What is a sequential circuit and What is a combinational circuit?Is there any difference between them? If yes what is it?

Editorial / Best Answer

Answered by: sweta basanta

  • Sep 11th, 2007

Combinational circuit are those whose output depends only upon the present inputs but in sequential circuit the output depends upon both present and past inputs. that is the difference. 

Showing Answers 1 - 15 of 15 Answers


  • Sep 2nd, 2007

Combinational circuit does not have any memory in the feedback path but the sequential circuit has memory in the feedback path.
Ex of SEQ Circuit: Encoder, Decoder etc
Ex of Comb Circuit; Flipflop

sweta basanta

  • Sep 11th, 2007

Combinational circuit are those whose output depends only upon the present inputs but in sequential circuit the output depends upon both present and past inputs. that is the difference. 


  • Oct 29th, 2007

sequential ckt. is a logic ckt whose output at any instant depend upon the past output or input value.
combinational ckt is a ckt whose o/p at anyinstant depend upon only present input.
The sequential ckt involves memory, combinational ckt has no memory


  • Apr 22nd, 2008

The main differance between sequential and combinational circuit is memory. The output of the sequential circuit depend upon the privious input and previous output of the circuit. While in case of combinational, current output is depend on current input only.


  • May 20th, 2008

Sequential circuits are those crt whoese output depond on present input as well as on previos o/p,it has flip flops for temporary storage e.g flip flop & on the other hand the combinational logic crt ae those whoese output only depond on present input only e.g mux,de-mux,encoder,decoder


  • Jul 9th, 2009

Combinational Logic: Output are obtained as soon as inputs are provided. Output is independant of previous OUTPUT states.

Sequential Logic: Output is obtain on the clock or similar control signal. It is also dependant upon previous OUTPUT states.

A sequential circuit uses flip flops. Unlike combinational logic, sequential circuits have state, which means basically, sequential circuits have memory.

The main difference between sequential circuits and combinational circuits is that sequential circuits compute their output based on input and state, and that the state is updated based on a clock. Combinational logic circuits implement Boolean functions, so they are functions only of their inputs, and are not based on clocks.

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satish mb

  • Sep 25th, 2013

Combinational circuits are those whose output depends on only present inputs, sequential circuits are those whose output depends on both present inputs and previous outputs. in combinational circuits the output is synchronous to the input, that is when input is applied then output will come, in sequential circuits input data is synchronous to the clock.

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Mohit Maurya

  • Sep 28th, 2013

Combinatorial circuits are those whose output depends on only present inputs but in Sequential circuits , there is concept of Memory Element .So in Sequential circuits output depends on both present inputs and previous outputs(stored in memory).

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  • Sep 15th, 2016

Examples of sequential circuits are latches (which latch or store the previous value) flipflops, counters, shift registers etc,. and examples of combinational circuits are decoders, encoders, multiplexers, demultiplexers, adders, comparators, substractors etc,.

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  • Apr 13th, 2017

Actually, Combinational circuits are made from logic gates and its output depends on the present input. combining combinational ckts we can make, multiplexer, demux, encoder, decoder, adders etc
However, Sequential circiuts are also made from logic gates but they contain internal memory, so its output depends on present input as well as previous output. they combined to form flipflops,counters,registers etc.

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  • Jun 1st, 2017

Combination circuit does not have memory hence the output of this circuit depends on the present value of input. Examples of combination circuit are decoders, encoders, adders, multiplexers.
Sequential circuits have memory elements hence the output depends on the present state and also the past value of the input. Examples of the sequential circuits are flipflops and latches.

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  • Jul 13th, 2017

The combinational ckt provides output considering only the input, but the sequential ckt provides output by considering both input and its state (Past input)

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Rajdeep Ashok Vartak

  • Aug 10th, 2017

In digital electronics, both circuits are very important. half adder, full adder, half substractor, full substractor, parallel adder, encoder, decoder, multiplexer, demultiplexer etc are under Combination circuits. But counter, flip flop, shift registers, serial adder, sequence generator, logic function generators are under sequential circuits.

Combinational Circuits: Its output depends only on present variable input. It has no propagation time is faster and easy to design.circuit consists of only logic gates are under sequential circuits.

Sequential Circuit: Its output depends not only present state but also past state. It is a combination of combinational circuit and memory elements. memory elements work as a feedback. It has memory. Its propagation is slow and harder to design compare to combinational circuits

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