The Design Of Low Temperature Drift On DMM Measurement Circuit Technology

Digital multimeter is a kind of basic measuring instrument, in industrial production and daily life. DMM is widely used in national defense testing, measurement and other fields. At this stage, the main direction of the development of DMM is the high precision, the low price and the special application. According to the requirements of A Research Institute, we carried out 61/2 digital multimeter circuit research with low temperature drift, strong antiinterference and high precision.In this paper, digital multimeter circuit are designed, in order to reduce the temperature drift and to ensure measurement accuracy. According to the technical index of A Research Institute, the method to reduce the temperature drift coefficient is focused researched, by reference to the domestic and foreign most widely used 61/2 digital multimeter(Agilent 34401A). Digital multimeter overall design scheme is discussed in detail. Including the hardware circuit designing, low temperature drift designing, software designing, circuit calibration and testing.This design is based on the circuit measurement accuracy, to measurement resistance, frequency, AC current, DC current, AC voltage and DC voltage. At the same time, the circuit topology structure of desktop 61/2 digital multimeter is adopted, in order to research and design of low temperature drift coefficient, including the standard of low temperature drift, the low temperature drift operational amplifier, the temperature resistance matching, the improved of low temperature drift with built-in temperature sensor and the error analysis. In the PC, using the soft panel of Lab VIEW software to debug programs. To improve the measurement accuracy, this paper makes a detailed analysis of the DMM error sources and the calibration model. And the numerical average for the measurement data is calculated. Using the above design to test circuit, the result shows that the technique and method used in this paper can meet technical requirements.It’s helpful to improve the measuring accuracy of the 61/2 digital multimeter, though reducing the digital multimeter temperature drift coefficient of the system. It’s useful to reduce the front-end noise of the 61/2 digital multimeter. This paper has important significance for the promotion of the 61/2 digital multimeter in engineering and practical application.