The invention discloses a low-output-
ripple ultralow-offset-
voltage operational amplifier and a working method thereof. The low-output-
ripple ultralow-offset-
voltage operational amplifier comprises a first
chopper circuit, a first-stage
operational amplifier additionally provided with an offset
voltage adjusting circuit, a second
chopper circuit, a notch filter, a second-stage operational
amplifier and a third-stage operational
amplifier which are sequentially connected. The offset voltage adjusting circuit trims the
input offset voltage of the first-stage operational
amplifier to hundreds of microvolts and then outputs the offset voltage to the second
chopper circuit; the first chopper circuit and the second chopper circuit are used for modulating the offset voltage of the first-stage operational amplifier to a chopping frequency, and then the
ripple voltage at the chopping frequency is filtered by the notch filter; the first-stage operational amplifier is designed to be a high-
gain amplifier so as to restrain
input offset voltage errors caused by the second-stage operational amplifier and the third-stage operational amplifier. According to the invention, low output ripple voltage and ultralow
input offset voltage can be realized only by using the wave trap with a small area.