Systems with Digital Integrated Circuits

Transcription

1 Systems with Digital Integrated Circuits Introduction Sorin Hintea Basis of Electronics Departament

2 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

3 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

4 Ideal and real digital circuits Behaviour of real digital circuits V out (V) t p = 0.69 C L (R eqn +R eqp )/ t (sec) x Blue - ideal input signal; Black real output signal Time behavior of digital circuit s output Systems with digital integrated circuits - Introduction 4

5 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

6 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

7 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

8 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 Electronics, April 19, Systems with digital integrated circuits - Introduction 8

9 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, i486 Pentium i Pentium III Pentium II Pentium Pro Source: Intel DupaRabaey, 2005 Projected Systems with digital integrated circuits - Introduction 9

10 The evolution of the number of chip transistors by 2010 in microprocessors industry Digital Circuits Evolution Transistors (MT) X growth in 1.96 years! 486 Pentium proc P Transistors 0.01 on Lead Microprocessors double every 2 years Year Rabaey, 2005 Systems with digital integrated circuits - Introduction 10

11 Evolution of microprocessors working frequency by 2010 Digital Circuits Evolution Frequency (Mhz) Doubles every 2 years P6 Pentium proc Year Lead Microprocessors frequency doubles every 2 years Rabaey, 2005 Systems with digital integrated circuits - Introduction 11

12 Increasing Microprocessors power dissipation until Digital Circuits Evolution Power (Watts) P6 Pentium proc Year Lead Microprocessors power continues to increase Rabaey, 2005 Systems with digital integrated circuits - Introduction 12

13 Power consumption will increases to unmanageable values Digital Circuits Evolution Power (Watts) Pentium proc 18KW 5KW 1.5KW 500W Year Power delivery and dissipation will be prohibitive Rabaey, 2005 Systems with digital integrated circuits - Introduction 13

14 Digital Circuits Evolution Intel Pentium Processor (IV) Systems with digital integrated circuits - Introduction 14

15 Digital Circuits Evolution Evaluating the results of a digital circuit design Systems with digital integrated circuits - Introduction 15

16 CMOS technology How to implement digital integrated circuits : Single die Wafer Going up to 12 (30cm) Systems with digital integrated circuits - Introduction 16

17 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 $ % $4 486 DX $ % $12 Power PC $ % $53 HP PA $ % $73 DEC Alpha $ % $149 Super Sparc $ % $272 Pentium $ % $417 Systems with digital integrated circuits - Introduction 17

18 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

19 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

20 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

21 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