The Functional Circuit Design Of Small-Sized 6 (1/2) Digit Digital Multimeter

DMM is a fundamental kind of instrument for measurement.It is widely used in daily life,industrial production,testing and national defense.Its relative low price,high precision,special application are main features of its development.As the requirement proposed by 41th research institution belonging to CETC,we start to develop a type of 6 (1/2) digit DMM with high precision,small-sized and anti-interference.This paper emphasize on the circuit design of this kind of DMM.In the text,we aim at the design of circuit,ensure the reduction of its size.The related technical index can take the Agilent 6.5 bits DMM as reference.Research in reducing the circuit size of DMM and its consumption lead us to discuss how to design the whole scheme.We proceed the hardware circuit design,software circuit design and the calibration and testing of circuit.The concrete contents are as follows.1.The hardware circuit design of DMM.We adopt highly integrated proportion resistance to reduce influence to measurement precision caused by temperature excursion,adopt integrated chip to substitute discrete component,simplify circuit and decrease the use of components.And we adopt software revision to substitute compensation circuit to simplify the whole circuit while concerning the measurement of AC signal.2.In the lower computer,we design the program of measurement and calibration.We adopt LabVIEW to finish the panel design of the higher computer,then we use the panel to complete debugging work.3.Analysis the error source of DMM,chose the calibration model.To improve the measurement precision of DMM,we adopt a method of figure average for the reason that it can reduce measurement error.4.Based on the requirement proposed by the national defense project of the whole system,we are able to gain the testing results and demonstrate the feasibility and reliability of the design.