Patent ID: 7466208

Claim:
A voltage controlled oscillator circuit comprising: a control portion to which a first voltage is inputted and from which a second voltage corresponding to the first voltage is outputted; a current source portion to which the second voltage is inputted and from which a current corresponding to the second voltage is outputted; and an oscillator circuit to which the current is inputted and from which a signal with a frequency in accordance with the current is outputted, wherein the control portion includes an adjusting circuit, wherein the adjusting circuit changes the second voltage in accordance with change of a power supply voltage, wherein the control portion includes a first transistor, a second transistor, and a third transistor connected in series with the first transistor, wherein the adjusting circuit includes the second transistor, wherein the third transistor is diode-connected, wherein a drain current of the third transistor is the sum of a drain current of the first transistor and a drain current of the second transistor, wherein the first voltage is inputted to a gate of the first transistor, wherein the second voltage is outputted from a drain of the first transistor, wherein a third voltage is inputted to a gate of the second transistor, wherein the third voltage changes in accordance with chance of the power supply voltage, wherein both of the first transistor and the second transistor are n-channel transistors, and wherein the third voltage decreases when the power supply voltage is increased, whereas the third voltage increases when the power supply voltage is decreased.