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90 Threads found on edaboard.com: Setup And Hold Check
lots of corners. check the foundry documentation. you probably have some lots of corners: setup ones, hold ones, process variation, temperature, etc.
At first sight, it looks like a trivial setup or hold time violation. Did you check with setting d earlier and holding it longer?
check this link Fixing setup & hold Violations
Hi All, i've a confusion why worst case report is considered as the Max delay violation(setup violation) and Best case report as Min delay(hold violations). and why we always calculate the hold violations at the launching flop. thanks in advance, Arjun
So before looking to the setup/hold time report, you must have the trans/cap violations clean or so small than the impact is reduce. So rca - Lets consider PT - so all you are saying is first of all check for Max trans/cap, fix it, and then you check setup/hold (...)
Hi Esakki raja , Follow the below links. Thanks, Alam
Will setup and hold time for D_latch and D_FF will be same if they are fabricated via same technology? In multi-clock design, In case of FF we wait for next rising/falling edge and check the setup time at that particular instant While in latch we dosent wait for next (...)
Hello sir. I am reading about lockup latches. Sir how exactly lockup cell removes the hold violation? and sir why we do check setup analysis in next clock and not at the same clock? If first clock for destination clock laging the source clock and during that time if data can settle then what (...)
Suppose a clock is generated from another clock and hence in the synthesis SDC we provided the create generated clock and also the create clock to create the generated clock and the source clock respectively? Is there any necessity to provide in the synthesis SDC when should setup and hold (...)
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.
To check setup : The setup multiplier Can be N. The launch will happen at 0th clock cycle and setup capture will happen at Nth clock cycle. To check zero cycle hold check : set_multicycle_path -hold 1 The rule is: (...)
hello every one... can anybody clearly explain about checking of setup and hold violations in clock gating path
May not be required.Just check the setup and hold margins from the datasheet..
Hai all, What is Recovery check,Removal check? please could u tell me Eqs for Recovery check,Removal check like setup time and hold time ? Thank u............
you can use data_check command in primetime to check signals which are not in the setup and hold format in the library. The data check commands are designed for the purposes of timing checks between handshaking systems.
It will depend upon the magnitude of your tran violations, if magnitude is above the library limits definitely it needs to be fixed, as your library is not characterized for such a transition, and the delay value calculated by tool corresponding to such transition may be inaccurate. So, actually you might be violating setup but shown non violated b
Hi All, Here is a question from my last interview: GIVEN: Blocks A, B, and C (see the picture below - click on it in order to zoom it in) Block 'B' timing requirements: setup Time: 4nSec hold Time: 2nSec Clock Period: 20nS Block 'C' timing requirements: setup Time: 3nSec hold Time: 1nSec (...)
1): It seems there is a command called: "set_clock_gating_check". and by default, DC/PT will check the clock gating celling setup/hold requirement, which are all set to "0". 2): For scenarios, I think it's PVT+chip working mode (such as function mode, scan mode, MBIST mode)
The worst library is usually used during the synthesis phase to meet the setup requirement. During the PR, in the "basic" mode, you define the worst library set to check the setup and the best library set to check the hold time. Now the tool have the MMMC feature, means (...)
Need little bit explanation on Why we fix setup Violations and then fix hold violations
While fixing setup, usually, we fix for different corners. fixing dominant corner would have helped other corners too.. What is the point, we consider for fixing other corners as well??
Hi During preCTS the clock is considered to be am ideal clock and hence the hold violation that occurs due to skew cannot happen(as it is ideal). Hence, we go only for setup check during preCTS stage. Once CTS is done, ideal clocks are replaced by real clocks and hence skew appear which may lead to (...)
setup time is the minimum amount of time data must be stable before arriving active edge of clock. If skew is positive clock edge arrives late. So it is helps in meeting setup time requirement. hold time is the minimum amount of time data must be stable after arriving active edge of clock. If skew is negative clock edge reaches early. So it (...)
Is addition of buffer causing setup violation on the exact path violating in hold. Try to upsize the cells in setup path to high drive strength cells. Derating could could also be a factor. check for some hold specific cells being used in the design and convert to normal cell. Hope this (...)
DRC might check these race conditions. We had to check race conditions manually in the old days or ensure everything had ample setup time using a the right clock phase to latch data or use asynchronous set, reset after read data.
