VCO circuit with wide output frequency range and PLL circuit with the VCO circuit

摘要

A voltage-controlled oscillating circuit according to the present invention includes: a drive voltage generating circuit outputting a bias voltage according to a control voltage; and a ring oscillator circuit receiving supply of the bias voltage to operate. The drive voltage generating circuit generates the bias voltage using a feedback circuit formed by an operational amplifier receiving supply of a power source voltage to operate. Therefore, an influence of a high frequency component overlapped on the power source voltage, that is an influence of noise, is suppressed, thereby enabling stable generation of an output clock having a small variation in phase.