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43 Threads found on edaboard.com: Useful Skew
For me, usefull skew is the skew between flops which have timing path in common. I means, the (normal) skew, is for all flops independently if these flops have no common paths.
You can't. There is no such thing as "no" (zero) jitter or skew. If you had a meaningful, quantitative upper limit to these then you could have a chance of meeting that goal. But if your goal is zero, you may as well quit and go into management before you smarten up and become useful. Then you can have all the =0 goals you want and it's Somebody
many ways to fix setup violation after synthesis. 1. size cell and minimize data path delay. 2. check hold margin and useful skew. 3. use LVT cell if all ways can not work. you 'd better add more margin to re-synthesis or re-design.
also check local and useful skew concepts, know how and where you are going to apply these to time your paths better.
jaya sree, latency numbers can be accepted. Can you tell me if clock skew numbers are global skew or local skew? By any chance did you turned on use of useful skew to meet timing? if that is the case and your timing is good. no need to worry. Jay
You cannot always fix all violations using useful skew. useful skew can be used only when you have enough slack on next/previous stages. Without slack values and how much clock tree exception was set, its hard to figure out the issue, but my guess is that you probably went overboard with 'useful (...)
Hi ajesh, The discussion in the following thread will answer your query.. if you still have any doubts please post here... useful?? cheers
Hi tachyons, Please refer & for setup and hold fixing Hope you find it useful... PS: lot of questions in one day..hmm
Hi Kumar, In all probability there will be setup and hold violations along various paths..depending on whether there are positive or negative skews at the end points... But the thing is we may use the same skew for fixing these violations..this is referred to as useful skew...intentional placing skew to (...)
i've that book... i want to know about useful skew,local skew ,global skew and all those things..it's not given in this book Dear Biku, useful skew:- This is the min skew required to meet both setup and hold violations of a path. Sometimes, what happens, when we (...)
What is useful skew with respect to CTS?.
Significance of Global skew is one need not perform CTO as Setup and Hold Check is already done as useful skew optmizises in such a way that there is no setup violations. For more info:
We usually build a zero skew clock tree first when clock insertion. But If there are some timing violations, we will try to build a useful skew clock tree. The useful skew is the manual skew we add on the clock tree to balance the current timing path and the next timing path.
First a correction: sd and ss are not skews, they are the insertion delays to those registers. Their difference is the skew. Yes, skew can be beneficial in some cases. It is called "useful skew". The idea is that one register-to-register stage can have plenty of positive slack while the next stage has a (...)
Hi all, 1. How operating voltage can be used to satisfy timing? 2. What is the difference between local-skew, global-skew and useful-skew? 3. What is meant by virtual clock definition and why do i need it? 4. Is it possible to reduce clock skew to zero 5. what are problems associated with (...)
Hi all, Please clarify me, What is capacitive loading? How does it affect slew rate? What is useful-skew mean? Din
useful skew is a concept of delaying the capturing flip-flop clock path, this approach helps in meeting setup requirement with in the launch and capture timing path. But the hold-requirement has to be met for the design.
skew is the difference in insertion delay between two registers on a given clock domain...the clock domains can be different. useful skew is the concept of borrowing time from a register in a datapath, which has positive slack, to add to the launch register, which has negative slack thereby causing the entire path to meet timing. This is (...)
hi, i came across this material in magma-da.com. lots of theoritical concepts but i think it wil useful for experienced users. rgds
we can opt timing use useful skew after CTS,and at that time,the clock tree fixed,and the useful skew is based on the fixed clock tree I right? If I'm right,I am wanding when doing CTS,can I tell the SOC-encounter that I will use the skew latter,then the software will not fix some skew that (...)