單晶片微機電陀螺儀整合低功耗可調增益介面讀出電路之設計

Abstract

本論文提出可於標準CMOS 0.18μm 1P6M電路製程下，製造完成電容式角速度感測微機電陀螺儀結構與低功耗離散時域相關雙採樣技術可調增益介面讀出電路。在此標準製程下，可以將驅動和介面讀出電路整合微機電陀螺儀於單晶片上，而不需要晶圓代工廠外額外的後製程步驟，能大幅節省晶片面積。介面讀出電路採用離散時域相關雙採樣技術消除低頻雜訊與誤差，結合低功耗低雜訊可調整增益放大器調整動態範圍。 微機電陀螺儀其驅動模態量測結果為 6.1 KHz而感測模態量測結果為9.6 KHz及15.4 KHz，品質參數約為300與190，陀螺儀操作線性範圍約為 ±100 °/sec且靈敏度為1.4aF/deg/sec。整體介面讀出電路工作在 1.8 V 的工作電壓下消耗約 0.2 mA 電流，利用全差動可調增益放大器，靈敏度可調整範圍為2.55 mV/aF 至 20.4 mV/aF，此界面讀出電路在 500 KHz 的取樣頻率下可達到約60 dB的訊號雜訊比。

A Micro Electro Mechanical Systems (MEMS) gyroscope with low power tunable-gain interface circuit that can be manufactured and monolithically integrated in the ASIC-compatible 0.18μm standard CMOS process is proposed for measuring angular rate. It could be monolithically integrated with CMOS driving and readout circuitry without the need of any post-processing after fabrication from the foundry. Interface circuit adopts Correlated Double Sampling (CDS) to suppress low frequency noise and compensate DC offset. The measurement results of the proposed gyroscope driving frequency is 6.1 KHz and sensing frequencies are 9.6 KHz and 15.4 KHz. The calculated Q-factor were 300 and 190, and the gyroscope sensing linear range is within ±100 °/sec and the sensitivity caused by Coriolis force is 1.4aF/°/sec. The chip draws 0.2 mA from a 1.8-V supply, the tunable sensitivity can be adjusted from 2.55 mV/fF to 20.4 mV/fF by programmable-gain amplifier. The interface circuit provide 60 dB signal to-noise ratio (SNR) under 500 KHz sampling rate.