CLOCK RECOVERY PHASE LOCKED LOOP CIRCUIT

摘要

PURPOSE:To make the pull-in operation stable by using an analog gate circuit so as to supply phase error information to an LPF for a time of the phase error information. CONSTITUTION:The analog gate circuit 4 is interposed between an output terminal of a phase comparator circuit and an LPF 5 and an output of a T/2 pulse generating circuit 2 controls the analog gate. The T/2 pulse generating circuit 2 is started by the edge of the input signal to generate a pulse of T/2. The LPF 5 consists of a passive filter, an impedance buffer and an offset bias supply circuit. The phase error information is fed to the LPF 5 by a time having the phase information and the output of the phase synchronizing circuit is brought into a high impedance in other times.