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.