关键词: 数模转换器, 微分非线性, 积分非线性, 最小二乘法, 特征点

Abstract: The test of high precision digital-to-analog converter (DAC) is always the difficulty of mixed signal test. Linearity is an important indicator of DAC static error,includingtwo parameters: integral nonlinear (INL) error and differential nonlinear (DNL) error.Aiming at the problem of how to test the linearity of highprecision DAC efficiently and accurately, the least square method is used to convert the curve fitting algorithm to calculate the linearity.At the same time,based on the internal structure of current mode DAC, an optimization method using characteristic points to test the linearity of DAC is proposed.The V93000 automatic test equipment is used to verify the 16 bit DAC. The INL test result is －1.88 LSB, the DNL test result is 1.202 LSB before optimization , the INL test result is －1.24 LSB, and the DNL test result is 0.594 LSB after optimization.The results show that the test results of linearity can be effectively improved by using the characteristic points combined with the least square method to fit the conversion curve algorithm. At the same time, the test time is reduced from 7 s to 1 s. The test error caused by the temperature drift of the test resistance for a long time is avoided, and the test efficiency and precision are improved.

Key words: digital-to-analog converter, differential nonlinear, integral nonlinear, leastsquare method, feature point