Multibit Sigma - Delta A/D converter incorporating a novel class of dynamic element matching techniques

摘要

A dynamic element matching technique is applied to multibit sigma-delta modulators. The approach translates the harmonic distortion components of a nonideal digital-to-analog converter (DAC) in the feedback loop of a sigma-delta modulator to high-frequency components, which can then be filtered out by the decimation filter. Computer simulations have confirmed that with this approach a third-order sigma-delta modulator employing a 3-bit forward ADC, a 3-bit feedback DAC with a random mismatch of 0.1% can achieve a 104-dB (17+bit) dynamic range and a harmonic distortion below 100 dB, with an oversampling ratio of 64. The technique does not generate any tone in the passband.