Ratio independent cyclic A/D and D/A conversion using a recirculating reference approach

In this paper, a new method is described which uses switched capacitor techniques to implement cyclic A/D and D/A converters. By periodically modifying the reference voltage to compensate for the nonideal signal transfer loop gain, it is possible in principle to build analog-digital (A/D) and digital-analog (D/A) converters whose linearity is independent of component ratios and which occupy only a small die area. These converters require two moderate-gain MOS operational amplifiers, one comparator, and a few capacitors.