Operational Transconductance Amplifier Design Integration for MEMS Accelerometer Application in 65nm CMOS Technology

Microelectromechanical System (MEMS) Sensor technology has revolutionized the electronics industry with its wide array of applications from wearable electronics to precision instrument for biomedical applications. However, two of the most inherent problems with these sensors are low capacitance-to-voltage conversion of sensors and its high susceptibility to noise. Since MEMS sensors have been developed over the years, and as to meet the surging market demands of interface circuits, the need for upgrading its features has led to the integration of more complex designs. This paper presents an integrated approach for MEMS switched capacitor-based interface which is implemented using a Low Noise Operational Transconductance Amplifier (OTA) design and a digital clock control block implemented in 65nm CMOS Process. The OTA design composes of a noise buffer preamplifier cascaded to a conventional folded cascode amplifier topology. The OTA design obtained parameters values with an open loop gain of 65.5 dB, Unity gain bandwidth of 8.48 MHz, PSRR+ of 65.2 dB and PSRR-of 93.3 dB and a CMRR of 115 dB. Input referred Noise is at 18.369 nV/√Hz. MEMS sensors signal are initialized at the input as MEMS sensors are beyond the scope of this study. With a MEMS noise model, the obtained noise cancellation ability of the proposed amplification and noise cancellation network is known to be 88.765%. The overall circuit covers a chip area of 242 um×705 um.