Linearity enhancement of multibit delta-sigma A/D and D/A converters using data weighted averaging

Abstract

A dynamic element matching algorithm, data weighted averaging, is introduced for use in multi-bit \\Delta\\Sigma data converters. Using this algorithm, distortion spectra from DAC linearity errors are shaped by first-order noise shaping, resulting in a dynamic range improvement of 9 dB/octave when DAC errors dominate. Combining this technique with random dithering eliminates the aliasing of the DAC errors into baseband. Simulations show that with only 1% element matching 110 dB signal-to-noise ratio (18 bits) is achieved for a third-order 3-bit modulator with an oversampling ratio of 128. 1 Introduction Oversampling \\Delta\\Sigma data converters have displaced traditional converter architectures in audio and instrumentation applications where low frequency, high-resolution and high linearity conversion is required [1]. The high resolution obtained from these converters is attributed to the inherent linearity of a single-bit quantizer in the \\Delta\\Sigma modulator. This high linearity mak...