Envelope Tracking Power Amplifier System with Delay Calibration

A power amplifier system comprising:

• a power amplifier amplifying an input signal to generate an output signal, the power amplify powered from a supply voltage;
• a power supply generating the supply voltage, the power supply producing the supply voltage as a substantially constant voltage when the input voltage is a below an amplitude threshold and the power supply producing the supply voltage as a dynamically varying envelope tracking voltage tracking an amplitude of the input signal when the input voltage is above the amplitude threshold;
• a delay determiner to determine a first delay between the input signal and the output signal based on portions of the input signal and the output signal captured when the input signal is below the amplitude threshold, and to determine a second delay between the input signal and the output signal based on portions of the input signal and the output signal captured when the input signal is above the amplitude threshold;
• and
• a delay block programmable by the delay determiner, the delay block to compensate for a determined delay mismatch between the input signal to the power amplifier and the supply voltage, the determined delay based on a difference between the first delay and the second delay.

A method for delay calibration in an envelope tracking power amplifier system having a signal path and an envelope tracking path, the method comprising:

• generating, by the envelope tracking path, a supply voltage to a power amplifier based on a detected amplitude of the input signal;
• amplifying, by a power amplifier in the signal path, the input signal to generate an output signal, the power amplifier powered from the supply voltage;
• monitoring an operating condition of the envelope tracking power amplifier system;
• performing a lookup of the operating condition in a lookup table to map the operating condition to an expected delay mismatch between a signal path and an envelope tracking path;
• configuring a delay block in at least one of the signal path and the envelope tracking path to compensate for the expected delay mismatch between the signal path and the envelope tracking path.