High precision small size I/F converter

The switching circuit of the I/F converter was designed using the discrete devices in order to reduce the stability time of the converter. A simple logic control was designed to make the feedback time of the reference current invariable, with which the error of converter was reduced. The logic control circuit, shaping circuit and drive circuit was replaced by a piece of CPLD circuit, so that the converter's size was reduced. The converter designed using the new method provides an accuracy better than 0.005% with stability time less than 10s, and the size of which is half the normal converter.