Digital compensation of DAC mismatches in multibit delta-sigma ADCs
A digital compensation technique to overcome the effects of the digital-to-analogue converter (DAC)'s mismatches in multibit delta-sigma modulators is described. The technique is purely digital, does not require the injection of a pilot signal and is compatible with binary-weighted element DACs. Simulation results confirm the validity of the compensation technique for a four-bit, fifth-order lowpass modulator with an oversampling ratio of 12 and 1 mismatch in the DAC elements. The compensated modulator exhibits a peak signal-to-noise-and-distortion ratio of 74.5 dB; that is within 0.5 dB of the ideal system without mismatch.