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Combinational circuit

Combinational circuits are defined as the time independent circuits which do not depends upon previous inputs to generate any output are termed as combinational circuits.

Combinational circuit

Combinational circuit

• In this output depends only upon present

input.

• There is no feedback between input and

output.

• Elementary building blocks: Logic gates

• Used for arithmetic as well as Boolean

operations.

Combinational circuit

Combinational circuits don’t have capability to store

any state.

As combinational circuits don’t have clock, they don’t

require triggering.

These circuits do not have any memory element.

Examples – Encoder, Decoder, Multiplexer,

Demultiplexer

Multiplexer

Multiplexer is a special type of combinational

circuit. There are n-data inputs, one output and

S select inputs . It is a digital circuit which

selects one of the n data inputs and routes it to

the output.

multiplexer

MUX4x1

D

B

C

A

a b

Q

multiplexer

multiplexer

a =selection-1 b = selection -2 Output

0 0 A

0 1 B

1 0 C

1 0 D