Patent ID: 7319350
Filing Date: 2008-01-15
Classification: H03L

Abstract:
1. A lock-detection circuit configured to detect whether or not an oscillation-output signal synchronizes with a reference signal, comprising: a voltage controlled-oscillation circuit that transmits the oscillation-output signal; and a phase detection circuit that detects a phase difference between the reference signal and the oscillation-output signal; wherein the phase detection circuit detects whether the reference signal falls within the range corresponding to a difference between a first phase of a first output signal and a second phase of a second output signal, where the first output signal advances by as much as a first predetermined phase amount with reference to the oscillation-output signal and the second output signal delays by as much as a second predetermined phase amount with reference to the oscillation-output signal, wherein the voltage-controlled-oscillation circuit is provided as a ring-oscillation circuit including a plurality of inverters connected to one another in a ring shape, wherein the first output signal is transmitted from a second inverter provided ahead of a first inverter that transmits the oscillation-output signal by as much as a first predetermined number of stages, and the second output signal is transmitted from a third inverter provided at the rear of the first inverter by as much as a second predetermined number of stages.