An automatic gain control (AGC) circuit is included with the ADC and can be used to maintain nominally constant output signal amplitude when recording speech signals (it can be fully disabled if not desired). This circuitry automatically adjusts the PGA gain as the input signal becomes overly loud or very weak, such as when a person speaking into a microphone moves closer or farther from the microphone. The AGC algorithm has several programmable settings, including target gain, attack and decay time constants, noise threshold, and maximum PGA gain applicable that allow the algorithm to be fine tuned for any particular application. The algorithm uses the absolute average of the signal (which is the average of the absolute value of the signal) as a measure of the nominal amplitude of the output signal.

Note that completely independent AGC circuitry is included with each ADC channel with entirely independent control over the algorithm from one channel to the next. This is attractive in cases where two microphones are used in a system, but may have different placement in the end equipment and require different dynamic performance for optimal system operation.