一种提高分段式DAC线性度测试效率的方法

A Method to Improve the Linearity Measurement Efficiency of the Segmented DAC

随着数模转化器（DAC）位数的增加,模拟量的步进值越来越小,数字万用表的精度和负载电阻的热效应成为影响DAC线性度测量的重要因素。基于分段式电流舵DAC的结构,结合其二进制和温度计译码电路的特点,从理论上提出了一种使用简码测试线性度的方法,并以一款分段式10 bit DAC为例,分别采用简码和传统的全码方法验证了它的微分非线性DNL与积分非线性INL。结果表明,简码测试和全码测试得到的DNL与INL曲线趋势一致,但简码测试效率高,仅占全码测试周期的1/8;另外简码测试减小了负载电阻温漂引入的误差,因此相比全码测试线性度的性能提高了0.1-0.2 LSB。

With the increase of bits in the digital-to-analog converter（ DAC）,the analog step is much smaller,the precision of the digital multimeter and load thermal effect in resistance become important factors in the linearity measurement of the DAC. Based on the structure of the segmented current steering DAC,combined with its characteristics of binary and thermometer decoder circuit,a method using selected codes to evaluate the linearity was proposed. Then a 10 bit DAC with segmented structure was presented,both selected codes and all codes in traditional tests were carried out to verify DNL and INL of it. The test results show that the trends of curves in all codes and selected codes tests are consistent,but selected codes test is efficient and only 1 /8 test cycle compared to the all codes test. The errors induced by load temperature shift are reduced,the performance of the linearity increases by 0. 1-0. 2 LSB than that of all codes test.