High Accuracy Sigma-Delta Modulator implementations via Suboptimal Quasi-Sliding Mode Control

Two novel Sigma-Delta modulator algorithms based on discretized suboptimal second order sliding mode concepts for high resolution analog-to-digital conversion purposes are proposed. Let f
_s
be the finite over-sampling frequency of the modulator, novel schemes that convert to a 1-bit signal, resp., the first, or the second time-derivative of the signal to be modulated are suggested to reduce the error of the conversion process, at the demodulation side, to an O(1/f
_s
²
), instead of O(1/f
_s
^0.5
) of the traditional scheme. The algorithms are discussed and analyzed in the discrete-time setting, and a comparative analysis illustrates the effectiveness of these solutions.