A Study of low noise capacitor readout circuit on MEMS-Pressure device

• Main Authors: Kai-Si Chen, 陳楷錫
• Other Authors: 黃榮堂
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/92w6tg

碩士 === 國立臺北科技大學 === 機電整合研究所 === 99 === In this thesis, a new type of capacitor sensor composed of pressure and CMOS circuitry is proposed. The capacitor variation can be measured directly by means of the proposed sensing circuit, which is composed of an impedance amplifier and a switched-capacitor amplifier. The goal of the designed sensor is used to detect the pressure of blood vessel. Furthermore, an array-typed MEMS-pressure sensor can be to detect blood vessel pressures in various pressure ranges, and it is desired to become a wearable or an implantable device. The sensing capacitor range of the proposed sensor is about 1~200 fF. By using readout circuits and comparing the waveforms generator (in sine wave), we can calculate the capacitor variation of MEMS-pressure sensor. As to measurement of capacitor, we chose an integrator to convert the Pressure-Sensor output capacitor into a voltage in this study. The sensing signals are then amplified and readout with switched-capacitor (SC) circuit. According to the simulation, the proposed system is implemented in TSMC 0.35 μm 2P4M technology. The chip area is roughly 1.796*1.814 with power supply of 3.0V. Through simulation, the CMOS switching frequency is 33KHZ as the input signal of 1 kHz sine waves. The proposed structure has a capacitor measuring range from 1 fF to hundreds of fF. This study successfully presents a smart sensor which can detect a very small capacitor variation of MEMS-pressure sensor.