Gremblnote Application Note GN-0001: OTA-based Automatic Gain Control (AGC) Circuit

Schematic diagram for Automatic Gain Control (AGC) circuit)

I developed this automatic gain control (AGC) circuit to compensate for the -3 dB gain after each filter stage in a 2-stage, 4-pole voltage-controlled filter (VCF). I’m posting this because it was surprisingly difficult (rather, impossible) to find a low-distortion operational transconductance amplifier (OTA) driven AGC schematic I could use directly.