A 110 dB THD, 18 mW DAC using output sampling and feedback to reduce distortion

Abstract

A digital-to-analog converter (DAC) with -110 dB total harmonic distortion (THD) is required to generate signals for linearity tests of data acquisition channels and sensors. Low power and a minimal number of external components are important to the application. A 256 kHz noise shaped bit stream is provided with a maximum signal frequency of 100 Hz. The out-of-band quantization noise has to be attenuated to less than -50 dB. A topology that minimized the number of critical circuit blocks in the DAC is preferable to minimize the design tasks and risks.