Design Of A New Charge Amplifier

In modem industry and automatic production process, piezoelectric accelerometers are usually adopted to acquire vibration and strike signals, and they generally need to connect to charge amplifier for signal enlargement and output. Therefore the charge amplifier is an inevitable secondary instrument which is essential to measuring appliances. But the present charge amplifier remains high price for its complicated circuit design, so the performance price ratio is not very ideal. All these factors seriously influence the widespread use of piezoelectric accelerometer. So it is very necessary to develop a kind of charge amplifier with higher performance cost ratio and more utility.In this thesis, a number of difficulties in the traditional charge amplifier design are analyzed detailedly, and a new charge amplifier is redesigned. The newly designed amplifier uses several high accuracy integrated circuits to replace a large number of discrete components, and realizes charge to voltage conversion. In order to increase the measuring accuracy and restrain interferences effectively, microcontroller is introduced to realize the digital amplifier gain control, and programmable filtering design, which makes the overall performance of the charge amplifier more ideal. The main body of this thesis lies in two parts: analog circuit design and digital intelligent control circuit design. The analog circuit mainly includes charge-voltage conversion circuit, normalized circuit and anti-aliasing filter. The digital intelligent control circuit is based on microcontroller AT89C52, which replaces the traditional panel controls and realizes automatic gain control, automatic switching filtering frequency.The experimental results indicated that the frequency response of the charge amplifier could be as low as 0.03 Hz. The newly designed charge amplifier has several advantages such as simple circuit, convenient adjustment, small size, low power consumption and good anti-jamming performance, which make it become a perfect instrument with high practical value.