Method and apparatus for a power supply modulator linearizer
A method and apparatus for a power amplifier module is described. The module includes a power amplifier and a power supply modulator coupled to the power amplifier. In addition, the module includes an inverter coupled between the power amplifier and the power supply modulator. The inverter provides a predistorted signal to the power amplifier to cancel distortion in the power amplifier provided by the power supply modulator. In addition, the module can include a driver coupled between the power amplifier and the inverter wherein the driver supplies the predistorted signal to the power amplifier.
1. An apparatus comprising:
a power amplifier;
a power supply modulator coupled to the power amplifier, and
an inverter coupled between the power amplifier and the power supply modulator wherein the inverter provides a predistorted signal wherein the predistorted signal includes an inverted power supply signal and wherein the predistorted signal is provided to the power amplifier to cancel distortion in the power amplifier caused by the power supply modulator.
2. The apparatus of claim 1 further comprising a driver coupled between the power amplifier and the inverter wherein the driver supplies the predistorted signal to the power amplifier by the inverter providing an inverse modulated supply to the driver.
3. The apparatus of claim 2 comprising a radio frequency signal provided to the driver as an input signal to the apparatus.
4. The apparatus of claim 1 wherein the power supply modulator provides a modulated supply to the power amplifier and the inverter.
5. The apparatus of claim 4 wherein an envelope signal is input into the power supply modulator so that the power supply modulator provides the modulated supply to the power amplifier and the inverter.
6. The apparatus of claim 1 wherein the predistorted signal cancels phase and gain variations caused by the modulated supply to the power amplifier.
7. The apparatus of claim 1 wherein the power amplifier and the inverter are supplied on an integrated circuit.
8. The apparatus of claim 7 wherein a driver is supplied on the integrated circuit.
9. The apparatus of claim 7 wherein the integrated circuit is a lateral diffused MOSFET (LDMOS) integrated circuit.
10. A method comprising:
providing a radio frequency signal to a power amplifier;
providing a modulated supply to power amplifier
inverting the modulated supply to provide a predistorted signal wherein the predistorted signal includes an inverted power supply signal, and
providing the predistorted signal to the power amplifier to cancel distortion in the power amplifier caused by the power supply modulator.
11. The method of claim 10 wherein the radio frequency signal and the inverted modulated supply is supplied to a driver so that the driver supplies the predistorted signal to the power amplifier.
12. The method of claim 10 wherein providing a modulated supply comprises supplying a signal envelope to a power supply modulator.
13. The method of claim 12 wherein the power supply modulator is supplying the modulated supply to the power amplifier and an inverter.
14. The method of claim 10 further comprising canceling phase and gain variations caused by the modulated supply signal to the power amplifier.
15. The method of claim 10 further comprising providing the power amplifier and an inverter are supplied on an integrated circuit.
16. The method of claim 15 further comprising providing a driver on the integrated circuit.
17. The method of claim 15 wherein the integrated circuit is a lateral diffused MOSFET (LDMOS) IC.