A chip design of novel chopper stabilized operational amplifier was presented, chopper-wave modulation and demodulation was used in this architecture, and its 1/f noise was decreased largely. To extend input common mode voltage range, a novel rail-to-rail differential amplifier was adapted in the input stage. The range of input common mode voltage was from zero to power supply, and it only consumed about 22 mu A current. When input signal frequency was 1 KHz, and the output signal THD was only 0.01%.