Lookup table calibration apparatus and method

A lookup table calibration apparatus comprising:

• a power amplifier circuit comprising:
• a phase shifter circuit configured to phase-shift a radio frequency (RF) signal based on a modulated phase correction voltage generated based on a phase correction voltage lookup table comprising a plurality of power indexes each correlating a respective power level of the RF signal with a respective one of a plurality of phase correction voltage targets;
• and
• a power amplifier configured to amplify the phase-shifted RF signal based on a modulated voltage generated based on a modulated voltage lookup table comprising the plurality of power indexes each correlating the respective power level of the RF signal with a respective one of a plurality of modulated voltage targets;
• and
• a calibration control circuit configured to, for each of the plurality of power indexes:
• adjust the modulated voltage until a measured gain of the amplified RF signal equals a reference gain;
• update the respective one of the plurality of modulated voltage targets in the modulated voltage lookup table based on the adjusted modulated voltage;
• adjust the modulated phase correction voltage until a measured phase of the amplified RF signal equals a reference phase;
• and
• update the respective one of the plurality of phase correction voltage targets in the phase correction voltage lookup table based on the adjusted modulated phase correction voltage.