Digital second-order CDR circuits

摘要

A method for performing a clock and data recovery includes providing data and a clock; determining early/late values of the data to generate a first-order phase code using the data and the clock; and accumulating first-order phase codes retrieved from different finite state machine (FSM) cycles to generate a second-order phase code. A plurality of candidate total phase codes is generated from the second-order phase code. A multiplexing is performed to the plurality of candidate total phase codes to output one of the plurality of candidate total phase codes as a total phase code. The multiplexing is controlled by the first-order phase code. A brake machine may be implemented to prevent over-compensation of phases.