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VLSI & ECAD LAB
Introduction
VLSI
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Since the invention of the first IC (Integrated Circuit), the ability to pack more
and more transistors onto a single chip has doubled roughly every 18 months,
in accordance with the Moore’s Law
By mid eighties, the transistor count on a single chip had already exceeded
1000 and hence came the age of Very Large Scale Integration or VLSI.
Though many improvements have been made and the transistor count is still
rising( NVDIA’s 280 Series GPU has almost 1.4billion transistors), further
names of generations like ULSI are generally avoided.
It was during this time when TTL lost the battle to MOS family owing to the
same problems that had pushed vacuum tubes into negligence, power
dissipation and the limit it imposed on the number of gates that could be placed
on a single die.
VLSI
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The second age of Integrated Circuits revolution started with the introduction
of the first microprocessor, the 4004 by Intel in 1972 and the 8080 in 1974
Today many companies like Texas Instruments, Infineon, Cadence, Synopsys,
Celox Networks, Cisco, Micron Tech, National Semiconductors, ST
Microelectronics, Qualcomm, Lucent, Mentor Graphics, Analog Devices, Intel,
Philips, Motorola and many other firms have been established and are
dedicated to the various fields in "VLSI" like Programmable Logic Devices,
Hardware Descriptive Languages, Design tools, Embedded Systems etc.
Where do we actually see VLSI Technology in action? Everywhere, in personal
computers, cell phones, digital cameras and any electronic gadget.
VLSI DESIGN
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VLSI chiefly comprises of Front End Design and Back End design these days.
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While front end design includes digital design using HDL, design
verification through simulation and other verification techniques,
the design from gates and design for testability,
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Backend design comprises of CMOS library design and its
characterization. It also covers the physical design and fault
simulation.
VLSI is dominated by the CMOS technology
Process technology is rapidly shrinking from 180nm-> 60nm-> 40nm->28nm->
20nm->14nm
ASIC
• Application Specific Integrated Circuit is
an integrated circuit (IC) customized for a
particular use, rather than intended for generalpurpose use`
• Modern ASICs often include
entire microprocessors, memory blocks
including ROM, RAM, EEPROM, Flash and
other large building blocks. Such an ASIC is
often termed a SoC (System-On-Chip)
• Popular ASIC methodologies
– Standard cell design (Semi-custom design)
– Full-custom design
– Cell libraries, IP-based design : soft macros, hard
macros
VLSI(ASIC) DESIGN FLOW
FPGA
• A Field Programmable Gate Array (FPGA) is an integrated circuit designed to be
configured by a customer or a designer after manufacturing—hence "fieldprogrammable“
• The FPGA configuration is generally specified using a hardware description
language (HDL)
• FPGAs can be used to implement any logical function that an ASIC could perform.
The ability to update the functionality after shipping, partial re-configuration of a
portion of the design and the low non-recurring engineering costs relative to an ASIC
design (notwithstanding the generally higher unit cost), offer advantages for many
applications.
• A recent trend has been to take the coarse-grained architectural approach a step further
by combining the logic blocks and interconnects of traditional FPGAs with
embedded microprocessors and related peripherals to form a complete "system on a
programmable chip
FPGA
• FPGAs contain programmable
logic components called "logic blocks", and a
hierarchy of reconfigurable interconnects that
allow the blocks to be "wired together"—
somewhat like many (changeable) logic gates
that can be inter-wired in (many) different
configurations
• The main units of a FPGA are the Logic
Blocks, Input/Output Blocks & the
Programmable Interconnect
• Logic blocks can be configured to perform
complex combinational functions, or merely
simple logic gates like AND and XOR. In most
FPGAs, the logic blocks also include memory
elements, which may be simple flip-flops or
more complete blocks of memory
FPGA
• Applications of FPGAs include digital signal processing, software-defined
radio, aerospace and defense systems, ASIC prototyping, medical imaging, speech
recognition, cryptography, bioinformatics, computer hardware emulation, radio
astronomy, metal detection and a growing range of other areas.