RF switch having independently generated gate and body voltages
In some method and apparatus embodiments, an RF circuit comprises a switch transistor having a source, a drain, a gate, and a body. A gate control voltage is applied to the gate of the switch transistor. A body control voltage is applied to the body of the switch transistor. The body control voltage is a positive bias voltage when the switch transistor is in an on state. In some embodiments, an RF circuit comprises a control voltage applied to the gate of the switch transistor through a first resistance and applied to the body of the switch transistor through a second resistance. The first resistance is different from the second resistance.
1. A Radio Frequency (RF) switch core comprising:
a first RF switch coupled in series between an upstream RF node and a downstream RF node, wherein the first RF switch comprises a first series connected plurality of transistors, further wherein each of the transistors of the first series connected plurality of transistors is configured to receive a first gate control voltage and a first body control voltage, further wherein the first body control voltage is produced independently of the first gate control voltage and is a positive bias equal to or greater than the first gate control voltage during an ON state of the first RF switch; and
a second RF switch coupling the downstream RF node to ground.
2. The RF switch core of claim 1 , wherein the second RF switch comprises a second series connected plurality of transistors, further wherein each of the transistors of the second series connected plurality of transistors is configured to receive a second gate control voltage and a second body control voltage, further wherein the second body control voltage is positively biased during an ON state of the second RF switch.
3. The RF switch core of claim 1 , further comprising:
a first voltage control source configured to produce the first gate control voltage; and
a second voltage control source configured to produce the first body control voltage, wherein the second voltage control source is different from the first voltage control source.
4. The RF switch core of claim 1 , wherein:
a first level shifter configured to produce the first gate control voltage; and
a second level shifter configured to produce the first body control voltage.
5. The RF switch core of claim 1 , further comprising:
a decoder configured to decode control signals and to provide decoded signals to a first voltage control source associated with the first body control voltage.
6. The RF switch core of claim 1 , wherein the first RF switch comprises:
a first N-channel transistor having a source coupled to a drain of a second N-channel transistor.
7. The RF switch core of claim 1 , further wherein the first body control voltage is greater than a built-in p-n junction diode of a transistor of the first RF switch during the ON state of the first RF switch.
8. The RF switch core of claim 1 , wherein the second RF switch comprises:
a first N-channel transistor having a drain coupled to the downstream RF node and a source coupled to a drain of a second N-channel transistor.
9. The RF switch core of claim 1 , wherein the first body control voltage is greater than 0.7V during the ON state of the first RF switch.
10. A Radio Frequency (RF) circuit comprising:
a first RF switch coupling an RF downstream node to ground, wherein the first RF switch comprises a first series connected plurality of transistors, further wherein each transistor of the first series connected plurality of transistors is configured to receive a first gate control voltage produced by a first voltage source and a first body control voltage produced by a second voltage source, further wherein the first body control voltage is a positive bias equal to or greater than the first gate control voltage during an ON state of the first RF switch; and
a second RF switch coupled in series between an RF antenna side node and the RF downstream node.
11. The RF circuit of claim 10 , wherein the second RF switch comprises a second series connected plurality of transistors, further wherein each transistor of the second series connected plurality of transistors is configured to receive a second gate control voltage and a second body control voltage, further wherein the second body control voltage is positively biased during an ON state of the second RF switch.
12. The RF circuit of claim 10 , further comprising:
a decoder configured to decode control signals and to provide decoded signals to the first voltage source.
13. The RF circuit of claim 10 , wherein the first RF switch comprises:
a first N-channel transistor having a source coupled to a drain of a second N-channel transistor.
14. The RF circuit of claim 10 , wherein the first voltage source comprises a level shifter.
15. A Radio Frequency (RF) circuit for routing an RF carrier signal between an antenna and downstream components of an RF device, the RF circuit comprising:
a first RF switch coupled between the antenna and a downstream node, wherein the first RF switch comprises a first plurality of N-channel transistors connected in series, further wherein each N-channel transistor of the first plurality of N-channel transistors is configured to receive a first gate control voltage produced by a first voltage source and a first body control voltage produced by a second voltage source, further wherein the first body control voltage is a first positive bias equal to or greater than the first gate control voltage during an ON state of the first RF switch; and
a second RF switch coupled between the downstream node and ground, wherein the second RF switch comprises a second plurality of N-channel transistors connected in series, further wherein each N-channel transistor of the second plurality of N-channel transistors is configured to receive a second gate control voltage produced by the first voltage source and a second body control voltage produced by the second voltage source, further wherein the second body control voltage is a second positive bias during an ON state of the second RF switch.
16. The RF circuit of claim 15 , wherein the first voltage source comprises:
a positive voltage generator;
a negative voltage generator; and
a voltage level shifter configured to operate under control of the positive voltage generator and the negative voltage generator.
17. The RF circuit of claim 15 , further wherein the first body control voltage is greater than a built-in p-n junction diode of a transistor of the first RF switch during the ON state of the first RF switch.
18. The RF circuit of claim 15 , further comprising:
a decoder configured to decode control signals and to provide decoded signals to the first voltage source.
19. The RF circuit of claim 15 , wherein the first RF switch comprises:
a first N-channel transistor having a source coupled to a drain of a second N-channel transistor.
20. The RF circuit of claim 15 , wherein the first body control voltage is greater than 0.7V during the ON state of the first RF switch.