| 摘要 |
In a demodulator circuit for processing a frequency-modulated (fm) signal, two rectangular-wave signals of opposite phase are generated from the fm signal and separately processed in two similar circuit paths. Each circuit path includes an inverter that receives one of the rectangular-wave signals and a NOR gate that receives both the rectangular-wave signal and its inverted version from the inverter. By imparting a slight delay on positive-going transitions of the inverted signal, a pulse stream is produced by the NOR gate in coincidence with such transitions. The pulse streams from both paths are combined to obtain a resultant signal having a pulse repetition rate that is twice the frequency of the fm carrier. Temperature-caused pulse variations in one circuit path relative to the other . . . which will allow the fundamental carrier frequecy to reappear . . . are stabilized by having the inverters, and the NOR gates, in thermally-coupled packages.
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