Patent ID: 7463082
Filing Date: 2008-12-09
Classification: G05F

Abstract:
1. A current mirror, comprising: an input circuit, comprising a first transistor having a gate, a drain and a source, wherein current through the first transistor is an input current; an output circuit, comprising a second transistor having a gate, a drain and a source, and having the same voltage difference between the gate and source as the first transistor, wherein current through the second transistor is an output current, and ratio of the output current to the input current is constant; a first operational amplifier, generating an output signal based on the voltage difference between the drain and source of the first transistor and that of the second transistor; a control circuit, adjusting the voltage difference between the drain and source of the second transistor based on the output signal to equalize the voltage difference between the drain and source of the first transistor and that of the second transistor; and a second operational amplifier, controlling the first transistor based on a control voltage and the voltage difference between the drain and source of the first transistor to equalize the voltage difference between the drain and source of the first transistor and the control voltage; wherein the first and second transistors are controlled to operate in triode region by setting the value of the control voltage.