FAST_SYNCHRONIZING

Published:2009/7/14 4:38:00 Author:May | From:SeekIC

Combination of phase splitter and DAC provides accurate synchronization of high-stability VCO with external reference frequency. IC divides reference frequency by 4 and provides two signals 90° apart, while IC2 divides VC0 frequency similarly by 4. Phase relationship between outputs of IC3 depends on whether VCO is higher or lower than reference, while frequency of IC3 outputs depends on difference between oscillator and reference frequencies, Schmitt triggers IC4 and IC5 supply clock and up/down control to counter IC6. If VC0 frequency is low, IC6 counts up at rate proportional to frequency difference and delivers increasing control voltage to VCO as required for increasing oscillator frequency.-H. W. Cooper, Oscillator Synchronizer Is Fast Acting, EDN Magazine, July 20, 1973, p 83-84.



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