Abstract: A phase lock loop system that includes a voltage controlled oscillator. The output of an integrator provides the voltage to a tuning port for determining the precise frequency and phase of the oscillator. In response to a change in frequency, the input to the integrator is switched off at the precise time that its output voltage reaches the value for the proper phase relationship at the new frequency. The output of a low pass filter fed by the loop's phase detector determines such precise time. At said precise time, the stabilized condition of the loop is sensed and corrected for minor deviations.