Patent ID: 7446597

Claim:
A voltage-controlled current source, comprising: a first impedance circuit, comprising a first terminal coupled to a first common voltage; a first amplifier, comprising a first terminal coupled to a second terminal of the first impedance circuit, a second terminal coupled to a control voltage, and an output terminal; a first transistor, comprising a gate coupled to the output terminal of the first amplifier and a first source/drain coupled to the second terminal of the first impedance circuit; a current mirror, coupled to a second source/drain of the transistor and comprising a current output terminal, wherein a current output by the current output terminal is proportional to a current flowing through the first transistor; and a third amplifier disposed between the first amplifier and the control voltage and comprising a first terminal coupled to the control voltage, a second terminal for receiving a second predetermined voltage, and an output terminal coupled to the second terminal of the first amplifier.