Patent ID: 6900677

Claim:
A differential charge pump comprising: a first driver for receiving a first input signal and generating a first output signal; a second driver for receiving a second input signal and generating a second output signal; a third driver for receiving an inverted signal of the second input signal and generating a third output signal having the same voltage level as the first output signal; a fourth driver for receiving an inverted signal of the first input signal and generating a fourth output signal having the same voltage level as the second output signal; a first transistor having a gate connected to a first bias voltage, a source to which the first output signal is applied, and a drain connected to an output signal of a first differential charge pump; a second transistor having a gate connected to the first bias voltage, a source to which the second output signal is applied, and a drain connected to an output signal of a second differential charge pump; a third transistor having a gate connected to a second bias voltage, a source to which the third output signal is applied, and a drain connected to an output signal of the first differential charge pump: a fourth transistor having a gate connected to the second bias voltage, a source to which the fourth output signal is applied, and a drain connected to the output signal of the second differential charge pump; a reference voltage generating circuit for generating a reference voltage; a reference current generating circuit for generating a reference current and having its output connected to the second bias voltage; a common mode feedback circuit for receiving the output of the reference voltage, the output signal of the first differential charge pump and the output signal of the second differential charge pump as inputs and generating the first bias voltage; and a fifth transistor having a drain and a gate connected to the second bias voltage, and a source connected to the ground voltage.