CMOS MEMS Variable Inductance Accelerometer with Digital Output

• Main Authors: Liu, Hsuan-Wu, 劉軒吾
• Other Authors: Chiu, Yi
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/tkj2m5

碩士 === 國立交通大學 === 電控工程研究所 === 107 === This thesis proposes an inductive accelerometer with digital output, which is fabricated by TSMC 1P6M 0.18μm CMOS MEMS process. In this design, the LC oscillator is composed of a variable spring-inductor which is connected with a high Q inductor in series and is paralleled with a MIM capacitor. When an external acceleration acts on the chip, displacement of the mass occurs and, at the same time, the spring-inductor area and inductance value change. The change of the inductance value causes the oscillation frequency changes. Furthermore, the changes of frequency and acceleration are in direct proportion. Therefore, the acceleration can be detected by the frequency change. In addition, a counter circuit is added in the chip. The oscillator output is connected to the counter for frequency counting which converts the frequency output to the digital output for subsequent measurement and application. The counter also avoids using the external instruments that may cause additional parasitic effects and affect sensor performance. In this thesis, the measurement result shows the oscillation frequency is 1.38 GHz and sensitivity is 37.8 kHz/g.