Frequency demodulation circuit.

摘要

A frequency demodulation circuit having an improved detection sensitivity is provided by forming an all-pass equalizer in a Quadrature-type demodulator capable of allowing a band covering at least a carrier frequency deviation to pass therethrough. The equalizer comprises a band-pass filter for detecting the frequency deviation of an inputted FM carrier signal, a gain-doubling amplifier and a substractor for performing subtraction between the signal inputted to the band-pass filter and the output of the amplifier. The operation of the circuit is such that a FM carrier signal is supplied to the band-pass filter through a phase shifter and to a phase comparator and the output of the substractor and the FM carrier signal are compared to each other by the phase comparator to thereby obtain a FM demodulated signal. <IMAGE>