This paper presents the performance of recently developed MEMS capacitive tilt sensor. The capacitive sensor, which can be considered as a static accelerometer, is fabricated using bulk micromachining technique on a 100-mum-thick z-cut quartz wafer. High-sensitivity and low-noise are achieved with stable output performance in the range of plusmn1deg. The performance evaluation was performed at the 0.625 V excitation voltage and 9.1 Hz data update rate. The typical sensitivity with good linearity is 403.5 fF/deg, which corresponds to 23.1 pF/g and the typical RMS noise is 74 aF, which corresponds to 25 aF/radic(Hz) (0.9 mug/radic(Hz)) noise floor. High-precision measurement of 0.001deg has been demonstrated.
[Show abstract][Hide abstract] ABSTRACT: Multi-hop relaying has attracted considerable attention recently as a key technique for improving cell coverage and throughput in wireless communication. We modelled various ARQ mechanisms that have been proposed for wireless multi-hop relay systems based on a Discrete Time Markov Chain(DTMC) technique. We analyzed the performance of the ARQ mechanisms with respect to delay and throughput. We also validated the proposed ARQ model and the performance analysis by comparing the analysis with simulation results.
Proceedings of the 67th IEEE Vehicular Technology Conference, VTC Spring 2008, 11-14 May 2008, Singapore; 01/2008
[Show abstract][Hide abstract] ABSTRACT: This study employs the low temperature UV-glue dispensing and curing processes to bond a bulk block on a suspended CMOS MEMS stage to increase the proof-mass of tilt sensor. Thus, the sensitivity and resolution of CMOS MEMS capacitive-type tilt sensor are significantly improved. Such simple post-CMOS process inherits from the mature technology for packaging. In application, this study successfully demonstrates the bonding of a bulk solder ball with a tilt sensor fabricated using the standard TSMC 0.35μm 2P4M CMOS process. Measurements show the sensitivity is increased for 3.4-fold, and the resolution is improved from 1º to 0.1º, after adding the solder ball. Note that the sensitivity can be further improved by reducing the parasitic capacitance and the mismatch of sensing fingers caused by solder ball.
[Show abstract][Hide abstract] ABSTRACT: This paper reports a micro-electro-mechanical tilt sensor based on resonant sensing principles. The tilt sensor measures orientation by sensing the component of gravitational acceleration along a specified input axis. Design aspects of the tilt sensor are first introduced and a design trade-off between sensitivity, resolution and robustness is addressed. A prototype sensor is microfabricated in a foundry process. The sensor is characterized to validate predictive analytical and FEA models of performance. The prototype is tested over tilt angles ranging over ±90 degrees and the linearity of the sensor is found to be better than 1.4% over the tilt angle range of ±20°. The noise-limited resolution of the sensor is found to be approximately 0.00026 degrees for an integration time of 0.6 seconds.
Frequency Control Symposium (FCS), 2012 IEEE International; 01/2012
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