Clock resynchronization circuit and method

Abstract

A control circuit receives a first clock signal at a first frequency, a frequency division signal specifying a divisor number, and a second clock signal at a second frequency (higher than the first frequency). The control circuit includes a phase control block that defines non-overlapping portions of a pulse of the second clock to include center, left and right portions. A determination is then made as to whether an edge of the first clock is located within the center portion. In response to such a determination, a number of periods of the second clock signal which occur within one or more periods of the first clock signal is compared to a number derived from the divisor number to generate a frequency selection signal indicative of that comparison. A controlled oscillator circuit generates the second clock signal at the second frequency, wherein the second frequency is specified by the frequency selection signal. To the extent the edge of the first clock is located within either the left or right portions, phase adjustment is made to move the edge towards the center portion.