How ALA circuit works

The working principle of this circuit is as follows: the output stage current waveform detection and the original input signal are input into a comparator
for comparison, and the voltage difference between the two is used as an independent distortion signal, which is inverted and then input into the current amplification stage. .
    The schematic diagram of its working principle is shown in Figure 1-390. It consists of a distortion detector and an adder circuit. The distortion detector
detects the distortion of the amplifier in real time and filters out the fundamental wave. It is sent to the inverting input end of the adder A3 and added to the original signal of the amplifier .
The sum is used as the coefficient K o. Assume that the final stage The gain is l, and the distortion of the original power amplifier is D, then the distortion D after the ALA circuit
is:
    D'=(1-K)D
. Obviously, when K =1, D'=O means zero distortion.