Patent ID: 7567124

Claim:
A differential amplifier that receives a differential input signal and provides a symmetrical differential output signal, comprising: a first bias circuit and a second bias circuit receiving as input signals a first end and a second end of the differential input signal, and providing, respectively, a first bias voltage and a second bias voltage; a first load device and a second load device, biased by the first and second bias voltages respectively; wherein the first bias circuit and the second bias circuit are smaller that the first load device and second load device, respectively, a first input device and a second input device, connected in series with the first load device and the second load device, respectively, and receiving as input signals the first end and the second end of the differential input signal, respectively, each of the first input device and the second input device conducting a current in response to its respective input signal; a third input device and a fourth input device, connected in series with the first bias circuit and the second bias circuit, respectively, and receiving as input signals the second end and the first end of the differential input signal, respectively, each of the third input device and the fourth input device conducting a current in response to its respective input signal; wherein the third input device and the fourth input device are smaller than the first input device and the second input device, respectively, and a current source coupled to the first input device and second input device, the current source maintaining a sum of the currents in the first input device and the second input device to substantially constant value.