chap-1-2.pdf basic concepts of CAD for VLSI

CAD for VLSI

1. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
1
March 25, 1999
THE VLSI DESIGN PROBLEM
Realize a given specification on silicon, optimizing the following enti-
ties:
* area (yield)
* power dissipation
* speed
* design time
* testability
Optimization cannot be done in one step
partition problem and optimize subproblems.

2. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
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March 25, 1999
HIERARCHY AND ABSTRACTION
Hierarchy:
something is composed of simpler things
Abstraction:
when looking at a certain level, you don't need to know all
details of the lower levels.

3. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
3
March 25, 1999
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4. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
4
March 25, 1999
DESIGN DOMAINS
Design domains:
*
behavioral:
black box view
*
structural:
interconnection of subblocks
*
physical:
layout properties
Each design domain has its own hierarchy.

5. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
5
March 25, 1999
GAJSKI'S Y-CHART
BEHAVIORAL DOMAIN STRUCTURAL DOMAIN
PHYSICAL DOMAIN
Physical partitions
Floor plans
Module layout
Cell layout
Transistor layout
Systems
Algorithms
Register transfers
Logic
Transfer functions
Processors
ALU's, RAM, etc.
Gates, flip-flops, etc.
Transistors

6. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
6
March 25, 1999
TOP-DOWN STRUCTURAL DESIGN
BEHAVIORAL DOMAINSTRUCTURAL DOMAIN
PHYSICAL DOMAIN
Physical partitions
Floor plans
Module layout
Cell layout
Transistor layout
Systems
Algorithms
Register transfers
Logic
Transfer functions
Processors
ALU's, RAM, etc.
Gates, flip-flops, etc.
Transistors

7. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
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March 25, 1999
DESIGN ACTIONS
Synthesis:
increasing information about the design by providing more
detail (within the same or another design domain).
Verification:
checking whether a synthesis step has left the specifica-
tion intact.
Analysis:
collecting information on the quality of the design.
Optimization:
increasing the quality of the design by rearrangements
in a given description.
Design Management:
storage of design data, cooperation between
tools, design flow, etc.

8. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
8
March 25, 1999
DESIGN METHODS
Can the designer control the shape of all mask patterns?
* Yes full-custom fabrication
* No semi-custom fabrication, e.g. gate array, sea of gates
Can the designer specify the design up to the level of individual transis-
tors?
* Yes full-custom design
*No semi-custom design e.g. by means of
standard cells, module
generators,
etc.
SPECIFIC DESIGN METHODS REQUIRE SPECIFIC CAD TOOLS!

9. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
9
March 25, 1999
DESIGN ISSUES AND TOOLS
System-level design:
* Partitioning into hardware and software, co-design, co-simulation,
etc.
* Cost estimation, design-space exploration
Algorithmic-level design:
* Behavioral descriptions (e.g. in VHDL)
* High-level simulation
From algorithms to hardware modules:
* High-level (or architectural) synthesis

10. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
10
March 25, 1999
DESIGN ISSUES AND TOOLS (Ctd.)
Logic design:
* Schematic entry
* Register-transfer level and logic synthesis
* Gate-level simulation (functionality, power)
* Timing analysis
* Formal verification
Transistor-level design:
* Switch-level simulation
* Circuit simulation

11. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
11
March 25, 1999
DESIGN ISSUES AND TOOLS (Ctd.)
Layout design:
* Floorplanning
* Module and cell generation
* Placement and routing
* Layout editing: symbolic and at mask level
* Layout compaction
* Design-rule checking
* Layout extraction
Design management:
* Data bases, frame works, etc.

12. ALGORITHMS FOR VLSI DESIGN AUTOMATION
DESIGN METHODOLOGIES AND SURVEY OF TOOLS
12
March 25, 1999
SILICON COMPILATION
Analogy with compilers for programming languages:
from algorithm to machine instructions
In VLSI:
from algorithm to mask patterns
Current practice:
* this ideal is approached more and more (e.g. VHDL synthesis);
* still far away from a single
push-button
operation.