Demodulator, in particular of SECAM chrominance signal, with double frequency tuning

摘要

The circuit uses a small memory capacitor enabling integration within circuit. The demodulator for a chrominance signal comprises a controlled frequency oscillator (110) and a device (142) for adjusting the frequency of the oscillator as a function of the charging voltage of a memory capacitor (148). The adjusting device comprises a fine adjustment channel (152) for providing a first adjustment value as a function of the charging voltage of the memory capacitor, and a coarse adjusting channel (162) providing a second adjustment value. This second adjustment value is modified when the charging voltage of the memory capacitor (148) does not lie within a given range.