least one FET, the adjustable-resistance circuit including a first resistor in series with a parallel combination of a second resistor and a bypass switch.
14. The switch module of claim 13 wherein the semiconductor die is a silicon-on-insulator (SOI) die.
15. The switch module of claim 13 wherein the adjustable-resistance circuit is part of the same semiconductor die as the at least one FET.
16. The switch module of claim 13 wherein the adjustable-resistance circuit is part of a second die mounted on the packaging substrate.
17. The switch module of claim 13 wherein the adjustable-resistance circuit is disposed at a location outside of the semiconductor die.