11-02-2013, 04:07 PM
Why VLSI?
Why VLSI.pdf (Size: 105.28 KB / Downloads: 104)
VLSI and you
Microprocessors:
– personal computers;
– microcontrollers.
DRAM/SRAM.
Special-purpose processors.
Why VLSI?
Integration improves the design:
– lower parasitics = higher speed;
– lower power;
– physically smaller.
Integration reduces manufacturing cost-
(almost) no manual assembly.
Moore’s Law
Gordon Moore: co-founder of Intel.
Predicted that number of transistors per chip
would grow exponentially (double every 18
months).
Exponential improvement in technology is a
natural trend: steam engines, dynamos,
automobiles.
Challenges in VLSI design
Multiple levels of abstraction: transistors to
CPUs.
Multiple and conflicting constraints: low
cost and high performance are often at odds.
Short design time: Late products are often
irrelevant.
Dealing with complexity
Divide-and-conquer: limit the number of
components you deal with at any one time.
Group several components into larger
components:
– transistors form gates;
– gates form functional units;
– functional units form processing elements;
– etc.
Design validation
Must check at every step that errors haven’t
been introduced-the longer an error remains,
the more expensive it becomes to remove it.
Forward checking: compare results of lessand
more-abstract stages.
Back annotation: copy performance
numbers to earlier stages