What is difference between buffering and cloning?

[vreddy]

buffering

wat is the difference between cloning & buffering??

thanx

 

[p_shinde]

Re: buffering

cloning u reducing the load on the i/p of a cell by creating a different path.......
buffering u just go on adding buffers in the path .......

 

[ivlsi]

Re: commands for cloning the logic cells

What commands should be used for cloning the logic with high fan-out?

 

[dftrtl]

Re: commands for cloning the logic cells

You need to use commands what you use when you do ECO.
Like add cell and connect.

 

[englishdogg]

manual cloning is cumbersome and then placement as well.
Buffering nowadays is well -done by all products today at syntyhesis and post placement optimization stages.

Cloning is better done when you ahve physical information and can help break down the fanout also and then place the cloned instance near to the rest of the logic that it is talking to

 

[ivlsi]

What cases buffering would help and cloning would not and vice versa?

 

[englishdogg]

@dmitryl

a quick thought tells me buffering offers two main advantages / need - High fanout fixing and addressing drive strength

Cloning also helps high fanout but this ideally should be more placement aware or area aware. For eg if you have a high fanout whose loads are at two ends of the placeable area then a clone at two ends of these loads helps address high fanout + congestion, timing and routing.

most common is the clock gates clone / declone which helps address CG setup times.

hope this helps.

 

[ivlsi]

if you have a high fanout whose loads are at two ends of the placeable area then a clone at two ends of these loads helps

Why buffering would not help in this case?

What cases where the timing could be fixed only by cell cloning and not by buffering (and vice versa)?

 

[englishdogg]

i think the answer is in my earlier append itself - pls note that it does mean that buffering will not be able to solve the high fanout issue if the loads are placed at two different ends - it may but it may add as an overhead to routing resources, congestion. Also will it be optimal adding many buffers across.

My best take would be clone logic in this case and save the above resources instead of adding many buffers. As i mention - cloning also addresses high fanout but this opto trick is more placement / physical aware