Phase-locked loop circuit

A voltage controlled oscillator is configured to include a plurality of variable delay circuits that are connected to one another so as to form a ring. Output fixing units each of which fixes, when the voltage controlled oscillator stops operating, the output of a corresponding one of the variable delay circuits are provided. As a result, even if the voltage controlled oscillator that operates by following the frequency of an input clock has changed into an operation stop state, because the output fixing units fix the outputs of the variable delay circuits , the output of the voltage controlled oscillator is prevented from being in an inconstant state. Thus, it is possible to ensure that the voltage controlled oscillator oscillates properly when the voltage controlled oscillator resumes or starts its operation.