5th order sigma delta MEMS accelerometer system with enhanced linearity

Aykutlu, Ulaş
This thesis reports the linearity enhanced 5th order sigma delta MEMS accelerometer readout circuit utilizing varying gap type capacitive MEMS accelerometer sensor. While varying gap type capacitive MEMS accelerometers provide high sensitivity, high reliability and high shock tolerance suitable for navigation grade applications, these types of mechanical sensors suffer from the non-linear input to output relation even in the closed loop operation due to the limited loop gain. Thus, this research aims to improve the linearity performance and eliminate the non-linear behavior of mechanical sensor by employing PI controller in the sigma delta interface circuit designed previously in METU-MEMS Center. In order to achieve this goal, firstly the non linear behavior of the capacitive MEMS accelerometer is examined. Then, MATLAB-Simulink simulations are performed to demonstrate the enhancement in the linearity performance of the accelerometer system taking advantage of PI controller in the loop. Programmable PI controller which enables integration of various MEMS accelerometer with the readout circuit is implemented carefully using XFab 0.35µm CMOS process to guarantee low noise and bias instability while providing enhanced linearity performance. Designed readout is integrated with the MEMS accelerometer which is fabricated at METU-MEMS Center in a 16-pin metal package to perform system level performance tests.


High performance closed-loop analog readout circuit for capacitive MEMS accelerometers
Terzioğlu, Yunus; Akın, Tayfun; Department of Electrical and Electronics Engineering (2015)
In this thesis, a closed-loop analog readout circuit for capacitive MEMS accelerometers is introduced. The detailed analysis of the dynamics of the proposed accelerometer is presented along with the associated simulation models. The theoretical investigation of each building block of the accelerometer is also presented in detail and supported by the corresponding formulas. The implemented accelerometer is shown to satisfy the estimated performance parameters with measurements conducted using various test se...
Development of an integrated resonant MEMS temperature sensor
Köse, Talha; Azgın, Kıvanç; Akın, Tayfun; Department of Mechanical Engineering (2016)
This thesis presents the design, fabrication and characterization of a high performance, integrated, resonant MEMS temperature sensor, and temperature compensation of a capacitive MEMS accelerometer. Two different double-ended-tuning-fork (DETF) type resonator designs are developed and characterized for temperature sensing. The strain-amplifying beam structure is added to the DETF resonators in order to enhance thermal strain induced on the DETF tines due to the different thermal expansion coefficients of t...
Resonance-based MEMS temperature sensors for temperature compensation of mems capacitive accelerometer
Demirhan, Gülşah; Akın, Tayfun; Department of Electrical and Electronics Engineering (2016)
The idea of the proposed study is using the resonator structure as a temperature sensor together with controller circuitry. That is to say, the study consists of two branches; one is PI controller output which would be used as a temperature sensor and the other is preamplifier output which would be used as carrier generator to the accelerometer readout circuitry. The proposed resonator is analyzed in detail in terms of dynamics, simulation models and theoretical investigations. The implemented resonator is ...
Noise analysis and characterization of a sigma-delta/capacitive microaccelerometer
Külah, Haluk; Yazdi, N; Najafi, K (2006-02-01)
This paper reports a high-sensitivity low-noise capacitive accelerometer system with one micro-g/root Hz resolution. The accelerometer and interface electronics together operate as a second-order electromechanical sigma-delta modulator. A detailed noise analysis of electromechanical sigma-delta capacitive accelerometers with a final goal of achieving sub-jig resolution is also presented. The analysis and test results have shown that amplifier thermal and sensor charging reference voltage noises are dominant...
Design of an X-band 3-bit RF MEMS constant phase shifter
Kuzubaşlı, Ahmet; Akın, Tayfun; Demir, Şimşek; Department of Electrical and Electronics Engineering (2016)
This thesis presents a 3-bit 180° constant phase shifter design implementing Co-Planar Waveguide (CPW) and RF MEMS variable capacitors with ±1.8% accuracy at 10 GHz and ±5.8% maximum peak error between 9-11 GHz. The phase shifter with minimum phase errors is determined by considering exemplary circuit simulations of different phase shifter types designed with a novel in-house RF MEMS fabrication process [1] parameters. Due to its wide-band characteristics and CPW compatibility, the selected topology is the ...
Citation Formats
U. Aykutlu, “5th order sigma delta MEMS accelerometer system with enhanced linearity,” M.S. - Master of Science, Middle East Technical University, 2015.