A CMOS-MEMS Inductive Pressure Sensor with Low Q Inductor and Oscillator Circuit

• Main Authors: Tsai, Pei-Lun, 蔡佩倫
• Other Authors: Yi, Chiu
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/sz23u8

碩士 === 國立交通大學 === 電機工程學系 === 107 === Pressure sensors measure the pressure difference between a reference pressure and the pressure we want to sense. There are various kinds of pressure to be measured, such as air pressure, hydraulic pressure etc. Pressure sensors convert the pressure difference to an electrical quantity and then a back-end circuit converts it into electronic signals as outputs. This thesis uses the UMC and TSMC 0.18μm CMOS processes and MEMS post processes provided by the National Chip Implementation Center (CIC) to implement an inductive pressure sensor with a low Q inductor. The back-end circuit is an oscillator circuit with a digital output. The sensing inductor is deformed by pressure so the inductance value changes and the oscillation frequency also changes. So, the oscillation frequency change is used to detect the pressure. In this thesis, three devices were designed and fabricated. Both Sample I and Sample II were planar inductor test structures fabricated by UMC 0.18μm CMOS-MEMS processes. Sample III was an inductive pressure sensor with back-end sensing circuits fabricated by TSMC 0.18μm CMOS processes. The measurement results showed that the pressure sensing was not linear and the stability of the oscillators was not good. The sensitivity calculated based on stable measured data was found to be -116.7 kHz / atm and -362.1 kHz / atm for increasing and decreasing pressure between 0.7 atm to 1.3 atm, respectively.