Patent ID: 7053698

Claim:
A method for extracting a true mean of two signals, comprising: providing the two signals to an n-type buffer input stage and using the n-type buffer input stage to produce a first offset common mode output signal therefrom; providing the two signals to a p-type buffer input stage and using the p-type buffer input stage to produce a second offset common mode output signal therefrom; providing both the first offset common mode output signal and a first feedback signal to an n-type amplifier input stage and using the n-type amplifier input stage to produce a first differential error signal therefrom; providing both the second offset common mode output signal and a second feedback signal to a p-type amplifier input stage and using the p-type amplifier input stage to produce a second differential error signal therefrom; providing the first and second differential error signals to a differential input of a high-gain amplifier output stage and using the high-gain amplifier output stage to produce a true common mode output signal therefrom; providing the true common mode output signal to a feedback stage and using the feedback stage to produce the first and second feedback signals therefrom; and using a transitioning stage to control how much the first differential error signal from the n-type amplifier input stage and the second differential error signal from the p-type amplifier input stage contribute to the differential input of the high-gain amplifier output stage.