Practical Aspects of CMOS Layout

Flemming Stassen
Department of Information Technology
Building 322
Technical University of Denmark

Preface

These notes on the practical aspects of layout have been assembled for use in a lecture course, `49260 Design of Integrated Circuits 1', given at the Department of Information Technology, Technical University of Denmark. The notes assume an understanding of integrated circuit design corresponding to Part 1 of `Principles of CMOS VLSI Design: A Systems Perspective (2nd. ed. 1993), Neil H. E. Weste & Kamran Eshraghian'[WE92], the textbook used in the lecture course, and the notes serve as an addendum to the textbook.

The topics covered in these notes are practical aspects and limitations of layout, when random process variations result in electrical parameters, which are not constant but rather statistically distributed. The focus is on design methods for reducing or eliminating the effects. In this relation, the notes serve three purposes:

• to introduce layout structures robust to process variations,
• to present simplistic models for analog building blocks with the aim of analysing consequences of parameter variations,
• to present the basic noise considerations which guide the layout of supply structures etc.

It was the intention of the author to put together a text that may serve both as an introduction for a newcomer and as a work of reference for the design engineer.