| 摘要 |
A frequency modulation signal demodulator receives an intermediate frequency signal to demodulate a FM signal. The frequency modulation signal demodulator includes a voltage-controlled oscillator having variable capacitance diodes, The voltage-controlled oscillator varies the oscillating frequency of a signal by controlling a voltage across the variable capacitance diodes using a DC voltage. Also included is a phase comparator which produces a phase difference by comparing the phase of the intermediate frequency signal to the phase of the signal from the voltage-controlled oscillator and provides a direct current voltage signal corresponding to the phase difference. Also included is a differential amplifier which has an adjustable reference voltage source. The differential amplifier amplifies the direct current voltage signal to produce a demodulated signal. The demodulated signal is negatively fedback to the voltage-controlled oscillator as the direct current signal. |
