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 operating in one of a static mode and a dynamic mode, the power supply producing the supply voltage as a substantially constant voltage independent of an amplitude of the input signal when operating in a static mode and the power supply producing the supply voltage as a dynamically varying envelope tracking voltage tracking an amplitude of the input signal when operating in the dynamic mode;
• 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 power supply is operating in the static mode 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 power supply is operating in the dynamic mode;
• 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 time-aligning a supply voltage to a power amplifier in an envelope tracking power amplifier system, the method comprising:

• generating an envelope tracking signal tracking a detected amplitude of an input signal to the power amplifier;
• at a first time instance, operating the power supply in a static mode to produce the supply voltage as a substantially constant voltage independent of the envelope tracking signal;
• at a second time instance, operating the power supply in a dynamic mode to produce the supply voltage as a dynamically varying envelope tracking voltage based on the envelope tracking signal;
• determining a first delay between the input signal and an output signal of the power amplifier based on portions of the input signal and the output signal captured when the power supply is operating in the static mode;
• determining 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 power supply is operating in the dynamic mode;
• storing values for the first and second delay as calibration values;
• determining an initial delay mismatch between the input signal to the power amplifier and the supply voltage, the determined delay mismatch based on a difference between the first delay and the second delay;
• after configuring the delay block based on the calibration values, operating the power supply in the static mode;
• determining a third delay between the input signal and the output signal based on portions of the input signal and the output signal captured when the power supply is operating in the static mode;
• determining an adjusted delay mismatch based on a difference between the third delay and the first delay;
• configuring a delay block to compensate for the determined adjusted delay mismatch;
• and
• amplifying, by a power amplifier, the input signal to generate an output signal, the power amplifier powered from the supply voltage.