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From: williams@kirk.DEC (John Williams 223-3402)
Newsgroups: net.analog
Subject: The difference between capacitors and batteries
Message-ID: <158@decwrl.UUCP>
Date: Thu, 6-Dec-84 11:29:12 EST
Article-I.D.: decwrl.158
Posted: Thu Dec  6 11:29:12 1984
Date-Received: Sun, 9-Dec-84 03:24:23 EST
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	A battery is an extremely nonlinear capacitor. This is due to
the fact that the charge changes the characteristics of the dielectric.
Period. They optimize difference aspects of similar phenomenon. You will
find that all capacitors are somewhat nonlinear. Vendors tend to stuff
this characteristic into the absolute tolerance. Polystyrene and 
polypropalene ( spelling? ) tend to be the most linear. Batteries are
the most nonlinear. You don't find many that are inbetween until you
get to solid state capacitors processed in silicon, where the depletion
layer varies with charge. The development of linear capacitors in IC's
was a major breakthrough for systolic arrays and switched capacitor
networks. It should be noted the the nonlinearity in silicon is inverse
to the nonlinearity you find in batteries.

					----{ john williams }----