Digital electronices

1. Name Id
SABBIR AHMED 153-15-644
ROBIN HOSSIN 153-15-643
MAHAMUL HASAN 153-15-642

2. Topic Name

3. What is decoder?
A decoder is a digital circuit that detects the
presence of a specified combination of
bits(code) on its inputs and indicates the
presence of that code by a specified output
level.

4. type of decoder
There are different types of Decoder available in the market 2-to-4 line
decoder, 3-to-8 line decoder or 4-to-16 line decoder, where 2, 3, and 4
are the numbers of inputs to the decoders and 4, 8, and 16 are the
number of output assigned to them. We can form a 3-to-8 line decoder
by using two 2-to-4 line Decoders with enable inputs. Similarly, we can
also form a 4-to-16 line Decoder by cascading two 3-to-8 line Decoders
or four 2-to-4 line Decoders

5. 3 to 8 decoder
BOLEAN FUCTION:
Do= A`B`C` D5= AB`C
D1=A`B`C D6= ABC`
D2= A`BC` D7= ABC
D3= A`BC
D4= AB`C`

6. Logic diagram of 3 to 8 decoder

7. Applications of Decoders
Decoders are greatly used in applications where the particular
output or group of outputs to be activated only on the occurrence of
a specific combination of input levels. Very often these input levels
are provided by the outputs of a register or counter.
When the counter or register continuously pulse the decoder inputs,
the outputs will be activated sequentially. And these outputs can be
used as sequencing signals or timing signals to switch the devices
at particular times.

8. What is Encoder?
An encoder is a device, circuit,
transducer, software program, algorithm
or person that converts information from
one format or code to another. The
purpose of encoder is standardization,
speed, secrecy, security, or saving space
by shrinking size. Encoders are
combinational logic circuits and they are
exactly opposite of decoders. They
accept one or more inputs and generate a
multibit output code.

9. types of encoder
• There are 7 types of encoder:-
(1) Rotary encoder or Shaft
encoder
(2) Incremental Encoder
(3) Absolute Position encoder
• (4) Quadrature
(5) Linear Encoder.
(6) Open Collector Encoder
(7) Binary Code Encoder

10. The Decimal to BCD Encoder
• From the truth table, the outputs can be
expressed by following Boolean Function.
• Note: Below boolean functions are formed by
ORing all the input lines for which output is 1. For
instance Y0 is 1 for D1, D3, D5, D7 & D9 input
lines.

11. • From the truth table, the outputs
can be expressed by following
Boolean Function.
• Note: Below boolean functions are
formed by ORing all the input lines
for which output is 1. For instance
Y0 is 1 for D1, D3, D5, D7 & D9 input
lines.
• Y0 = D1 + D3 + D5 + D7 + D9
• Y1 = D2 + D3 + D6 + D7
• Y2 = D4 + D5 + D6 + D7
• Y3 = D8 + D9

12. Encoder Applications
• Encoders are used to translate
rotary or linear motion into a digital
signal. Usually this is for the
purpose of monitoring or controlling
motion parameters such as speed,
rate, direction, distance or
position. When applying encoders,
selecting the optimum model and
specifying the appropriate
configuration are critical for
success. Proper encoder selection
begins by understanding the role of
the encoder in the motion control
system.

13. ENCODERS AND DECODERS
A0
A1
A2
A3
A4
A5
A6
A7
ENCODER
O0
O1
O2
A0
A1
A2
O0
O1
O2
O3
O4
O5
O6
O7
DECODER
ONLY ONE INPUT
ACTIVATED AT A TIME
BINARY CODE OUTPUT
BINARY CODE INPUT
L
ONY ONE OUTPUT
ACTIVATED AT A
TIME

14. Encoders vs Decoders
Binary decoders/encoders
Decoder
Encoder
 2^n-to-n encoder
 Input code : 1-out-of-2^n.
 Output code : Binary Code
 n-to-2^n
 Input code : Binary Code
 Output code :1-out-of-2^n.

15. Questions?
Do you have any questions ?