振動式微環形陀螺儀之感測電路設計

Abstract

本論文之目的在探討微小環形諧振式陀螺儀的感測電路設計。微小環形諧振式陀螺儀是利用微機電製程所製造的微小結構，透過震動時結構的改變引起兩結構間的電容值改變，而這個電容值非常的微小，通常在fF等級。若是透過打線將訊號線外接到電路板上可能因訊號太小雜訊過大而無法量測出來，因此本論文將量測電路積體化，藉此減少打線的距離以及電路的雜訊。

目前被廣泛的使用在電容量測的電路有同步偵測電路以及切換式電容電路。切換式電容電路需要複雜的時脈電路以及有MOS作為開關所產生的雜訊，而同步偵測電路不需使用到開關以及複雜的時脈電路，並且可以消除放大器的寄生電容問題以及減少1/f的雜訊。所以選用同步偵測電路來作為這次的設計架構。

本論文將對整個同步偵測電路做介紹、電路分析、設計以及模擬。採TSMC 0.35um, 2P4M, Mixed-mode, 3.3，5V的製程參數來模擬及實現。

Probing into design of the capacitance detecting circuit for the micro gyroscope is the purpose of this thesis. Micro gyroscope is the small structure made with MEMS process. The sensing signal of this gyroscope due to the gap changes while the gyroscope shakes, then the capacitive value between the gap changes too. The capacitive value is very small and usually of fF grade. If we connect this signal to the sensing circuit on PCB, this signal can not be examined out because the signal/noise ratio is too small. So in this thesis, we try to design the capacitance detecting circuit in integrated circuit technology in order to reduce the noise of the sensing circuit. Presently, the popular method in capacitance detecting circuit contains of the synchronous detection circuit and the switched capacitor sensing circuit. The switched capacitor sensing circuit needs complicated clock circuits and suffers from the noise of the MOS switch. However, the synchronous detection circuit doesn’t. Besides, it can cancel the parasitic capacity and the 1/f noise. So we select the synchronous detection circuit for use. This thesis contains of examining circuit structure, circuit analysis, design, simulation and realization for the synchronous detection circuit with the model of TSMC 0.35um , 2P4M , Mixed-mode, 3.3, 5V.