Phase frequency detector with a narrow control pulse

Abstract

A phase frequency detector with a narrow control pulse comprises mainly two substantially equivalent phase latches with a narrow control pulse, and a reset signal generating unit. Each phase latch of a narrow control pulse has a clock pulse input end and a signal output end. Both latches also be connected to the reset signal generating unit. The logic value of each signal output end is decided by which clock pulse input appears first. The reset signal generating unit decides whether or not to generate a reset signal according to the logic values of both signal output ends. The reset signal is then sent to both phase latches of a narrow control pulse, if generated. The present invention can be implemented by a simple circuit. Comparing with the RS NAND PFD or master-slave D PFD, the PFD of the invention has the advantages of faster speed, saving more power and smaller IC chip area. Comparing with dynamic PFD, because the PFD of the invention has a feedback circuit, the storage charges of internal nodes will not be lost due to the leakage current and therefore the working frequency range is wider.