A large dynamic range CMOS readout circuit for MEMS vibratory gyroscope

This paper presents a large dynamic range, low noise integrated circuit for readout of a bulk micro-machined vibratory gyroscope. With the proposed sinusoidal chopper technique and the differential-common Duo-Opamp structure, three main objectives are achieved: the low frequency noise cancellation; the biasing of the high impedance nodes in a traditional fully-differential circuit; and the high linearity capacitance-voltage conversion. These characteristics promise an enhanced dynamic range. Furthermore, the demodulation circuit is also a low noise and high linearity design, for the purpose of not deteriorating the overall readout performance. The chip measures 2 times 2.5 mm² in a standard 0.35 mum CMOS process. The results show that the readout circuit can resolve input capacitance variations of 20aF in 100 Hz bandwidth with 106 dB dynamic range from a single 5 V supply.