Power amplifier circuitry and method
View Patent ↗A method and apparatus is provided for use in power amplifiers for reducing the peak voltage that transistors are subjected to. A power amplifier is provided with first and second switching devices and an inductor connected between the switching devices. The switching devices are driven such that the switching devices are turned on and off during the same time intervals.
1. A method of providing a complementary metal oxide semiconductor (CMOS) RF power amplifier for a wireless transmission system comprising:
forming RF power amplifier input stage circuitry using devices with a first gate oxide thickness;
forming RF power amplifier output stage circuitry, the output stage circuitry having p-channel devices (PMOS), n-channel devices (NMOS), and an inductive network;
forming the PMOS devices using devices with the first gate oxide thickness;
forming the NMOS devices using devices with a second gate oxide thickness, wherein the first gate oxide thickness is less than the second gate oxide thickness; and
selecting values of inductors in the inductive network and input capacitances of at least some of the devices in the output stage circuitry to distribute voltage swings across the NMOS and PMOS devices in such way that the NMOS devices are subjected to greater voltage swings than the PMOS devices.
2. The method of claim 1 , wherein the first gate oxide thickness is approximately 70 Angstroms.
3. The method of claim 1 , wherein the second gate oxide thickness is approximately 140 Angstroms.
4. The method of claim 1 , further comprising using one or more inverters in the input stage circuitry.
5. The method of claim 4 , wherein the PMOS devices and NMOS devices are switching devices.
6. A complementary metal oxide semiconductor (CMOS) RF power amplifier for a wireless transmission system comprising:
RF power amplifier input stage circuitry including switching devices having a first gate oxide thickness;
RF power amplifier output stage circuitry having a plurality of switching devices and an inductive network;
wherein the plurality of switching devices of the output stage circuitry includes p-channel devices (PMOS) having the first gate oxide thickness and n-channel devices (NMOS) having a second gate oxide thickness, and wherein the first gate oxide thickness is less than the second gate oxide thickness; and
wherein the values of inductors in the inductive network and input capacitances of at least some of the switching devices in the output stage circuitry are selected to distribute voltage swings across the NMOS and PMOS devices in such way that the NMOS devices are subjected to greater voltage swings than the PMOS devices.
7. The RF power amplifier of claim 6 , wherein the first gate oxide thickness is approximately 70 Angstroms.
8. The RF power amplifier of claim 6 , wherein the second gate oxide thickness is approximately 140 Angstroms.
9. The RF power amplifier of claim 6 , wherein the input stage circuitry further comprises one or more inverters.
10. A method of providing an RF power amplifier for a wireless transmission system comprising:
forming an RF power amplifier input stage using switching devices having a first gate oxide thickness;
forming an RF power amplifier output stage using p-channel devices (PMOS), n-channel devices (NMOS), and a plurality of inductors;
forming the PMOS devices using devices with the first gate oxide thickness; and
forming the NMOS devices using devices with a second gate oxide thickness, wherein the first gate oxide thickness is less than the second gate oxide thickness.
11. The method of claim 10 , wherein the output stage includes a plurality of inductors, the method further comprising distributing voltage swings across the NMOS and PMOS devices by selecting values of the inductors and input capacitances of at least some of the devices in the output stage,. wherein the voltage swings are distributed in such way that the NMOS devices are subjected to greater voltage swings than the PMOS devices.
12. The method of 10 , wherein the first gate oxide thickness is approximately 70 Angstroms.
13. The method of claim 10 , wherein the gate oxide thickness is approximately 140 Angstroms.
14. The method of claim 10 , further comprising using one or more inverters in the input stage.
15. The method of claim 12 , wherein the PMOS devices and NMOS devices are switching devices.