Research And Development Of Measurement Circuit For The Piezoelectric Accelerometer

The measurement circuit for the piezoelectric accelerometer is the key component in the measurement and control of non-electric physical quantity, especially in the application of vibration and strike measurement. Piezoelectric accelerometer can be regarded as the component that can produce electric charge with high impedance, but the quantity of electric charge is very subtle. Taken this reason into account, the general measurement circuit does not work well. Therefore, a special measurement circuit suitable for the piezoelectric accelerometer is used instead.Nowadays, the charge amplifier, whose output (voltage) is in proportional to the input(charge), is employed as the most popular measurement circuit for piezoelectric accelerometer. One of its notable characteristics is the sensitivity of the sensor has nothing to do with the length of the cable, so the cable can reach several kilometers. Through further research on the measurement circuit for the piezoelectric accelerometer, a new kind of charge amplifier is introduced in the paper, which uses integrated circuit to replace a large number of discrete components. It contains six parts, including charge converting circuit, condition magnifying circuit, high and low pass filter, output amplifier, overload indicator circuit and stabilized voltage supply circuit. Compared with the standard charge amplifier, the feasibility and reliability of the system are confirmed. The discussion covers:1,By theoretical analysis on the measurement circuit of the piezoelectric accelerometer, a optimization design for charge amplifier is proposed which uses TL081 to replace a large'number of discrete components. The design not only improve the integration of the circuit, but also have some extra merits, including smaller volume, lower consumption, less autoeciousness and stronger resistance to interruption.2,Affiliated conditional circuit and filter to the devised charge amplifier, the signal is normalized and the noise ( generally, high frequency signal and DC signal) are restrained. As a result, the output of the waveform is improved, as well as the testing precision.3,The circuit board of the charge amplifier is designed, then the contrasting experiments is made. The result shows that the design is reasonable and convenient, and all the data conforms to the requirement.4,Through the error analysis of the charge amplifier, the plan of the succeedingresearch is put forward.This paper provides a general idea for the development of measurement system for the piezoelectric accelerometer. The design method of this system is of great significance for designing similar systems.