US Patent 7808321 Amplifier circuit

An amplifier circuit includes first and second transistor circuits, a current supply unit, and a current sink unit. The first transistor circuit is operatively responsive to a first input signal, and the second transistor circuit is operatively responsive to a second input signal. The current supply unit includes at least two symmetrically configured current mirrors connected to a source voltage, and provides a first current to the first transistor circuit and a second current to the second transistor circuit, where a magnitude of the first and second currents is the same. The current sink unit is responsive to an enable signal to sink the first and second currents supplied to the first and second transistor circuits to a ground voltage.