Bus aligned quadrature FM detektor

摘要

In a quadrature FM detector, demodulation is performed by a product detector (18) which multiplies an amplitude limited FM modulated information signal by a version of the amplitude limited FM modulated information signal which has been phase shifted by a phase shifting network (26) including a single tuned LC circuit (32, 34). In order to assure that the LC circuit is tuned to the carrier frequency of the FM signal, the LC circuit is tuned by a variable impedance device (40) in response to a control signal generated by a bus controlled DAC (44). The control signal is coupled to the variable impedance device (40) at the same pin (42) of an integrated circuit (10) where the LC circuit is coupled to the demodulator. <IMAGE>