9.1 Sspd_chapter 7_part 1_the art of microchip fabrication transforms

SSPD_Chapter 7_Part 1_The Art of Microchip Fabrication transforms into HiTech Computer-Aided VLSI DESIGN and Microchip Fabrication.

[This chapter is based on the write up titled ‘Technology Computer Aided Design for Si, SiGe and GaAs Integrated Circuits’ edited by G.A. Armstrong and C.K. Maiti as a part of IET Circuits, Devices and Systems Series 21]

In last 60 years, the successful scaling of the silicon devices and advances in processing technologies has enabled us to achieve dizzying heights in terms of complexity of electronics systems integrated till date. The advanced level of integration and complexity achieved is testified by 3D HDTV and 4G Mobile Communication.

Today we have successfully marched from micro era to nano era of IC Technology and reached giga scale level of integration but we are running into serious road blocks . These road blocks are due to reaching the physical limits of the devices and quantum mechanics will have to be invoked for further scaling of the devices.

• Principles of VLSI Design

[CMOS VLSI Design: A Circuits and Systems Perspective, Third Edition.by Neil H.E. Weste and David Harris.ISBN: 0-321-14901-7, Addison Wesley.

Supplementary texts : Digital Integrated Circuit Design by Ken Martin, Oxford University Press (2000). Digital Integrated Circuits, A Design Perspective, Second Edition by J. Rabaey, A. Chandrakasan and B. Nikolic, Prentice Hall (2003).]

What are the concepts and techniques of modern integrated circuit design (CMOS VLSI).

How to design integrated circuits using Commercial Computer Aided Design (CAD) Tools (CADENCE).

The Design Process : An iterative process that refines an idea to a manufacturable device through at least five levels of design abstraction.

Top level : The idea refined into a set of requirements called specifications:

What does the chip do?

How fast does it need to operate in order to be competitive?

How big will it be?

How much power will it consume?

Design Constraints:

Speed, power and area.

Abstraction : A very effective means of dealing with design complexity.

Creating a model at a higher level of abstraction involves replacing detail at

the lower level with simplifications.

Simulation : The functional behavior of the design (or a parameter such as power)

is determined by applying a set of excitation vectors to a circuit model.

Levels of abstraction:

(1) Functional (architecture)

(2) Register Transfer Level (microarchitecture, block)

(3) Logic Design

(4) Circuit Design

(5) Physical Design

Hardware Description Languages

Verilog, VHDL etc.

VHDL Example: 32 bit adder

Entity ALU32 is port(

A, B: in bit_vector(31 downto 0);

.....) end ALU32;

if (a=b) then

sum<= ‘0’ ;

else

sum<= (a or b);

end if;

This is Behavioural Simulation.

In the following four diagrams the four levels of abstraction are introduced.

Figure 7.1. VLSI Design at RTL and Logic Design Level.