A C/V Converter for MEMS Gyroscope Readouts Featuring a Single Stage Class AB OTA

In this paper, we present a fully differential single stage charge-to-voltage (C/V) converter with a class AB output stage for gyroscope readout circuits. The proposed amplifier offers low noise and low power consumption by using a current reuse architecture in the OTA core while also providing a rail to-rail output swing for a good signal-to-noise ratio (SNR). I this work we benefit from a single stage amplifier which has the advantage of requiring no compensation capacitance, therefor (reducing the overall area. Moreover, having a class AB output stage allows us to reduce the needed quiescent current compare to a class A output stage while offering a high voltage swing at the output. In order to ensure that the proposed amplifier fulfills the sensor frontends specifications, extensive simulations have been carried out over a temperature range from (−5°C to 70°C) including process, voltage and micro electro-mechanical system (MEMS) variations. The simulated power consumption is below 37 $\mu$W from a 1.6 V supply and the input-referred noise stays below 35 nV/$\sqrt{\mathrm{H}\mathrm{z}}$ from 35 kHz to 10 MHz. The C/V is designed in a 40 nm CMOS process and offers a gain drift of 0.4% from −5°C to 70°C, a phase drift of below 3.5 mrad and a total harmonic distortion (THD) of below 1.5% for an output swing of 1.2 $\mathrm{V}_{\mathrm{p}\mathrm{p}}$ over all process corners while consuming an area of $145 \times 165\mu \mathrm{m}^{2}$.