20位脉宽调制直流电压D/A转换器设计

Design of 20 bit pulse width modulate digital-to-analog converter

本文设计了一种高精度脉宽调制D/A转换器,该方案采用双路脉宽调制电路,并进行比例叠加来实现20位的D/A转换,主要用于产生0～10 V可调直流电压基准信号,最小分辨率达到1×10^(-7)。该文首先确定了双通道叠加原理的设计方案,对脉宽调制技术的实现进行了详细地阐述,并给出了具体的设计方案。该设计方案已经成功应用于100 A直流电流标准的设计中,对高精度标准研制过程中基准电压发生电路的设计具有指导意义。

The design of a high accuracy digital to analog （D/A） conversion by the method of pulse＇s width modulate, which adopts double ways pulse＇s width modulate and proportion divider in order to achieve the 20 bit D/A, is presented in this paper. The 20 bit D/A is realized to provide 0-10 V direct voltage, and the resolution ratio reaches 1×10^-7. In the paper, the design of principle for double ways pulse＇s width modulate is analyzed, the technique to realize the pulses width modulate is described in detail, and the principal circuits are given. The design has been already successfully applied in the 100 A direct current standard, and it also has some leading meaning to the reference electric voltage in research and manufacturing process for high-accuracy standard.