Systems with Digital Integrated Circuits Introduction Sorin Hintea Basis of Electronics Departament
Commutative logic The operation of digital circuits is based on the use of switches capable of going through two distinct states and opposite each other Ideal switches have zero resistance in ON and infinite in OFF state In digital circuits are used, electronic switches made with MOS transistors These transistors are real circuit elements whose ON and OFF resistors are finite Conductive resistance other than 0 will cause the output response to be delayed The finite value resistance in the locked state will result in a final drain current through the blocked switch and therefore undesired power dissipation MOS transistor V G = GND V G = VDD 0 1 Cut-off conduction Systems with digital integrated circuits - Introduction 2
Proiectarea CID nivele de abstractizare Real Circuits Response Logic switches in real digital integrated circuits are built with MOS transistors which have an ON resistance of about10 kohms and OFF resistance of about 100 Mohms. These values are far from the ideal ones and cause power losses and delays of signal propagation through the circuits R v out v in C t p = ln(2) t= 0.69 RC Time behavior of digital circuit s output Systems with digital integrated circuits - Introduction 3
Ideal and real digital circuits Behaviour of real digital circuits 3 2.5 2 V out (V) 1.5 1 t p = 0.69 C L (R eqn +R eqp )/2 0.5 0-0.5 0 0.5 1 1.5 2 2.5 t (sec) x 10-10 Blue - ideal input signal; Black real output signal Time behavior of digital circuit s output Systems with digital integrated circuits - Introduction 4
Ideal and real digital circuits Delay in signals propagation - effect of circuit non idealities V in 50% t V out t phl t plh 90% 50% 10% t t f t r Systems with digital integrated circuits - Introduction 5
Digital Circuits Design First digital integrated circuits 1947 making the first transistor in the Bell Telephone labs 1949 first bipolar transistor by Schockley 1958 first integrated CMOS circuit 1962 first integrated TTL family circuit (Transistor- Transistor Logic) 1972 first 4 bits microprocessor 4004 made by INTEL Systems with digital integrated circuits - Introduction 6
Digital Circuits Design First digital integrated circuits In the 1970s, mostly nmosprocesses were used, cheaper but with high power consumption [Vadasz69] 1969 IEEE. Intel Museum. Reprinted with permission. From the 1980s to today, more and more CMOS processes are being used for their reduced power consumption Systems with digital integrated circuits - Introduction 7
The Moore s law In 1965, Gordon Moore noted that the number of transistors on a chip doubled every 18 to 24 months. So he predicted that semiconductor technology will evolve to double the number of transistors every 18 months, which is still true today LOG 2 OF THE NUMBER OF COMPONENTS PER INTEGRATED FUNCTION 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 Electronics, April 19, 1965. Systems with digital integrated circuits - Introduction 8
The evolution of the number of chip transistors by 2010 Digital Circuits Evolution 1,000,000 K 1 Billion Transistors 100,000 10,000 1,000 100 10 8086 i486 Pentium i386 80286 Pentium III Pentium II Pentium Pro Source: Intel 1 1975 1980 1985 1990 1995 2000 2005 2010 DupaRabaey, 2005 Projected Systems with digital integrated circuits - Introduction 9
The evolution of the number of chip transistors by 2010 in microprocessors industry Digital Circuits Evolution Transistors (MT) 1000 100 10 1 2X growth in 1.96 years! 486 Pentium proc P6 286 386 0.1 8085 8086 Transistors 0.01 on Lead 4004 8008 8080 Microprocessors double every 2 years 0.001 1970 1980 1990 2000 2010 Year Rabaey, 2005 Systems with digital integrated circuits - Introduction 10
Evolution of microprocessors working frequency by 2010 Digital Circuits Evolution Frequency (Mhz) 10000 1000 100 10 1 0.1 8085 8008 4004 8080 8086 Doubles every 2 years 286 386 P6 Pentium proc 486 1970 1980 1990 2000 2010 Year Lead Microprocessors frequency doubles every 2 years Rabaey, 2005 Systems with digital integrated circuits - Introduction 11
Increasing Microprocessors power dissipation until 2000 100 Digital Circuits Evolution Power (Watts) 10 1 8085 8080 8008 4004 8086 286 386 486 P6 Pentium proc 0.1 1971 1974 1978 1985 1992 2000 Year Lead Microprocessors power continues to increase Rabaey, 2005 Systems with digital integrated circuits - Introduction 12
Power consumption will increases to unmanageable values Digital Circuits Evolution Power (Watts) 100000 10000 1000 100 10 1 0.1 8085 8086286 386 486 4004 80088080 Pentium proc 18KW 5KW 1.5KW 500W 1971 1974 1978 1985 1992 2000 2004 2008 Year Power delivery and dissipation will be prohibitive Rabaey, 2005 Systems with digital integrated circuits - Introduction 13
Digital Circuits Evolution Intel Pentium Processor (IV) Systems with digital integrated circuits - Introduction 14
Digital Circuits Evolution Evaluating the results of a digital circuit design Systems with digital integrated circuits - Introduction 15
CMOS technology How to implement digital integrated circuits : Single die Wafer Going up to 12 (30cm) Systems with digital integrated circuits - Introduction 16
Some examples of digital integrated circuit parameters : Digital Circuits Evolution Chip Metal layers Line width Wafer cost Def./ cm 2 Area mm 2 Dies/ wafer Yield Die cost 386DX 2 0.90 $900 1.0 43 360 71% $4 486 DX2 3 0.80 $1200 1.0 81 181 54% $12 Power PC 601 4 0.80 $1700 1.3 121 115 28% $53 HP PA 7100 3 0.80 $1300 1.0 196 66 27% $73 DEC Alpha 3 0.70 $1500 1.2 234 53 19% $149 Super Sparc 3 0.70 $1700 1.6 256 48 13% $272 Pentium 3 0.80 $1500 1.5 296 40 9% $417 Systems with digital integrated circuits - Introduction 17
Digital Circuits Design Principal design goals The design of a CID must follow the highest speed but also the power consumed This is alongside occupying a smaller surface than the implemented circuit As a measure of the quality of the switching circuits, the product of the delay time and the power consumed, a parameter called power-delay product (PDP) In general pentru o anumita tehnologie si o topologie data, PDP este constant In the case of CMOS circuits if the propagation time is to decrease, the transistors are resized by increasing the width of the channel; n this way, the surface of the transistor increases, which leads to the increase of the current and the power consumed, keeping the PDP constant Power-Delay Product (PDP)= E = Energy per operation = P av t p Systems with digital integrated circuits - Introduction 18
Digital Circuits Design Evaluating the results of a digital circuit design Major targets: Working speed (delay time, working frequency) Power disipation Occupied area by a specified circuit Secondary targets Cost Reliability Scalability The energy required to achieve a function Systems with digital integrated circuits - Introduction 19
Digital Circuits Design Design abstraction levels in digital circuits SYSTEM MODULE + GATE CIRCUIT S n+ G DEVICE n+ D Systems with digital integrated circuits - Introduction 20
Digital Circuits Design In ce directie evolueaza proiectarea circuitelor digitale VLSI The technology evolves in the sense of decreasing the size by 0.7 / generation With each generation you can integrate 2 times more features on the chip; the cost of the chip does not increase significantly Cost per feature is down 2 times This has as a consequence a growing number of functions that must be projected by a growing number of human designers This requires a more efficient design method Such a method is to increase abstraction levels as well as scalability Passing from one generation to another is done by applying a constant of all dimensions in the old project Systems with digital integrated circuits - Introduction 21