Patent ID: 8773198

Claim:
An auto-zero amplifier, comprising: an amplifying circuit, comprising a first input end and a second input end, for receiving a first input signal in a first period and receiving a second input signal in a second period, respectively; and comprising a first output end, for generating a first output signal according to the first input signal in the first period and for generating a second output signal according to the second input signal in the second period; a first switch, coupled between the first output end and a capacitor, for charging or discharging the capacitor to a voltage with the first output signal when the first switch is conducted, and for keeping the capacitor at the voltage when the first switch is not conducted; and a difference signal generating circuit, comprising a third input end coupled with the first output end of the amplifying circuit and a fourth input end coupled with the capacitor, for generating a first difference signal of the first output signal and the second output signal, a multiple of the first difference signal, a part of the first difference signal, and/or a digital value of the first difference signal at a second output end according to the second output signal and the voltage of the capacitor in the second period.