Procedural capacitor placement in differential charge-scaling converters by nonlinearity analysis

摘要

This paper presents a new approach to capacitor placement in differential charge-scaling data converters. Good capacitor matching is crucial for charge-scaling converter resolution. Differential circuits are preferred to single-ended architectures due to improved immunity to noise and variations. The proposed method is based on the analysis of converter static nonlinearity equations. The impact of capacitor variations on converter linearity is minimized by exploiting spatial correlation between devices. Mathematical analysis is completed for two differential analog-to-digital converters. A procedure to obtain a capacitor placement is presented for each circuit. The architectures are compared with respect to linearity and capacitor placement area.