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VLSI Design Styles
Basic Concepts in VLSI Physical Design Automation
VLSI Design Cycle
• Large number of devices
• Optimization requirements for high performance
• Time-to-market competition
• Cost
1. System specification
2. Functional design
3. Logic design
4. Circuit design
5. Physical design
6. Design verification
7. Fabrication
8. Packaging, testing, and debugging
Physical Design
• Converts a circuit description into a geometric description.
– This description is used for fabrication of the chip.
• Basic steps in the physical design cycle:
1. Partitioning
2. Floorplanning and placement
3. Routing
4. Compaction
n-channel Transistor
n-channel Transistor Operation
n-channel Transistor Layout
p-channel MOS Transistor
Fabrication Layers
MOS Transistor Behavior
Summary of VLSI Layers
VLSI Fabrication
Silicon Wafer
General Design Rules
Types of Fabrication Errors
Width/Spacing Rules (MOSIS)
Poly-Diffusion Interaction
Contacts
Contact Spacing
M2 Contact (Via)
CMOS Layout Example
Stick Diagrams
Static CMOS Inverter
Static CMOS NAND Gate
Static CMOS NOR Gate
Static CMOS Design :: General Rule
Simple Static CMOS Design
Example
Static CMOS Design Example
Layout
VLSI Design Styles
• Programmable Logic Devices
– Programmable Logic Device (PLD)
– Field Programmable Gate Array (FPGA)
– Gate Array
• Standard Cell (Semi-Custom Design)
• Full-Custom Design
Field Programmable Gate Array (FPGA)
Introduction
• User / Field Programmability.
• Array of logic cells connected via routing channels.
• Different types of cells:
– Special I/O cells.
– Logic cells.
• Mainly lookup tables (LUT) with associated registers.
• Interconnection between cells:
– Using SRAM based switches.
– Using antifuse elements