Superheterodyne circuit is a circuit in which the incoming signal in a first detector (or mixer) beats with the signal of a local oscillator, resulting in a lower (intermediate) frequency, which then is amplified by an intermediate-frequency (IF) amplifier. This IF signal is detected by a second detector whose output is amplified by an audio frequency (AF) amplifier. Because the IF amplifier operates at a single (fixed) frequency, it can be adjusted for optimum selectivity and gain. Also called superhet circuit.
See also, Superheterodyne receiver