Circuits, devices and methods related to audio amplifiers having gain calibration

A method for calibrating an audio amplification system, the method comprising:

• injecting a tone having a frequency to an input path of an audio amplifier, such that an input signal provided to the audio amplifier includes the tone signal;
• sampling an output signal at an output node of the audio amplifier;
• sampling the input signal at an input node of the audio amplifier;
• and
• generating a correction signal based on the sampled output signal and the sampled input signal to correct for a gain variation of the audio amplifier.

An audio amplification system comprising:

• a digital audio path configured to provide a digital signal;
• an audio amplifier configured to receive the digital signal as an input signal and generate an output signal;
• and
• a calibration circuit including a tone generator configured to inject a tone having a frequency to the digital audio path, such that the input signal includes the tone, the calibration circuit further including a first sampling circuit configured to sample the output signal at an output node of the audio amplifier, and a second sampling circuit configured to sample the input signal at an input node of the audio amplifier, the calibration circuit further including a gain adjustment circuit configured to generate a correction signal based on the sampled output signal and the sampled input signal to correct for a gain variation of the audio amplifier.