Image Number 3 for United States Patent #7915948.
A differential amplifier circuit receives a pair of input signals to develop an output signal. First and second MOS transistors have commonly-connected gates and sources. A third MOS transistor has a drain connected to the commonly-connected gates, and a source connected to the first MOS transistor's drain. The third MOS transistor's gate is connected to a constant voltage source. A constant current source is connected to the third MOS transistor's drain. A first terminal, connected to the first MOS transistor's drain and to the third MOS transistor's source, provides an input current. A second terminal, connected to the first and second MOS transistors' commonly-connected sources, provides a common reference. A third terminal, connected to the second MOS transistor's drain, provides an output current.