Analysis on Capacitor Mismatch and Parasitic Capacitors Effect of Improved Segmented-Capacitor Array in SAR ADC

This paper presents an analysis on capacitor mismatch and parasitic capacitors effect of the improved segmented-capacitor array to alleviate the limitation of mismatching performance and avoid a non-binary-weighted coupling capacitor. Both the matching of binary-weighted capacitor network and parasitic capacitors on both sides of the coupling capacitor have great influence on the resolution of ADC system. The relationship among the mismatching of binary-weighted-capacitor network and the parasitic capacitors and the attainable resolution of ADC is analyzed by giving precise theoretical demonstration. Therefore, a theoretical basis is provided for designers to choose process, layout, circuit structure, and capacitor size in their design of SAR ADC.