A 6 nV/√Hz high precision Analog Front-End with sub-µV input offset for MEMS accelerometer

This paper presents a fully integrated high precision Analog Front-End (AFE) as the readout IC for a MEMS capacitive open loop accelerometer. The design consists of continuous time Capacitance-to-Voltage Converter (CVC) followed by a low pass filter. It uses chopping technique to suppress low frequency 1/ƒ noise and achieve low offset. To ensure good PSRR and linearity the CVC employs a two stage OPAMP with telescopic first stage along with cascode compensation technique. The measured result over 10 samples shows that the design achieves an input referred noise of 6 nV/√Hz, input offset of less than 1 µV, linearity of ±0.11% and Turn-On-to-Turn-On (TOTO) repeatability of 3.5 µV while consuming 2 mA current from 1.8-V supply.