Patent ID: 7602227

Claim:
A differential amplifier circuit, comprising: first and second load stages each having a predetermined resistance value; a main differential amplifier unit having a first differential stage that forms a differential pair in such a way as to amplify a difference between a first input voltage and a second input voltage, and a constant current source, which has a predetermined current driving capability and is connected serially between a power source voltage terminal and a ground terminal; and an auxiliary differential amplifier unit having a second differential stage that forms a differential pair in such a way as to amplify a difference between the first input voltage and the second input voltage, wherein the first input voltage is connected between the first load stage and the ground, and the second input voltage is connected between the second load stage and the ground, wherein the first differential stage has first and second transistors forming the differential pair, and the second differential stage has cascoded-connected third and fourth transistors and cascoded-connected fifth and sixth transistors forming the differential pair, wherein gates of the third and the fifth transistors are connected to ground and a bias voltage is applied to gates of the fourth and sixth transistors.