Abstract: A reduced-complexity automatic frequency control (AFC) loop to match the frequency of a receiver to that of a transmitter. A received input signal is multiplied with the sine and cosine signals of a voltage-controlled-oscillator, digitized and filtered, and the sign (the most significant bit) of the cosine function of the received input signal is sliced off by a sign slicer circuit to provide an input to two sign gates. The outputs of the two sign gates are added to produce an estimate of the frequency error, which is used to control the voltage-controlled-oscillator to match the received signal's frequency. The required number of multiplier circuits required to implement the AFC loop is reduced from prior art AFC loops by the use of the sign slicer circuit and the use of the sign gates.