ABSTRACT This paper presents a low-noise CMOS capacitive sensing amplifier with power ,consumption ,as low ,as 1mW ,for monolithic,CMOS-MEMS inertial sensors. Low-power operation is achieved by using an open-loop, two-stage amplifier topology with fully differential input/output and chopper,stabilization. High chopping ,frequency ,(up to 2MHz) and capacitance matching with,optimal transistor ... [Show full abstract] sizing are used to maximize,signal-to-noise ratio. Offsets due to the ,sensor and circuits are reduced ,by ac ,offset calibration and dc offset cancellation. A pseudo-resistor MOS-Bipolar device is used to establish a stable dc bias atthe sensing electrodes with very low noise. All the electronics, except the capacitor for the low-pass filter following the demodulation, are integrated on the same chip,with ,MEMS inertial sensors. ,A prototype accelerometer,integrated with this ,circuit has ,been fabricated using the TSMC 0.35-µm CMOS process with 3.3-V power ,supply. Experimental results show ,that this interface circuit achieves a gainof 40 dB over the chopper frequency range of 50 kHz to 1 MHz, with an equivalent input offset of about 1 mV. The sensor offset is attenuated by the interface circuit by more than 26 dB.