ANALOG_PLL_AS_FM_DEMODULATOR

Published:2009/7/4 19:42:00 Author:May | From:SeekIC

Upper frequency limit of about 50 MHz for NE562 and other monolithic analog phase-locked loops complicates construction of FM telemetry receivers that directly demodulate standard 88-108 MHz FM broadcast signals. Circuit shown solves problem, with only small amount of signal preconditioning, by first converting RF carrierto 10.7 MHz with conventional superheterodyne front end, then applying signal to phase detector of PLL with VCO set to run free at 10.7 MHz. Input sensitivity is less than 30 μV, and audio output is greater than 100 mV.-E. Murthi, Monolithic Phase-Locked Loops-Analogs Do All the Work of Digitals, and Much More, EDN Magazine, Sept. 5, 1977, p 59-64.



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