The data converters ? analog-to-digital and digital-to-analog converters (ADC?s and DAC?s respectively) ? provide an important interface function between analog and digital circuits in most electronic systems. As MOS integrated circuit technologies began to replace bipolar technologies in the 1960s and 1970s, it became realistic to integrate both complicated digital and high performance analog circuits on a single silicon die. Therefore, there emerged a strong need for MOS data converters. The most popular data converter architecture for bipolar integrated circuits was an R-2R ladder and its variants. However, the lack of precision resistors and low transconductance in MOS transistors made the R-2R ladder difficult to provide comparable accuracy in MOS technologies.