Sensitive frequency demodulator LM565 LM111

As shown for the sensitive frequency demodulation circuit. The circuit uses IC LM565 phase-locked configuration, can track the frequency offset over a wide frequency range. How
Sensitive frequency demodulator LM565 LM111 - schematic

ever, at small offsets the signal, due to the small demodulated output signal, the voltage controlled oscillator will drift a drift of the operating point of the comparator generates an error. This circuit is to overcome the above drawbacks, the circuit plus a DC regeneration section, which can stably work for a small deviation signal. FIG, the demodulation circuit and general frequency demodulation circuit LM565 and LM111 comparator constituted substantially the same. The difference is that this circuit A2 pin input signal is not removed from the LM565 feet, but was removed from the peak hold circuit A1. During the interval of the FM input signal, the output of A1 is low, thus holding the capacitor C1 is discharged A1 low output impedance, and the peak hold signal. With this direct approach to regeneration, despite the presence of a voltage controlled oscillator drift, but the peak hold circuit output can be tracked, so that the comparator can work.

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