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1. MLSU
CLASS- BCA 1st SEMESTER
TOPIC– logicAL FAMILIES

2. PRESENTED BY:-
VAISHALI MANDOWARA
UNDER GUIDENCE OF:-
Sonu Upadhyay Mam

3. Logic Family
• Logic Families indicate the type of logic circuit
used in the IC.
• A Circuit configuration or arrangement of the
circuit elements in a special manner will result in
a particular Logic Family.
• The set of digital ICs belonging to the same logic
family are electrically compatible with each other

4. Characteristics of Logic Families
The main characteristics of Logic families include:
• Speed
• Fan-in
• Fan-out
• Noise Immunity
• Power Dissipation

5. Speed: Speed of a logic circuit is determined by the time between the
application of input and change in the output of the circuit.
Fan-in: It determines the number of inputs the logic gate can
handle.
Fan-out: Determines the number of circuits that a gate can drive.
Noise Immunity: Maximum noise that a circuit can withstand without
affecting the output.
Power: When a circuit switches from one state to the other, power
dissipates.

6. basic Classification of Logic Families are as
follows:
• Bipolar Devices
• Metal Oxide Semiconductor Devices
• Hybrid Device

7. Bipolar families
• Bipolar transistors are fabricated on a chip in
digital integrated circuits.
• Bipolar technology is preferred for SSI [ Small
scale integration ] and MSI [ Medium scale
integration ] because it is faster.

8. Types of Bipolar Families:
• Diode Logic (DL)
• Resistor Transistor Logic (RTL)
• Diode Transistor Logic (DTL)
• Transistor- Transistor Logic (TTL)
• Emitter Coupled Logic (ECL) or Current Mode
Logic (CML)
• Integrated Injection Logic (IIL)

9. Diode Logic
• In DL (diode logic), only Diode and Resistors
are used for implementing a particular Logic.
Remember that the Diode conducts only when
it is Forward Biased.

10. Disadvantages of Diode Logic
• Diode Logic suffers from voltage degradation
from one stage to the next.
• Diode Logic only permits OR and AND
functions

11. Resistor Transistor Logic
In RTL (resistor transistor logic), all the logic are implemented
using resistors and transistors. One basic thing about the
transistor (NPN), is that HIGH at input causes output to be
LOW (i.e. like a inverter). In the case of PNP transistor, the
LOW at input causes output to be HIGH.

12. Advantage:
• Less number of Transistors
Disadvantage:
• High Power Dissipation
• Low Fan In

13. Diode Transistor Logic
• In DTL (Diode transistor logic), all the logic is
implemented using diodes and transistors.

14. Disadvantage:
•Propagation Delay is Larger

15. Transistor transistor logic
• The first transistor–transistor logic family of integrated circuits
was introduced by Sylvania as Sylvania Universal High–Level
Logic (SUHL) in 1963. Texas Instruments introduced 7400
Series TTL family in 1964. Transistor–transistor logic uses
bipolar transistors to form its integrated circuits.TTL has
changed significantly over the years, with newer versions
replacing the older types.
• Since the transistors of a standard TTL gate are saturated
switches, minority carrier storage time in each junction limits
the switching speed of the device. Variations on the basic TTL
design are intended to reduce these effects and improve
speed, power consumption, or both.

16. Transistor Transistor Logic

17. Emitter Coupled Logic
• ECL is the fastest of all logic families and
therefore is employed in applications where
very high speed is essential .
• High speeds have become possible in ECL
because transistors are used in differential
amplifier configuration , in which the are
never driven into saturation and thereby the
storage delay time is eliminated.

18. Emitter Coupled Logic

19. Drawbacks of Emitter Coupled Logic:
• Low noise margins
• High power dissipation.
• It uses negative voltage supply which makes it
difficult to use ECL in conjunction with TTL and
MOS circuits.

20. Integrated Injection Logic:
• The integrated injection logic (IIL or I2L) uses
bipolar transistors in a kind of current-steering
arrangement to form its integrated circuits. IIL
is slightly easier to construct on an integrated
circuit, and so was popular for early VLSI
circuits.

21. MOS Families
• MOS stands for Metal Oxide Semiconductor.
• In these MOSFETs (Metal oxide semiconductor
field-effect transistor) are fabricated on chip.
• It is used in LSI [Large scale integration] field
because more MOSFETs can be packed into
the same chip area.

22. Types of MOS Families:
• P-MOS Family
• N-MOS Family
• C-MOS Family

23. PMOS
• PMOS stands for P-channel MOSFETs.
• It is the oldest and slowest type of technology.
• PMOS is the first high density MOS circuit
technology to be produced
• It makes the use of enhancement mode P-
channel MOSFET transistors in forming the
basic gate building blocks.
• There are no resistors in this circuits.

24. NMOS
• N-MOS stands for N-channel MOSFETs.
• N-MOS devices were developed as processing
technology improved.
• N-MOS devices are most common because N-
channel processing is easier than P-channel
processing.
• The N-MOS are widely used in
microproccessors and microcircuits.

25. CMOS
• CMOS stands for complementary MOSFETs.
• CMOS devices are chips in which both P-
channel and N-channel enhancement
MOSFETs are connected in a push-pull
arrangement.
• CMOS are simple , small in size ,cheaper in
fabrication and consume very little power.

26. Hybrid Family:
• Bi-CMOS Family

27. BICMOS
• One major improvement was to combine CMOS
inputs and TTL drivers to form of a new type of
logic devices called Bi-CMOS logic.
• In the 1990s,modern integrated circuit fabrication
technologies began to make Bi-CMOS a reality.
• This technology rapidly found application in
amplifiers and analog power management
circuits, and has some advantages in digital logic.
• Bi-CMOS circuits use the characteristics of each
type of transistor most appropriately.

28. Highlights
• RTL and DTL families have become obsolete
because of their low speed , high power
dissipation , and low fan-out.
• TTL is the most popular general purpose logic
family. It is available in different series with a
wide range of operating speed, power dissipation
and fan-out.
• ECL is the fastest logic family. For interfacing
other logic families level-shifting networks are
required.

29. •IIL is the only saturated bipolar logic family suitable
for LSI because of small silicon chip area requirement
and low power consumption . Because of low voltage
requirement , it is highly suitable for battery operated
systems.
•MOS devices occupy a very small fraction of silicon
chip area as compared to bipolar devices and need
very small power.
•The main disadvantage of MOS logic family is low
speed , which is being improved upon by
improvements in technology of MOS fabrications.

30. •IIL has the highest packing density and is
mainly suitable for VLSI and ULSI.
•CMOS has slow speed but very small
physical size and simple geometry . Its
power dissipation is very small. It is widely
used in electronic wrist watches,
calculators, portable computers etc.