A 2μV low offset, 130 dB high gain continuous auto zero operational amplifier

This paper discusses the design of a Continuous Time Auto Zero amplifier (CTAZ) to reduce the offset voltage for sensing very small analog signals. The CTAZ simulation results show that the design is able to achieve an offset of around 2μV for light sensing application, where offset is one of the critical parameters. The designed amplifier has a very high loop gain of 131 dB, a gain bandwidth product of 1.5 MHz, PSRR (Power Supply Rejection Ratio) of 131 dB, and noise floor of 0.2μV/√Hz and consumes 27μW of power. The Operational Amplifier (OP-AMP) was designed in 180nm CMOS process with a supply voltage of 1.8 V.