Patent ID: 6392497
Filing Date: 2002-05-21
Classification: H03L

Abstract:
A phase-locked loop circuit comprising:a phase comparator for outputting an error signal corresponding to a phase difference between a reference signal and an output signal; a charge pump for outputting a voltage signal corresponding to the error signal fed from said phase comparator; a lowpass filter for passing a low frequency component of the voltage signal fed from said charge pump; a voltage-controlled oscillator; and a controller including a series circuit having a first transistor, second transistor, a third resistor and a first resistor connected in series in this order, a second resistor connected in parallel with a series connection of said second transistor and said third resistor, and an operational amplifier having its non-inverting input terminal connected to an output terminal of said lowpass filter, its inverting input terminal connected to a connected point of said third resistor and said first resistor, and its output terminal connected to a gate of said second transistor.