Locked loop circuit and method with multi-phase synchronization

Abstract

A locked-loop circuit includes phase synchronization circuitry to synchronize a DCO clock phase to a reference clock phase. Sampling circuitry sequentially samples the reference clock with each of N sampling clocks having offset phases, a first one of the N sampling clocks comprising a master sampling clock. Edge detection logic accumulates phase information from the multiple sampling clocks and determines, based on the accumulated phase information, whether any of the sampling clocks other than the master sampling clock correspond to edge detection signals that occurred early with respect to a rising edge of the master sampling clock. Index logic generates index values for any of the determined early edge detection signals. The index logic transfers the generated index values to a master phase transfer logic unit. Phase adjust logic adjusts the master clock phase based on a selected one of the generated index values.