Advanced readout and control electronics for mems gyroscopes

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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This thesis presents the RF and mechanical design of a metal-to-metal contact RF MEMS switch. Metal-to-metal contact RF MEMS switches are especially preferred in low frequency bands where capacitive switches suffer from isolation due to the limited reactance. Frequency band of operation of the designed switch is from DC to beyond X-band. Measured insertion loss of the structure is less than 0.2 dB, return loss is better than 30 dB, and isolation is better than 20 dB up to 20 GHz. Isolation is greater than 2...
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In this thesis, optimum current injection strategy for Magnetic Resonance Electrical Impedance Tomography (MREIT) is studied. Distinguishability measure based on magnetic flux density is defined for MREIT. Limit of distinguishability is analytically derived for an infinitely long cylinder with concentric and eccentric inhomogeneities. When distinguishability limits of MREIT and Electrical Impedance Tomography (EIT) are compared, it is found that MREIT is capable of detecting smaller perturbations than EIT. ...
Citation Formats
Y. Temiz, “Advanced readout and control electronics for mems gyroscopes,” M.S. - Master of Science, Middle East Technical University, 2007.