Phase comparator with two different comparator - characteristics

摘要

PURPOSE:To reduce the number of components in use and power consumption by constituting said two phase comparator circuits of one basic circuit and a peripheral circuit in a phase comparator in which the two phase comparator circuits are used selectively, and switching the connection of the peripheral circuit to the basic circuit. CONSTITUTION:A phase comparator 10 consists of a basic circuit 11 and a peripheral circuit connected switchingly to the basic circuit 11. Then the connection of the peripheral circuit to the basic circuit 11 is switched to select switchingly the two phase comparison characteristics. When the phase of a comparison reference signal is led from the phase of the comparison input signal, a delay control signal DOWN retarding the VCO output phase is outputted. Conversely, when the phase of the VCO output is retarded than the phase of the comparison input signal, a lead control signal UP is outputted. Thus, one set of the basic circuit requiring comparatively many components in use is enough and a multiplexer having been required for the conventional circuit is not required, then the number of components in use is reduced.