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EE603 – CMOS IC DESIGN
TOPIC 1
Introduction to Integrated
Circuit
Faizah Bt. AmirFaizah Bt. AmirFaizah Bt. AmirFaizah Bt. Amir
Introduction to Integrated Circuit
• explain the historical perspective of integrated circuit
• explain the issues in digital IC design
• explain the quality design metrics of a digital design
Lesson Learning Outcome :
At the end of this session, you should be able to:
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What is an Integrated Circuit ?
A complex set of tiny components and their
interconnections that are imprinted onto a tiny
slice of semiconductor material (e.g silicon).
Integrated circuits are usually called ICs or chips.
Introduction to Integrated Circuit
Introduction to Integrated Circuit
• Different Types of IC Packages
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Introduction to Integrated Circuit
– Evolution of logic complexity in IC
Year Technology No. of
transistors
Example
1947-1950 Transistor 1 -
1951 -1960 Discrete Component 1 FET, Diode
1961 -1966 SSI
- Small scale integration
10 Logic Gates, Flip-flop
1967-1971 MSI
- Medium scale integration
100 – 1000 Counter, Multiplexer
1972-1980 LSI
- Large scale integration
1000 – 20,000 RAM, Microprocessor
1981 -1990 VLSI
- Very large scale integration
20,000 –
1,000,000
16 bits and 32 bits
Microprocessor
1990-2000 ULSI
- Ultra large scale integration
1,000,000 –
10,000,000
Graphic microprocessor
2000 -
nowadays
GSI
- Giga scale integration
> 10,000,000 -
Transistor Revolution
• First Transistor –Bardeen et.al.(Bell Labs)
in 1947
• First Bipolar transistor –Shockley in 1949
• First monolithic IC –Jack Kilby in 1958
• First commercial IC logic gates –Fairchild
1960
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Transistor Revolution
• Dr. John Bardeen, Dr. Walter Brattain, and Dr. William
Shockley discovered the transistor effect and developed the
first device in December, 1947. They were members of the
technical staff at Bell Laboratories in Murray Hill, NJ. They
were awarded the Nobel Prize in physics in 1956.
John Bardeen, William Shockley and Walter Brattain
at Bell Labs, 1948.
1947 First BJT
Bardeen, Shockley, Brattain
(Bell Labs)
Transistor Revolution
• William Shockley developed the theory for the
junction transistor in 1948 at Bell Labs.
• He left for Caltech in 1953 and founded Shockley
Semiconductor in 1956 and starting Silicon Valley
in Mountain View, California.
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Transistor Revolution
• Jack Kilby completed his first integrated circuit on
September 12, 1958 which was actually constructed
on germanium rather than silicon, as he could not find
a suitable piece of silicon at the time.
• The integrated circuit was fully functional, and Texas
Instrument officially announced it in January 1959.
1958: The Integrated Circuit was invented by Jack Kilby
Transistor Revolution
In August 1959 Fairchild Semiconductor begin the
development of an integrated circuit.
Fairchild presented advanced information at
engineering conferences and provided prototype
samples to customers in 1960.
1962 Fairchild IC
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MOSFET TECHNOLOGY
• MOSFET transistor was first proposed and patented by Lilienfeld
(Canada) in 1925 and Heil (England) in 1935.
• The devices was not successfully demonstrated for several years
but only became important in mid and late 1960s.
• Initially semiconductor research had focussed in developing the
bipolar transistor, because they have problems in fabricating
MOSFETs, particularly with the insulating oxide layers.
• Now the technology is one of the most widely used
semiconductor techniques and become one of the principle
elements in integrated circuit technology today.
• Their performance has enabled power consumptions in ICs to be
reduced and enabled the portable gadgets to become a reality.
• As a result of this the MOSFET is the most widely used form of
transistor in existence today.
Moore’s Law
• In 1965, Gordon Moore (Co-Founder of
Intel) predicted that the number of
transistors per chip will grow exponentially
with time.
