Noise Measurement in Microsensor Applications

In this research, spectral coherence noise measurement technique is used to measure noise of capacitive accelerometers, based on measuring the spectral coherence and outputs of two identical sensors exposed to the same input stimulus. This effective technique can be applied to any sensor characterization problem where there is interest in distinguishing instrumental noise from background noise. The simulation study has been done in MATLAB to verify the proposed method reliability to calculate contributions of different noise sources in a system. To verify effectiveness and accuracy of the proposed technique in practical systems, we continue our research in experimental work, using this method on a commercial accelerometer. Then, the technique is applied to measure noise of microsensor systems which consist of MEMS capacitive accelerometer followed by low-noise interface electronics. The proposed technique is also used to measure and quantify the noise contribution of different stages of interface electronics. Experimental results are compared to either reported data on the used devices datasheet, analytical equations, or simulation results. The similarity between experimental results with theoretical values and simulation results verifies the measured noise for microsensor systems. Thanks to spectral coherence noise measurement technique, we will be able to characterize noise behavior of fabricated sensors and reader boards, and determine the lowest noise sensor and interface electronics.