Apparatus and methods for delay calibration of load modulated power amplifiers and envelope trackers

Abstract

Apparatus and methods for delay calibration of load modulated power amplifiers and envelope trackers are disclosed herein. In certain embodiments, a load modulated power amplifier system includes a power amplifier that receives a radio frequency (RF) signal at an input, a controllable load impedance coupled to an output of the power amplifier and having an impedance modulated by an envelope control signal, and a calibration circuit that selects a time delay for aligning the envelope control signal to the RF signal. The time delay is selected based at least partly on an error vector magnitude (EVM) detected at the output of the power amplifier.

Dependencies are inferred from the claim text.