Patent ID: 8031027

Claim:
A voltage-controlled oscillator (VCO) comprising: a voltage regulator configured to independently receive a first oscillation control signal and a second oscillation control signal to provide a regulated voltage signal which is represented by a regular ratio of combination of the first and second oscillation control signals, the regulated voltage signal being fed back to the voltage regulator; and a delay unit configured to generate an output signal having a frequency varying in response to the regulated voltage signal, wherein the voltage regulator comprises an amplifier that provides a voltage control signal in response to the first oscillation control signal, the second oscillation control signal, and the regulated voltage signal, and wherein the amplifier comprises: a current mirror unit, coupled to a power supply voltage, which includes a first PMOS transistor and a second PMOS transistor; a first input unit, coupled to the current mirror unit at first and second nodes, configured to receive the first oscillation control signal, the regulated voltage signal and a bias voltage to control a first contribution factor of the first oscillation control signal with respect to the regulated voltage signal; and a second input unit, coupled to the current mirror unit at the first and second nodes, configured to receive the second oscillation control signal, the regulated voltage signal and the bias voltage to control a second contribution factor of the second oscillation control signal with respect to the regulated voltage signal, the voltage control signal being provided at the first node.