Patent ID: 6201447
Filing Date: 2001-03-13
Classification: H03B

Abstract:
A phase synchronization circuit for generating an oscillation signal in synchronism with an input signal, comprising:a phase difference detector for detecting a phase difference between the input signal and the oscillation signal;a loop filter for generating a control voltage corresponding to the detected phase difference;a sweep frequency setting unit for setting a frequency of a sweep wave to a prescribed sweep frequency;a level setting circuit includinga high frequency setting unit that sets the frequency of the sweep wave to a frequency that is higher than the prescribed sweep frequency, anda circuit initially setting the control voltage to a prescribed level;a sweep wave oscillation unit that selectively superposes the sweep wave having the prescribed sweep frequency or the sweep wave having the higher frequency onto the control voltage, the prescribed level being set as a starting point of the sweep wave;a voltage control oscillation circuit for generating the oscillation signal to have a frequency that corresponds to the control voltage; anda selecting unit, which selectively connects said sweep frequency setting unit or said high frequency setting unit with said sweep wave oscillation unit.