High resolution digital-to-analog converter

摘要

An apparatus and method for expanding the resolution of digital-to-analog converters is described. Two limited resolution digital-to-analog converters are cascaded in such a manner that one converts the low order bits of digital input signal and the other converts the higher order bits. The output of the higher order digital-to-analog converter is applied directly to a summing circuit while the output of the low order digital-to-analog is first passed through an attenuator. When the low order digital-to-analog converter receives all logical ones, a carry is performed to the higher order digital-to-analog converter. The low order analog-to-digital converter is then reset by a successive approximation technique. Operation is essentially the same for borrow operation.