Patent ID: 7348824

Claim:
An auto-zero circuit, comprising: a first set of circuits for implementing a first auto-zero phase, wherein the first set of circuits comprises a first differential amplifier and a first feedback path coupled between an output of the first differential amplifier and an input of the first differential amplifier; a second set of circuits for implementing a second auto-zero phase, wherein the second set of circuits comprises a second differential amplifier and a second feedback path directly coupled between an output of the second differential amplifier and the input of the first differential amplifier and wherein the second feedback path comprises an attenuation capacitor for reducing charge injection error and noise error of the auto-zero circuit and a holding capacitor for holding a voltage to be used to correct charge injection error introduced by the first feedback path, wherein the first auto-zero phase and the second auto-zero phase are performed sequentially; and a third set of circuits for implementing a third auto-zero phase, wherein the third set of circuits comprise a third feedback path for reducing finite gain error and noise error of the auto-zero circuit, and wherein the third feedback path is coupled between the output of the second differential amplifier and the input of the first differential amplifier.