APPARATUS AND METHODS FOR CALIBRATING ENVELOPE TRACKERS

Apparatus and methods for envelope tracking calibration are provided. In one embodiment, a power amplifier system includes a power amplifier, an envelope tracker that generates the power amplifier's supply voltage, a power detector, and a calibration module. The envelope tracker includes an envelope shaping table generated at a desired gain compression and a scaling module that scales an amplitude of an envelope signal. The power detector measures the power amplifier's output power, and the calibration module provides calibration data to the scaling module to change the scaling of the envelope signal's amplitude. The calibration module sets the calibration data to a first value corresponding to a supply voltage level associated with substantially no gain compression, and reduces the supply voltage level by changing the calibration data until the power detector indicates that the gain compression of the power amplifier is about equal to the desired gain compression.