in Digital Logic retagged by
2,929 views
1 vote
1 vote

In which of the following adder circuits, the carry look ripple delay is eliminated?

  1. Half adder
  2. Full adder
  3. Parallel adder
  4. Carry-look ahead adder
in Digital Logic retagged by
2.9k views

1 comment

Carry look ripple delay is eliminated in Carry-look-ahead adder
0
0

3 Answers

3 votes
3 votes

carry look ripple delay is eliminated in Carry-look-ahead adder as carry is already provided before the operation starts .

carry is calculated as follows:-

Substituting C1 into C2, then C2 into C3, then C3 into ​​​​​​​C4 yields the following expanded equations: 

Here G (carry generator) is equal to 

P(propagate) as follows

 

all the carry are calculated using the above formula and provided to input as mentioned in a diagram. Thus ripple delay is eliminated.

 

 

follow this link for further clarification:- https://www.geeksforgeeks.org/carry-look-ahead-adder/

 

0 votes
0 votes

Option D; as in CLA the carry is generated in parallel. Hence no concept of ripple carry.

Please refer to the carry equation
Where $Gi$ is the generator Function and $Pi$ is the propagation function.
$Gi$ = $AiBi$ (Ai,Bi are Bit pairs of the two n bit numbers)
$Pi$ = $Ai+Bi$ or $Ai ⊕ Bi$
Follow CLA for further clarification.
0 votes
0 votes
option (d) is correct.
Answer:

Related questions