The Designer’s Guide Community downloaded from www.designers-guide.org Modeling Dielectric Absorption in Capacitors

Version 2c, 3 October 2004 It is well known that dielectric absorption plays a critical role in determining the accuracy of analog sampled-data systems that are based on charge storage, such as sampleand-holds and switched-capacitor ADCs. Less appreciated, but no less important, is the role it plays in determining the quality factor, or Q, of the capacitor. Dielectric absorption has both storage and loss components that act, and are significant, over the entire usable frequency range of the capacitor. Along with background information on the origins of dielectric absorption, this paper presents two models for a capacitor that exhibits dielectric absorption. The first is the relatively well known model proposed by Dow. The second is a model with relatively little exposure that is based on the dielectric permittivity model of Cole and Cole. This model has fewer parameters than the Dow model and is predictive over a very broad range of frequencies