Patent ID: 9680434
Date: 2017-06-13
CPC Classifications: H03F,H03G

Claim:
1. A method of envelope tracking calibration for a supply voltage to a power amplifier within a radio frequency transmitter, comprising: applying an envelope signal that varies with time to an input of the radio frequency transmitter; determining when an instantaneous output power signal for the power amplifier is close to a power amplifier saturation power; mapping a gain of the power amplifier to an instantaneous output of a waveform signal amplified by the power amplifier; adaptively adjusting a gain compression of the power amplifier by using values stored in an amplitude modulation-to-amplitude modulation (AM-AM) table and an amplitude modulation-to-phase modulation (AM-PM) table of a digital predistorter, wherein the gain is compressed less when the instantaneous output power signal is close to the power amplifier saturation power and compressed more when the instantaneous output power signal is several dB smaller than the power amplifier saturation power; applying a supply voltage to the power amplifier based on the mapping and the power amplifier compression; and performing envelope tracking calibration based upon the input envelope supply voltage signal and the instantaneous output power signal.