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A multibit digital-analog (D/A) differentiator is used in the forward correction path of a dual-truncation delta-sigma (DeltaSigma) D/A converter (DAC) to obtain the desired second-order noise-shaping function for converting mismatch-induced in-band quantization noise to out-of-band frequencies. The multibit D/A differentiator can be configured by embedding binary-weighted current-steering DAC elements into digital differentiators without concern of linearity. In simulations, the newly proposed DeltaSigma DAC is 20 dB more effective in noise reduction than widely adopted first-order noise-shaping methods under the identical mismatch conditions of DAC elements (2% in average global mismatch and 0.3% in adjacent element mismatch). This method also offers advantages of compact circuit implementation with smaller routing area and less power consumption over those of thermometer-coded or digital signal processing based counterparts with the same second-order mismatch shaping.
Circuits and Systems II: Express Briefs, IEEE Transactions on (Volume:55 , Issue: 1 )
Date of Publication: Jan. 2008