Patent ID: 8089317
Filing Date: 2012-01-03
Classification: H03L

Abstract:
1. A phase-locked loop circuit, comprising: a phase detection unit which detects phase information of an input signal; a loop filter unit which includes a series circuit of a resistor circuit and a capacitor circuit, a terminal of the capacitor circuit opposite the resistor circuit being connected to a reference point; a first pulse-current output unit which supplies a differential pulse current to one of the resistor circuit and the capacitor circuit from a positive-phase output terminal and a negative-phase output terminal, the differential pulse current corresponding to the phase information output from the phase detection unit; a second pulse-current output unit which supplies a single-end pulse current to the other one of the resistor circuit and the capacitor circuit from a single output terminal, the single-end pulse current corresponding to the phase information output from the phase detection unit; an oscillating unit capable of varying an oscillation frequency in accordance with a component obtained by combining a voltage generated at both ends of the one of the resistor circuit and the capacitor circuit on the basis of the differential pulse current supplied from the positive-phase output terminal and the negative-phase output terminal of the first pulse-current output unit and a voltage generated at both ends of the other one of the resistor circuit and the capacitor circuit on the basis of the single-end pulse current supplied from the single output terminal of the second pulse-current output unit; and a calibration unit which obtains information of an oscillation gain in actual operation and corrects an oscillating operation of the oscillating unit on the basis of a difference between the oscillation gain in actual operation and a target oscillation gain, the oscillation gain in actual operation representing a characteristic of oscillation frequency versus input signal of the oscillating unit and being obtained using oscillation control signals for correction with predetermined magnitudes on the basis of a difference between actual oscillation frequencies under the oscillation control signals, wherein the calibration unit includes wherein the correction control signal generator includes a series circuit of a resistor element through which the bias current for correction flows and a transistor having a temperature characteristic that matches a temperature characteristic of a transistor included in the oscillating unit, and wherein the reference resistor and the resistor element through which the bias current for correction flows have substantially the same temperature variation characteristic.