Augmented Feedback Error Correction (AFEC)

Here is an error correction technique that can be applied to class A and AB amplifiers to provide distortion reduction of up to 20 dB at 20 kHz.  This approach measures the difference between the input (the reference) and the main amplifier output   which also includes the error signal. The output of the measuring amplifier represents the error difference and is applied to the main  amplifier  feedback node as an error correction signal.   AFEC V1.0.pdf