Hi, I am trying to use timing debug feature in soc encounter. When we click on the timing debug from the timing menu in the soc encounter, it will automatically display a new window with setup timing check. I want to analyze by viewing the path histogram of hold time but dont know how to do that after search in the soc user guide (...)
Hi all...., Why setup time analysis is done during PLACEMENT why not hold along with setup time during placement? I know the answer but not exactly can you plz clarify it....., What i know is the setup time is calculated at next edge and when the hold is done (...)
Well it depend on a lot of things like the source of clock, layout, components etc. Introducing 20% uncertainty in clock may cause setup and hold time violations in circuit.
Hi All, As for the setup and hold checks, should I run the PT tool twice each time for either setup Or hold check? If the tool is able to read slow and fast SDF and libs together, why not running it only once for all kind of the (...)
1.How can I check the setup time and hold time for a timing path. the first FF is positive edge trigger, but the end FF is negative edge trigger one. 2. The hold time is still depended by clock frequency like normal? Thanks
setup is check at each step from synthesis to sta. hold time after the clock tree.
in this case, you can check setup/hold time using normal timing analysis. if Q1 changes 1 clk1 cycles before clk2, then the signal must be stable and meet the setup requirement of a single clk1 period. if Q1 can change on the clk1/clk2 edge, then hold time will be based on this. now, if Q (...)
when RTL is written, They would assume that , data will be passed between the registers, with respect to clock edges, i,e one edge launches data on q pin of ff then by next edge only the next ff should capure/read it. setup time check makes sure that, when next clk edge reaches the ff2, data will be ready at the ff d pin, if its not ready befo
The -min lines are for min delay analysis (for hold check), and -max lines for max delay (setup check). Usually we are using the worst corner library (SS process, high temp, low voltage) for setup check, and the best corner library (FF process, low temp, (...)
the important topics are the setup time and hold time violation ,tweaks for fixing this violation.and cover all front end steps(i.g. synthesis,verification ,STA)
What is clock gating check? Why is it requited? How does it check the setup and hold violation?
Where did you get these lines? setup is checked at the next rising edge (for FF triggered by rise edge) and hold is checked at the same edge , not the falling edge. Please do double check.
MCMM is only multi corner & Multi mode, that's means, you indicate to the tool, all the combination (rc-library) where you want the tool check the setup and the hold time. OCV (On Chip Variation), just add more timing varation over the design, for all the MCMM, it it generally apply after CTS, to fix the remaining (...)
I am not sure if you want to set uncertainty for setup or hold check. Ex below is for setup. Change the -setup to -hold if you want to setup uncertainty values for hold. set_clock_uncertainty -setup 0.800 Btw, you don't have to set jitter (...)
Hi niladri.s.debnath! R u sure ur critical path is not a false path? To my knowledge, we dont need any particular cmd for setup time check. VCS will do it automatically if the sdf is annotated correctlly.
On the edge at one cycle before the setup edge by default.
It would be nice if you send your circuit. In theory setup/hold should not depend on output load because it's mainly defined by switch (if you use switches).
If you dont say anything in your timing constraint, the hold check is normally assumed one clock cycle before setup. Therefore, hold is checked at the n-1 clock edge if the path is n cycles long. You can specify when the hold check occurs in your multi-cycle constraint. (...)
We use slow libraries for setup time and fast libraries for hold time voilation check. Why it os so? setup: flop_launch_clk_edge->combo_logic_delay->flop_capture_clk_edge. setup is defined as the amount of time required for the signal to be valid before the capture clock edge. This is (...)
I'm not familiar with vcs. But i would probably **** into the standard cell that used, and comment out $setup, $hold etc lines within specify block of Flop models under concern. - phixcoco
Dear all, I have one question about the timing, please help me !! We know the setup time check at worst case condition. Is it possible the timing is met at worst-case condition, but violate at best-case condition ? and why? Thanks all and have a nice day. ^^
you will find this lovely timing diagram, in any tool documentation or on the web, google is your friend!
question to experts: does all known providers of standard cell libraries during a silicon verification check setup/hold timing of flip-flops, and does their test report incorporates result of this check? Another question: what is most reliable method to implement (...)
What is the use of having Maximum Transition Time & Maximum Cap check rules?. I think these are all again similar to setup & hold Violation check. People may share their views & help for better understanding.
Hi, As a verification engineer, if a setup or a hold violation is found out during GLS process, what is it that the verification engineer should do? Thanks.