Design And Research Of Capacitive Acceleration Sensor Detection Circuit

MEMS accelerometer is an inertial device which is capable of measuring acceleration. The accelerometer can be divided into piezoelectric, piezoresistive, capacitive. Capacitive accelerometer has the characteristics of low temperature drift, high sensitivity, good stability, which is widely used in aerospace, consumer electronics, automotive safety field.In this thesis, the main task is to design capacitive accelerometer detection circuit.The first chapter is a brief overview of the development of MEMS and acceleration sensor classification.The second chapter is discussing the capacitive accelerometer works and detection principle, which provide a theoretical basis for the design of the interface circuit.In the third chapter, firstly, the overall design of the detection circuit, including pre-amplifier, band-pass filter, demodulator, low-pass filter. Pre-amplifier using a single-carrier dual integral circuit, Bandpass filter using two order bandpass positive feedback filter, frequency is40KHz, bandwidth1.5KHz, gain is18.2, achieved on the attenuation and suppress the clutter signal. Demodulation using multiplier phase-sensitive detection circuit. Multiple feedback low-pass filter with low pass filter, frequency is1.59KHz, a gain of10.The fourth chapter is the simulation of each block and system simulation. Preamplifier, by changing the feedback capacitance, the difference is greater than or equal to the capacitance values in the input, can meet the design requirements. The measurement accuracy is of the order of10-I6F. Bandpass filter, simulation results show that frequency is38.9KHz, gain is17.2. Multiplier detector to achieve the required output signal frequency is two times of the input. The characteristic frequency of the low-pass filter is1.59KHz, when frequency is lOHz, the gain of10. When frequency is120Hz began to decay, the40KHz attenuation of-38dB. Deviation analysis of the system, found that the deviation is10%.