Integrated FM detector including an oscillator having a capacitor and Schmitt trigger

摘要

An FM detector for demodulating frequency modulated signals includes an FM detector having an oscillator composed of a capacitor and a Schmitt Trigger. The oscillator is controlled by the input signal to the FM detector. The FM detector also includes a phase detector for mixing the input signal with an oscillator signal from the oscillator to provide an output signal. The frequency of the oscillator is set to the frequency of the input signal using components internal to the FM detector. A first switch is used to charge and discharge the capacitor in accordance with the state of the Schmitt Trigger. A second switch is used to set the frequency of the oscillator to the frequency of the input signal.