Digital IC Family
Digital IC
Introduction
• Digital ICs are more reliable by reducing the number of
external interconnections from one device to another.
• Before ICs, every circuit connection was from one
discrete component to another.
Cont.,
• A logic family refers to digital integrated circuit
devices which are constructed with a combination
of electronic gates.
•
A family has its own power supply voltage and
distinct logic levels.
Cont.,
• Each family has its own characteristics, advantages and
disadvantages.
• Also within each family, there is a range of voltages
which may be high level or low level.
Cont.,
• The various logic families can be placed into two brand
categories according to the IC fabrication process.
• Bipolar
• Metal-oxide semiconductor (MOS)
Bipolar Logic family
Metal-oxide semiconductor Logic
family
Bipolar Logic families
• The important elements of a bipolar IC are resistors,
transistors and diodes.
• Based on the two main operations of bipolar ICs, i.e.,
• Saturated
• Non-saturated.
Saturated bipolar Logic families
• Resistor-Transistor Logic (RTL)
• Direct-Coupled Transistor Logic (DCTL)
• Diode-Transistor Logic (DTL)
• High Threshold Logic (HTL)
• Transistor-Transistor Logic (TTL)
• Integrated-Injection Logic (IIL)
Resistor-Transistor Logic (RTL)
Direct-Coupled Transistor Logic
(DCTL)
Diode-Transistor Logic (DTL)
High Threshold Logic (HTL)
Transistor-Transistor Logic (TTL)
Integrated-Injection Logic (IIL)
Non saturated Logic families
• Schottky TTL
• Emitter-coupled Logic (ECL)
Emitter-coupled Logic (ECL)
Metal Oxide Semiconductor (MOS)
The MOS families include
• PMOS
p-channel MOSFETs
• NMOS
n-channel MOSFETs
• CMOS
Complementary MOSFETs
PMOS p-channel MOSFETs
NMOS n-channel MOSFETs
CMOS Complementary MOSFETs
Characteristics of Digital ICs
• Speed of operation
• Power dissipation
• Fan-in
• Fan-out
Cont.,
• Noise immunity
• Operating temperature
• Power supply requirements
Speed of operation
• The speed of operation of an IC is expressed in terms of
propagation delay.
• Propagation delay is defined as the time taken for the
output of a gate to change after the inputs have changed
Cont.,
• The time difference between the application of input
and appearance of output is also called as propagation
delay.
Power dissipation
• Power dissipation is the nature of the power consumed
by a logic gate when fully driven by all its inputs.
• It is expressed in mill watts or nano watts
Fan in
• The fan-in of a gate is the number of inputs connected
to the gate without degradation in the voltage levels.
Fan out
• Fan out is the maximum number of similar logic gates
that a gate can drive without any degradation in voltage
levels.
Noise immunity
• The noise immunity of a logic circuit refers to the circuit
ability to tolerate noise without causing spurious
changes in the output voltage.
• A quantitative measure of the noise immunity is called
noise margin.
Operating Temperature
• ALL IC gates are semiconductor devices that are
temperature-sensitive by nature.
• The operating temperature ranges for and IC vary from
00 C to +700 C for consumer and industrial applications
and from -550 C to + 1250 C for military applications
Power supply requirements
• The amount of power and supply voltage required by an
IC are the main parameters to be taken into
consideration while choosing a proper power supply
The End
……Thank you……
M.S.P.V.L. Polytechnic College,
Pavoorchatram.