An area-efficient self-trimming technique for precision chopper-stabilized instrumentation amplifier (IA) is presented. The amplifier uses a reconfigurable differential pair for the input stage and it is automatically configured to reduce the mismatch of the differential pair, suppressing the chopper ripple. To confirm the effectiveness of the proposed scheme, an IA with the complete calibration logic is fabricated in a standard 180-nm CMOS and achieves active area, less than offset voltage, input-referred noise, and current consumption. The noise efficiency factor of the amplifier is 7.2.