| 摘要 |
An FM receiver comprises a complex detector for complex detecting an FM signal by using, as a reference signal, a local oscillator signal having a frequency substantially equal to the carrier frequency of the FM signal; a first low-pass filter for filtering out the real part of the complex output signal from the complex detector; a second low-pass filter for filtering out the imaginary part of the complex signal; a complex voltage-controlled oscillator operating in the positive and negative frequency ranges including the zero frequency and being frequency controllable with a frequency control signal; an operational circuit for taking out one of the imagery and the real part signals of the product of the output complex conlugate signal from the complex voltage-contolled oscillator and the filtered complex signals from the first and second low-pass filters; and a third low-pass filter for filtering the output of the operational circuit to provide a demodulated output and to feed the same back as the frequency control signal to the complex voltage-controlled oscillator. |
