Performance limits of mixed analog/digital circuits with scaled MOSFETs

Constant electric field (CE), quasi-constant voltage (QCV), and constant voltage (CV) scaling laws are used as guides to MOSFET miniaturization. It is found that: 1) the QCV scaling law gives the best performance of the three scaling laws; 2) improvements in unity-gain bandwidth with scaling are less than predicted by the first-order theory due to mobility degradation; 3) gate length can be scaled down to 0.25 mu m while maintaining 10-bit accuracy for analog circuits (threshold variation limit); and 4) when gate lengths deviate from designed values, noise immunity for digital circuits is degraded mainly due to degradation in the saturation characteristics (drain-induced barrier lowering).<
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