Study On Improving The Accuracy Of Analog Measurement Circuit

This thesis studied the methods for improving the accuracy of analog measurment circuit.Methods for reducing the system noise and temperature drift, improving the stability of system were proposed to realize the growth of accuracy. Firstly, according to the methods of improving accuracy which were used at home and abroad as well as the laboratory, sevearl methods for further accuracy improvement were proposed.The thesis studied the evaluation methods of several key indicators of measurement circuit, such as system noise, stability, temperature coefficient, error bounds and linearity, provided the basis for evaluating the methods of accuracy improvment.Then we introduced several platforms of experimentation, including the current measurement circuit, the digital multimeter auto-measurment system based on GPIB-USB interface, the data acquiction system based on USB interface. These platforms provided conditions for experiments.Chapter four analyzed different methods of accuracy improvment and demonstrated them by experiments, including the design improvment of circuit, multi-channel fusion, self-calibrating and electrical aging. These methods reduced the system noise and improved the stability of measurment circuit.In addition, a method of of improveing accuracy by selecting components through testing parameters of components was proposed in this thesis. This method was indroduced in Chapter five. Chapter five Analyzed the influence, of three main component used in analog measurement circuit, to system noise and temperature characteristics. Developed component selection circuit to pick up component which has low noise and temperature coefficient.Experimental results showed that this method can improve the accuracy of measurement circuit by effectively damping the system noise and tempearture cofficient.According to the methods of accuracy improvment proposed in this thesis, Chapter six designed a new analog measurment circuit and tested it. Some shortcomings and expectations for further research were given in Chapter seven.