Patent ID: 6642701
Filing Date: 2003-11-04
Classification: G01R,H03L

Abstract:
A testing device for a phase-locked loop including a phase comparator, a charge pump, a loop filter and a voltage-controlled oscillator, comprising:a reset circuit resetting the phase-locked loop by disconnecting the charge pump from the loop filter and providing an alternative discharge path for the loop filter; an input circuit receiving a feedback signal from an output of the phase-locked loop and a control signal, producing a combination signal from the received signals and inputting the combination signal to the phase-locked loop, the combination signal, together with a reference signal, causing the phase-locked loop to perform one of charging up the loop filter, discharging the loop filter and a normal operation; an output circuit outputting a signal with a frequency corresponding to an output of the voltage-controlled oscillator in cases that the phase-locked loop charges up the loop filter, that the phase-locked loop discharges the loop filter and that the phase-locked loop performs the normal operation; and a connection control circuit controlling connection between a digital circuit and an analog circuit of the phase-locked loop.