PHASE SYNCHRONIZING METHOD, PHASE SYNCHRONIZING CIRCUIT, SYSTEM FOR DETECTING DATA SPEED AND SELF-ADVANCING OSCILLATING PERIOD CONTROL MEANS FOR PHASE SYNCHRONIZING CIRCUIT

摘要

PURPOSE:To surely execute phase synchronization in a shot time even when data to be widely different in data speeds mixedly exist by phase-synchronizing the output of an oscillating circuit controlled in a self-advancing oscillating period specified with the data speed of read data beforehand to a reference signal synchronizing with the read data at the arbitrary data speed. CONSTITUTION:An oscillation permitting signal 13 is generated by the rise of read data 12, and the oscillation is started in a voltage controlled oscillator 5 by the signal. When the portion of one pulse of a reference signal 15 is outputted by such an output 14, the signal 13 is made oscillation-inpermissible by the fall of the pulse, and the oscillator 5 is stopped. Since oscillators 5 and 1 are oscillated by the self-advancing oscillations in the period equal to the ideal oscillating period specified with a data transfer speed according to a control signal 17 beforehand, a reference signal pulse width is equal to a clock signal pulse width T specified from the read data, and it is made equal to the self-advancing oscillating period of the oscillator 10. Thereafter, the phase difference between the reference signal 15 and an oscillating clock signal 22 is detected by a comparator 7, and the advance and lag of the phase are controlled according to it.