High-speed, high-resolution voltage output digital-to-analog converter and method

摘要

A string DAC having 2^M string resistors includes a plurality of switches for selectively coupling, according to the decoding of an M-bit MSB subword, the voltage across a string resistor to an interpolation sub-DAC which interpolates it according to the decoding of an N-bit mid-subword. The voltage across the string resistor is multiplexed, according to the decoding of an N-bit mid-subword, to various inputs of 2^N differential transistor pairs of an interpolation amplifier. A P-bit delta sigma modulator produces a delta sigma modulated signal, according to a P-bit LSB subword, to control multiplexing of voltages on the terminals of the string resistor to an input of one of the differential transistor pairs selected by decoding of the N-bit mid-subword to monotonically average a contribution of the selected differential transistor pair to generation of an output voltage representing a word including the M-bit, N-bit, and P-bit subwords.