Delta–Sigma D/A Converter Using Binary- Weighted Digital-to-Analog Differentiator for Second-Order Mismatch Shaping

摘要

A multibit digital–analog (D/A) differentiator is used in the forward correction path of a dual-truncation delta–sigma ( $Delta Sigma$) 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 $Delta Sigma$ 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.