A Dynamic Dither Gain Control Technique for Multi-Level Delta-Sigma DACs with Multi-Stage Second Order Dynamic Element Matching


IEICE TRANSACTIONS on Electronics   Vol.E94-C   No.3   pp.346-352
Publication Date: 2011/03/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E94.C.346
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electronic Circuits
dynamic element matching,  dither control,  delta-sigma digital-to-analog converter,  

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A dynamic dither gain control technique for multi-level delta-sigma Digital-to-Analog Converters (DACs) using multi-stage Dynamic Element Matching (DEM) with a second order loop filter is proposed. The proposed technique provides improvement on the mismatch shaping performance through dynamic control of delta-sigma modulator dither gain. A large dither gain, which suppresses DEM operation dependency on input signal, is applied to delta-sigma modulator, when DEM loop filter output is greater than a designed reference. The design example using the proposed technique on a third order 17-level delta-sigma modulator with 3-stage cascaded DEM is shown in this paper. Simulation result with 1% analog segment mismatch shows over 10 dB improvement of THD+N performance under -50 dB amplitude input signal, compared to the case without the proposed technique.