Patent ID: 9094067
Filing Date: 2015-07-28
Classification: H03F,H04B

Abstract:
1. A method of calibrating an envelope tracking system for a supply voltage for a power amplifier module within a radio frequency (RF) transmitter module of a wireless communication unit; the method comprising, within at least one signal processing module of the wireless communication unit: applying a training signal comprising an envelope that varies with time to an input of the RF transmitter module; receiving at least an indication of at least one instantaneous output signal value for the power amplifier module in response to the training signal; and adjusting a timing alignment between an envelope tracking path of the envelope tracking system and a transmit path of the RF transmitter module to align an envelope tracking power amplifier module supply voltage to at least one instantaneous envelope of a waveform signal to be amplified by the power amplifier module, based at least partly on a gain symmetry corresponding to a first gain of the power amplifier module at a first time point and a second gain of the power amplifier module at a second time point or a phase symmetry corresponding to a first phase of a power amplifier output signal at a first time point and a second phase of a power amplifier output signal at a second time point calculated by referring to at least partly the received at least an indication of the at least one instantaneous output signal value for the power amplifier module in response to the training signal.