VCO CIRCUIT WITH WIDE OUTPUT FREQUENCY RANGE AND PLL CIRCUIT WITH THE VCO CIRCUIT

摘要

PURPOSE: VCO circuit with wide output frequency range and PLL circuit with the VCO circuit is provided to realize configurations of a voltage-controlled oscillating circuit having a wide output frequency range and capable of suppressing an influence of power source noise and of a phase-locked loop circuit equipped with the voltage-controlled oscillating circuit. CONSTITUTION: A voltage-controlled oscillating circuit receiving supply of a power source voltage to operate, comprising: a voltage generating circuit(11) setting a voltage level of a bias voltage according to a control voltage inputted from outside, the voltage generating circuit(11) including an operational amplifier(12), which is an amplifier of a single-stage configuration, and receiving supply of the power source voltage to operate, the operational amplifier(12) having first and second input terminals electrically coupled with one of the control voltage and a reference voltage and the other of the voltages, respectively, and an output terminal outputting the bias voltage, and the voltage generating circuit(11) further including a feedback portion coupled between the output terminal and one of the first and second input terminals; and a ring oscillator circuit(20) generating a clock having a frequency corresponding to the bias voltage, and having an odd-number of inverters, interconnected in a closed ring, and each inverter receiving supply of the bias voltage to operate