Adaptive biasing in a power amplifier circuit

A wireless device comprising a wireless transmission circuit comprising:

• a power management integrated circuit (PMIC) configured to generate a modulated voltage based on a preestablished lookup table (LUT) that correlates a time-variant target voltage with the modulated voltage;
• and
• a power amplifier apparatus comprising:
• a current source configured to generate a low-frequency current;
• and
• a power amplifier circuit comprising:
• a bias circuit configured to generate a bias voltage based on the low-frequency current;
• and
• an output stage biased by the bias voltage to amplify a radio frequency (RF) signal based on the modulated voltage;
• and
• an adaptive bias circuit coupled to the bias circuit and configured to inject an adaptive bias current into the bias circuit to dynamically adjust one or more of an amplitude-amplitude (AM/AM) characteristic and an amplitude-phase (AM/PM) characteristic of the modulated voltage.

A method for enabling adaptive biasing in a power amplifier circuit comprising:

• generating a low-frequency current;
• generating a bias voltage based on the low-frequency current;
• using the bias voltage to bias an output stage in the power amplifier circuit to thereby amplify a radio frequency (RF) signal based on a modulated voltage;
• and
• injecting an adaptive bias current into the power amplifier circuit to dynamically adjust one or more of an amplitude-amplitude (AM/AM) characteristic and an amplitude-phase (AM/PM) characteristic of the modulated voltage.