• He predicted that :
the transistor density will double
every 18-24 months
the chip performance will double
every 18-24 months
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Power Density
Issues in Digital IC Design
Functionality
Cost
Reliability, Robustness
Performance
Time to market
Design Complexity
High Levels of
Abstraction
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QUALITY DESIGN METRICS IN DIGITAL DESIGN
• Functionality
• Cost
– NRE (fixed) costs - design effort
– RE (variable) costs - cost of parts, assembly, test
• Reliability, robustness
– Noise margins
– Noise immunity
• Performance
– Speed (delay)
– Power consumption; energy
• NRE (non-recurring engineering) costs
– Fixed cost to produce the design
• design effort
• design verification effort
• mask generation
– Influenced by the design complexity and designer
productivity
– More pronounced for small volume products
• Recurring costs – proportional to product volume
– Silicon processing
• also proportional to chip area
– Assembly (packaging)
– Test
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• Prime requirement –
IC performs the function it is designed for
• Normal behaviour deviates due to
– variations in the manufacturing process (dimensions and
device parameters vary between runs and even on a
single wafer or die)
– presence of disturbing on- or off-chip noise sources
• Noise: Unwanted variation of voltages or
currents at the logic nodes
• from two wires placed side by side
– inductive coupling
• current change on one wire can
influence signal on the neighbouring
wire
– capacitive coupling
• voltage change on one wire can
influence signal on the neighbouring
wire
• cross talk
• from noise on the power
and ground supply rails
– can influence signal
levels in the gate
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Inverter Voltage Transfer Characteristic
(VTC)
in out
VOH , VIH - nominal high
voltage
VOL, VIL - nominal low
voltage
VM – gate or switching
threshold voltage
VM can be found graphically
at the intersection of the
VTC curve and the line
given by Vout = Vin.
The gate threshold voltage
presents the midpoint of the
switching characteristics.IL IH
• The regions of acceptable high and low voltages are
delimited by VIH and VIL that represent the points on the
VTC curve where the gain = -1 or dVout/dVin = -1
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Noise Margins is a measure of the
sensitivity of a gate to noise.
Noise margins represent the levels of
noise that can be sustained when gates
are cascaded.
For robust circuits, we want the “0” and
“1” intervals to be as large as possible.
Large noise margins are desirable.
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• A gate with regenerative property ensure that a
disturbed signal converges back to a nominal voltage
level.
v0 v1 v2
v3 v4 v5
v6
The signal voltage gradually
converges to the nominal signal
after a number of inverter stages,
as indicated by the arrows.
The signal does not converge to
any of the nominal voltage levels
but to an intermediate voltage
level. Hence, the characteristic is
nonregenerative.
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• Noise margin expresses the ability of a circuit to
overpower a noise source.
– noise sources: supply noise, cross talk, interference,
offset.
• Noise immunity, on the other hand, expresses the
ability of the system to process and transmit information
correctly in the presence of noise.
• Noise immunity is the ability of a circuit to reject a
noise source rather than overpower it.
• A gate must be unidirectional: changes in an output
level should not appear at any unchanging input of the
same circuit.
– In real circuits full directivity is an illusion (e.g., due to capacitive
coupling between inputs and outputs).
• Key metrics: output impedance of the driver and
input impedance of the receiver.
– ideally, the output impedance of the driver should be zero.
– input impedance of the receiver should be infinity.
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Fan-out – number of load gates
connected to the output of the
driving gate.
o gates with large fan-out are slower
Fan-in – the number of inputs to
the gate.
o gates with large fan-in are bigger
and slower
• The ideal gate should have:
– infinite gain in the transition region
– a gate threshold located in the middle of the logic swing
– high and low noise margins equal to half the swing
– input and output impedances of infinity and zero, respectively.
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Performance
• The performance of a digital circuit is
expressed by the propagation delay and
the power consumption of a gate.
•The propagation delay, tp of a gate defines
how quickly it responds to a change at its
input(s).
• It expresses the delay experienced by a
signal when passing through a gate.
• It is measured between the
50% transition points of the
input and output waveforms.
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• Power consumption: how much energy is consumed
per operation and how much heat the circuit dissipates.
– supply line sizing (determined by peak power)
Ppeak = Vdd ipeak
– battery lifetime (determined by average power dissipation)
p(t) = v(t)i(t) = Vddi(t)
Pavg= 1/T ∫ p(t) dt = Vdd/T ∫ idd(t) dt
– packaging and cooling requirements
• Two important components: static and dynamic
• Propagation delay and the power consumption of a
gate are related.
• Propagation delay is (mostly) determined by the
speed at which a given amount of energy can be
stored on the gate capacitors.
– the faster the energy transfer (higher power dissipation) the
faster the gate.
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• Digital integrated circuits have come a long
way and still have quite some potential left for
the coming decades.
• A lot of issues and challenges in digital
integrated circuit design and the potential
solutions are needed in order to survive in the
industry.
• Design metrics is used to evaluate the quality
of a design: cost, functionality, robustness,
performance and energy/power dissipation.
