DESIGN OF SYSTEM ON A CHIP This page intentionally left blank Design of System on a Chip Devices & Components Edited by Ricardo Reis Universidade Federal Rio Grande Sul, Brasil and Jochen A.G Jess Eindhoven University of Technology, The Netherlands KLUWER ACADEMIC PUBLISHERS NEW YORK, BOSTON, DORDRECHT, LONDON, MOSCOW eBook ISBN: Print ISBN: 1-4020-7929-X 1-4020-7928-1 ©2004 Kluwer Academic Publishers New York, Boston, Dordrecht, London, Moscow Print ©2004 Kluwer Academic Publishers Dordrecht All rights reserved No part of this eBook may be reproduced or transmitted in any form or by any means, electronic, mechanical, recording, or otherwise, without written consent from the Publisher Created in the United States of America Visit Kluwer Online at: and Kluwer's eBookstore at: http://kluweronline.com http://ebooks.kluweronline.com Contents Designs of System on a Chip Introduction R Reis; J A G Jess BJT Modeling with VBIC C.C McAndrew 19 A MOS Transistor Model for Mixed Analog-digital Circuit Design and Simulation 49 M Bucher; C Lallement; F Krummenacher, C Enz Efficient Statistical Modeling for Circuit Simulation C.C McAndrew 97 Retargetable Application-driven Analog-digital Block Design J E Franca 123 Robust Low Voltage Power Analog VLSI Design T B Tarim; C.H Lin; M Ismail 143 Ultralow-Voltage Memory Circuits K Itoh 189 Low-Voltage Low-Power High-Speed I/O Buffers R Leung 233 Microelectronics Toward 2010 T Yanagawa, S Bampi, G Wirth 245 Index of Authors 265 Chapter Design of Systems on a Chip: Introduction 1 Ricardo Reis; 2Jochen A G Jess Prof at the Informatics Institute UFRGS – Federal Univ of Rio Grande Sul; P.O Box 15064 – 91501-970 Porto Alegre, BRAZIL Tel: +55-51-316-6830, Fax: +55-51-3316-7308; E-mail: reis@inf.ufrgs.br Eindhoven University of Technology, p.o.box 513, 5600 MB Eidhoven, The Netherlands, Phone: 31-40-247-3353, Fax 31-40-246-4527 Key words: VLSI, microelectronics, roadmap, SoC Abstract: A short review of integrated circuit history is presented with a view in the effects of this revolution on the way of life It goes on to say that Moore's law triggers a technology shockwave To curb the entrepreneural risks the professional industry associations decided to anticipate the technology evolution by setting up roadmaps The ITRS semiconductor roadmap was complemented by other roadmaps that preview the technology shockwave originating from the chip technology and propelling the product technology The book content's focus is on devices and components for the design of systems on a chip This chapter also presents an overview of the book contents MOORE’S LAW AND THE CONSEQUENCES In 1947 John Bardeen, Walter Brattain and William Shockley invented the transistor Except for perhaps a few experts the event went largely unnoticed So had been the design of the world’s first stored program computer, Konrad Zuse’s Z3, completed in 1941 Nobody, not even the German military, was aware of the significance of this invention At the same time, in Bletchley Park, in the UK, a team of dedicated people inspiringly guided by Alan Turing designed the “bomb” The bomb was a Chapter mechanical computing device, based on the ideas of the Polish mathematician Marjan Rejewski Turing’s version of it was able to break the code generated by the “Enigma” machine used by the German Navy So the British Navy was able to decipher the messages of the German Navy, which controlled the movements of the German submarine fleet in the Atlantic Therefore the allies succeeded to maneuver sufficient supplies across the Atlantic so as to prepare the invasion in Normandy, which essentially decided World War II in Europe This fact remained largely unrecognized for almost three decades after the end of the war All cryptographic activity was kept secret because of the Cold War situation emerging shortly after WW II was ended The bomb that brought scientific news on the public agenda was the nuclear bomb, the first of which was put to action on August 5, 1945 From that moment on scientific results became hot news items But most people were interested in nuclear science exclusively because of the public perception that nuclear power would decide the next hot war Only experts recognized the military potential of telecommunication and computers Less than ten years after the invention of the transistor computers were built using them as essential switching elements Jack Kilby from Texas Instruments created the first integrated circuit in 1958 Robert Noyce and Gordon Moore would establish companies like Fairchild and Intel Another 13 years after the invention of the integrated circuit the first microprocessor, the Intel 4004, entered the market, carrying 2300 transistors on a single chip 00 95 20 90 19 85 19 80 19 75 19 70 19 65 19 19 60 #trans/die 19 19 55 100000000 10000000 1000000 100000 10000 1000 100 10 Figure Moore's Law Microelectronics toward 2010 251 MOS transistor – The transistor size, especially the channel length, has been following the course of shrinkage in order for both increasing the integration level and reducing the switching energy per logic transition, which is the product of switching delay and power dissipation This tendency is plotted in Figure However the functions of transistor as an active device are disturbed by the following phenomena when the shrinkage progresses: – The short channel effect reduces the threshold voltage and increases the off-state leakage current Furthermore, there is a lower limit on channel length, because too thin depletion regions are subject to quantum mechanical tunneling of charge carriers from source to drain, leading to high leakage currents – Enough area for heat removal through substrate cannot be secured This is a problem for any densely packed integrated circuit, and will limit the device density, since overheating can cause malfunction – Variations of transistor characteristics due to fluctuations of process parameters become relatively large, and the lowering of supply voltages, mandatory to face the imperative reduction of CMOS power dissipation, makes the circuits more sensitive to these fluctuations Many of these fluctuations arise from processes that are stochastic in nature and can not be improved by lithography, like ion implantation For a doping concentration NA = 5x1018 cm–3 there will be less than 50 dopants in the channel region of a transistor with W=L=50 nm The actual number of dopants found in the channel follows a normal distribution This leads to significant scattering in threshold voltage and drive current (Asenov, 1998) Even if the number of dopants in the channel could be precisely controlled, there would still be electrical parameter variations due to the microscopic arrangement of the dopants To solve the problem, alternatives to ion implantation are necessary to position individual dopant atoms in specific lattice sites – The leakage current through the gate oxide increases exponentially as oxide thickness decreases Quantum mechanical tunneling currents exclude the use of SiO2 for layers below nm, needed for devices with L