CLOCK GENERATING CIRCUIT FOR EXTRACTING DIGITAL DATA

摘要

PURPOSE:To attain optimum clock extraction by selecting the relation of phase between an input digital data and a clock as pi/2. CONSTITUTION:A pulse with a prescribed width generated from the ries of an input digital data and a signal being 1/2 frequency division of an output of a VCO 11 are inputted to a 2nd comparator circuit 10 and synchronization is applied at a point of pi/2 for the data being an optimum extraction point. Thus, the phase synchronization of pi/2 is applied between a pulse generated at the rising/falling of the input digital data and the clock being an output of the VCO 11. Then an error voltage outputted from a 2nd comparator circuit 17 is fed to a control voltage for setting pulse width of a 1st monostable multivibrator 10 so as to bring the phase difference to be pi/2. Thus, the data and clock are synchronized by the relation of phase of pi/2 without fail to attain the optimum clock extraction.