IC-Logic-Family

Introduction to IC:
-Miniature, low-cost electronics circuits whose components are fabricated
on a single, continuous piece of semiconductor material to perform a high-level
function.
-Usually referred to as a monolithic IC.
-First introduced in 1958
-Categorized as digital or linear ICs or according to the level of complexity
of the IC

Category Number of Gates:
Small scale integration SSI (<12)
Medium scale integration MSI (12 to 99)
Large scale integration LSI (100 to 9999)
Very large scale integration VLSI (10,000 or more)

Classifications of IC logic families:
Digital ICs are classified not only by their logic operation, but also by the specific
logic-circuit family to which they belong. Each logic family has its own basic
electronic circuit upon which more complex digital circuits and functions are

• developed. The main families are:  TTL(Transistor-Transistor Logic), made of bipolar transistors.

•   CMOS(Complementary Metal Oxide Semiconductor) made from MOSFETs

•   ECL(Emitter Coupled Logic) for extremely high speeds

•  NMOS, PMOSfor VLSI large scale integrated circuits.

•   IILintegrated injection logic.

Packaging:
1. Protect the chip from mechanical damage and chemical contamination.
2. Provides a completed unit large enough to handle.
3. It is large enough for electrical connections to be made.
4. Material is molded plastic, epoxy, resin, or silicone. Ceramic used if higher
thermal dissipation capabilities required. Metal/glass used in special cases. Three
most common packages for ICs are:
a) dual-in-line (DIPS) (most common)
b) flat pack
c) axial lead (TO5)

Properties of Digital ICs:
1) Fan-in
Fan-in (input load factor) is the number of input signals that can be connected to a
gate without  causing it to operate outside its intended operating range. It is
expressed in terms of standard inputs or units loads (ULs).
2) Fan-out
Fan-out (output load factor)  is the maximum number of inputs that can be driven
by a logic gate and it is expressed by a number. A fan-out  of 10 means that 10
unit loads can be driven by the gate while still maintaining  the output voltage
within specifications for logic levels 0 and 1.
3) Noise Margin
Noise margin is the ability of the gate to tolerate fluctuations of the voltage levels.
It means that the maximum noise voltage added to the input signal of a digital
circuit that does not cause an undesirable change in the circuit output.
4) Power Dissipation
Power dissipation is the amount of heat (in milliwatts, mW) that the IC dissipates
in the
form of heat.
5) Propagation Delays.
Propagation delay is the delay before a  change in the input is reflected in the
output. It is the average transition delay time for a signal to propagate from input
to output when the binary signals change in value.


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