High precision bandgap reference with chopping offset reducing technique

A CMOS bandgap reference using chopping technique for OPAMP offset cancelling is presented in this paper. The OPAMP used in bandgap was intended to improve the precision of the bandgap, but this aim is in some degree reduced by the input referred offset and 1/f noise of the introduced OPAMP. Thus, an effective architecture which contains three pairs of chopping cells is designed to overcome the issue above, while maintaining the stability of the closed feedback loop of the bandgap. The design is fabricated by a 0.18 μm 1P6M CMOS process. Measurements were performed between -55°C and +125°C, the results validated the techniques above, showing different performance of bandgap with/without chopping and with different chopping frequency. Comparing with the conventional design, the proposed architecture effectively improves the accuracy over temperature and process fluctuation.