A Vector Pair Based DWA Algorithm for Linearity Enhancement of CDACs in the NS-SAR ADC

The conventional DWA algorithm is not direct to be used for the mismatch shaping of the SAR-type DACs that are widely used in NS-SAR ADCs. The emerging DWA algorithm requires an extra coarse ADC which complicates the system and thus limits the figure of merit of the high-resolution NS-SAR ADC. This paper presents vector pair based DWA algorithm omitting the necessity of the coarse ADC. Employing two vectors that initiate at adjacent positions and respectively update to circularly select the elements in a reversed direction, then the mismatch error of the SAR-type DAC is first-order shaped. Not only the theoretical proof is given but also the shaping performance is simulated in this paper.