Advanced readout and control electronics for mems gyroscopes

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2007
Temiz, Yüksel
This thesis reports the development of advanced readout and control electronics for MEMS gyroscopes developed at METU. These gyroscope electronics are separated into three main groups: high sensitive interface circuits, drive mode amplitude controlled self oscillation loops, and sense mode phase sensitive amplitude demodulators. The proposed circuits are first implemented with discrete components, and then integrated on CMOS chips. A self oscillation loop enabling constant amplitude drive mode vibrations independent of sensor parameters and ambient conditions is developed. A fully functional angular rate system, which is constructed by employing this advanced control electronics together with the transresistance amplifier type interfaces and sense mode electronics, is implemented on a dedicated PCB having 5.4x2.4 cm2 area. This system demonstrates an impressive performance far better than the best performance achieved by any angular rate system developed at METU. Bias instability and angle random walk values are measured as 14.3 º/hr and 0.126 º/√hr, respectively. The scale factor of the system is found as 22.2 mV/(º/sec) with a nonlinearity of 0.01%, and a zero rate output of 0.1 º/sec, in ±50 º/sec measurement range. CMOS unity gain buffer (UGB) and transimpedance amplifier (TIA) type resistive and capacitive interfaces are characterized through AC, transient, and noise tests. It is observed that on chip biasing mechanisms properly DC-bias the high impedance nodes to 0 V potential. UGB type capacitive interfaces demonstrate superior performance than TIA counterparts due to stability problems associated with TIA interfaces. CMOS differential drive mode control and sense mode demodulation electronics give promising results for the future performance tests.

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Citation Formats
Y. Temiz, “Advanced readout and control electronics for mems gyroscopes,” M.S. - Master of Science, Middle East Technical University, 2007.