Patent ID: 7053703

Claim:
An operational amplifier circuit, comprising: a first inverted amplifier circuit that receives a first input signal; a second inverted amplifier circuit that receives a second input signal; a third inverted amplifier circuit that receives an estimated common-mode output signal and an output signal of said first inverted amplifier circuit and outputs a first output signal and a second output signal; a fourth inverted amplifier circuit that receives the estimated common-mode output signal and an output signal of said second inverted amplifier circuit and outputs a third output signal and a fourth output signal; a first non-inverted amplifier circuit that receives the estimated common-mode output signal and outputs an output signal, the output signal of the first non-inverted amplifier circuit fed back to the output signal of the first inverted amplifier circuit; and a second non-inverted amplifier circuit that receives the estimated common-mode output signal and outputs an output signal, the output signal of the second non-inverted amplifier circuit fed back to the output signal of the second inverted amplifier circuit, wherein adding the second output signal and the fourth output signal generates the estimated common-mode output signal.