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Advantage of synchronous sequential circuits over asynchronous one is:

  1. Lower hardware requirement
  2. Better noise immunity
  3. Faster operation
  4. All of the above
in Digital Logic by Boss (32.5k points)
retagged by | 4.6k views
+1
I think none of the above answer is correct.Someone verify.
0
b is obvious rt?
+1

Sir ,check the below link.

click here
 

0
That also says option b rt?
+1
Sir, I don,t know but it's saying:

Asynchronous circuits seem to be a good candidate to alleviate the problems originated by simultaneous switching noise.So I think B is also not correct.
Sir, Actually I am not able to interpret these statement correctly.
+1

However, they are also more sensitive than synchronous ones to spurious signal transitions and delay variations produced by crosstalk noise.

If we think simple, synchronous circuits have better noise immunity and this should be given in digital logic texts. 

0
As latches are level triggered, any noise during the level will affect their output right?
+1

@arjun

you said it reverse ..

" If we think simple, synchronous circuits have better noise immunity " - This is reverse statement as you said .

This paper says " "Asynchronous circuits seem to be a good candidate to reduce the problems originated by simultaneous switching noise.  However, they are also more sensitive than synchronous ones to spurious signal transitions .... " This line means asynchronous circuits are better to handle noise than synchronous circuits

. So option B is not true here.. as question asked Advantage of synchronous sequential circuits over asynchronous one .

@Manojk  @kapil and @sh!va please cross check it once ..

+1

Another proof 

according to this paragraph asynchronous circuits have better noise immunity than synchronous ones ...

+1

I got this from Wikipedia. Check this link https://en.wikipedia.org/wiki/Asynchronous_circuit

In the Benefits tab we can get following info

  • Less severe electromagnetic interference (EMI). Synchronous circuits create a great deal of EMI in the frequency band at (or very near) their clock frequency and its harmonics; asynchronous circuits generate EMI patterns which are much more evenly spread across the spectrum.
  • In asynchronous circuits, local signaling eliminates the need for global synchronization which exploits some potential advantages in comparison with synchronous ones. They have shown potential specifications in low power consumption, design reuse, improved noise immunity and electromagnetic compatibility. Asynchronous circuits are more tolerant to process variations and external voltage fluctuations.

So I also think option B is wrong

0
@Arjun Sir Can u please explain in more detail why option B is correct

3 Answers

+2 votes

no option is correct

i copied and pasted the bikram sir comment because this content is good but nobody is focusing on this comment due to large no of comment in this question(all below content is copy paste i did not change anything)

Option A : Lower hardware requirement , is also wrong option .

Plz read my below analysis :

  1. Question asked advantage of synchronous circuits over asynchronous ones ..
  2. see below table for Synchronous Vs Asynchronous 

Synchronous Sequential Circuit is based on state time defined by external means such as clock. 

Asynchronous Sequential Circuit is a circuit whose state time depends solely upon the internal logic circuit delays. [1]
 Logic Gates are required based on design   No extra Logic Gates are required [2]
In Synchronous circuit memory element or digital storage is there and cost is more due to extra hardware.  In Asynchronous ones no such memory element present and cost is also less.[3]

See the first diagram here [3] http://www.ee.surrey.ac.uk/Projects/CAL/seq-switching/synchronous_and_asynchronous_cir.htm 

All these points only means that Asynchronous circuit have less hardware requirement than Synchronous ones .. and the question asked reverse !!

References:

[1] http://verticalhorizons.in/difference-between-synchronous-and-asynchronous-sequential-circuit/

[2] http://www.navodayaengg.in/wp-content/uploads/2015/09/U6-L_47-Difference-between-Asynchronous-and-Synchronous-Counter1.pdf

Hope i am clear now , this question is Wrongly framed and no options are correct !!

by Boss (10.3k points)
0 votes
Is it D ?
by
0
No options are correct .
0
Why option A is not correct
0 votes

A is the best answer here. Synchronous circuits need less stringent hazard management mechanism. 

https://gateoverflow.in/516/gate1991-03-ii

by Veteran (425k points)
0

Here https://gateoverflow.in/516/gate1991-03-ii option B is different than option B in this particular question.

"Asynchronous circuits seem to be a good candidate to alleviate the problems originated by simultaneous switching noise.  However, they are also more sensitive than synchronous ones to spurious signal transitions and delay variations produced by crosstalk noise. "

this means asynchronous circuits are better to handle noise than synchronous circuits ...

But question asked Advantage of synchronous sequential circuits over asynchronous one is:

so better noise immunity is certainly not an advantage :)  rather asynchronous is better immune to noise than synchronous ones ...

+2
Yes B is wrong( Asked advantage of synchronous) but since asynchronous has better noise immunity.
0
Sir why option A is not correct. I could not find explanation anywhere
0

Yes, B is false. 

http://www.cs.columbia.edu/~nowick/async-applications-PIEEE-99-berkel-josephs-nowick-published.pdf

A is probably the answer here -- in synchronous circuits we need a clock -- but it also avoids the need of complex hazard avoidance mechanism. 

0

@Arjun

see this question, https://gateoverflow.in/516/gate1991-03-ii the option C is false . The same option is here also , so it is false.

This ISRO question is wrong actually with no options are correct. 

0
@Bikram in C option there I have mentioned assuming no hazards.
+3

@Arjun and @anchitjindal 

Option A : Lower hardware requirement , is also wrong option .

Plz read my below analysis :

  1. Question asked advantage of synchronous circuits over asynchronous ones ..
  2. see below table for Synchronous Vs Asynchronous 

Synchronous Sequential Circuit is based on state time defined by external means such as clock. 

Asynchronous Sequential Circuit is a circuit whose state time depends solely upon the internal logic circuit delays. [1]
 Logic Gates are required based on design   No extra Logic Gates are required [2]
In Synchronous circuit memory element or digital storage is there and cost is more due to extra hardware.  In Asynchronous ones no such memory element present and cost is also less .[3]

See the first diagram here [3] http://www.ee.surrey.ac.uk/Projects/CAL/seq-switching/synchronous_and_asynchronous_cir.htm 

All these points only means that Asynchronous circuit have less hardware requirement than Synchronous ones .. and the question asked reverse !!

References:

[1] http://verticalhorizons.in/difference-between-synchronous-and-asynchronous-sequential-circuit/

[2] http://www.navodayaengg.in/wp-content/uploads/2015/09/U6-L_47-Difference-between-Asynchronous-and-Synchronous-Counter1.pdf

Hope i am clear now , this question is Wrongly framed and no options are correct !!

+4
ISRO key says none of the options are correct :)
+6
@arjun

I told the same in my above comments :) i know it was wrongly framed !!
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