JPS5720032A - Phase synchronizing circuit of counting circuit - Google Patents

Abstract

PURPOSE:To apply a circuit to the counting of a clock signal over a wide frequency range by finding a phase error between outputs of counting circuits and by resetting each counting circuit on the basis of the phase error output. CONSTITUTION:As phase synchronizing circuits, exclusive OR circuits 14 and 15 are provided corresponding to subordinate counting circuits 12 and 13. The output of a main counting circuit 11 and those of the circuits 12 and 13 are logically processed by the circuits 14 and 15 and when their outputs are 1s, the circuits 12 and 13 are reset. Therefore, only when the count output of the circuit 11 is out of phase with that of the circuit 12 or 13, the circuit 12 or 13 is cleared to return its count output to a 0. At the point in time when the count is returned to the 0, the outputs of the circuits 14 and 15 become 0s, so the circuits 12 and 13 are enabled to count again. In this state, the acquisition of phase synchronism of the circuits 12 and 13 is completed.