Guigues F., Rudolff F., Kussener E.*L2MP UMR 6137 CNRS - ISEN-Toulon, FR*

Keywords: analog design methodology, EKV MOS model, moderate, MOS sizing, strong-inversion, ultra-low-power, weak

When strong constraints of supply voltage (< 1V ) and bias current (< 100nA) are required, the only way to meet design’s

specifications without using huge silicon area consists on decreasing transistor’s inversion level and therefore going in moderate

inversion. Gm/Id methodology is a good solution in case of dynamic target, but unusable for static circuits. In this case, analog

designers need continuous over inversion level, hand calculation usable equations.

EKV 2.0 MOS model proposes current drain formula continuous from weak to strong inversion. This equation is invertible

and thus usable for hand calculation, but only when transistors are saturated. The solution proposed to have a conduction drain

current expression, continuous from weak to strong inversion and invertible, is to fix a conduction level .

Starting from proposed equations, or standard asymptotes when strong constraint of weak/strong inversion are imposed,

design’s equations can be found. On the other hand, design’s specifications such as acceptable transistors’ sizes or current

bias, permit to fix vectors of solutions for each design’s unknowns. Integration of these vectors and designs’ equations into a

mathematical computing software result in the creation of wholes of solutions which describe completely the design.

It is thus possible to made a complete study of a static circuit, independent of inversion level so as to make optimum

design. Supply voltage and silicium area can be unambiguously optimize, without risk of running in circle as in ”traditional”

approaches. Furthermore, it permits to use circuit simulator only for ”final polish”. As a consequence, the study made, changing

of technology can be made almost immediately.

Journal: TechConnect Briefs

Volume: 3, Technical Proceedings of the 2006 NSTI Nanotechnology Conference and Trade Show, Volume 3

Published: May 7, 2006

Pages: 864 - 867

Industry sector: Sensors, MEMS, Electronics

Topic: Compact Modeling

ISBN: 0-9767985-8-1