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Abstract:In this article, we present a simple MEMS magnetic sensor based on Lorentz Force principle. In this work, the sensor is designed, fabricated and characterized capacitively using a standard capacitance to voltage MS3110 circuit. The sensor is fabricated based on double thickness Poly-MUMP surface micromachining process. In this process, the two Poly layers are combined to increase the thickness of the sensor beams and central shuttle. In response to an input excitation current an out of plane motion due to Lorentz force occurs which is detected by the change in capacitance between the moving and static plate. The experimentally detected resonant frequency of the sensor is 5.1 kHz. The experimental sensitivity achieved by the sensor at atmospheric condition is 5.59 V/T for the input current of 30 mA with a damping ratio of 0.010.

In this paper, a chopper stabilized fully differential CMOS pre-amplifier circuit is presented. The proposed circuit is designed for sub-atto Farad capacitive CMOS MEMS sensing applications. Chopper stabilization technique is employed to minimize flicker (1/f) noise and offsets in the circuit. The proposed circuit is designed using MIMOS 0.35 μm AMS CMOS 3.3 V technology and simulation results from Cadence Virtuoso Spectre circuit simulator show that the proposed circuit is able to detect capacitance changes ranging from 0.0375 aF to 37.5 fF, attain an input inferred noise of 0.9 nV/√Hz, gain of 18.1 dB at 3-dB frequency of 5.5 MHz with total power consumption of 0.33 mW.

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