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52 Threads found on edaboard.com: Max Transition
Hi, I am a graduate student who is new to Prime Time tcl coding. I would like to know if there is a way to know the cells that violate maximum capacitance constraint, such that I can swap cells manually. Much appreciated.
Hi, I think it doesn't solve the problem but it reduces the error to max 1 LSB. Klaus
Hi guys, I am trying to place and route a digital design. During the pre place time analysis, the software (Innovus) issues a warning alerting that the slew rate of the several cells is out of bounds with regard to the value specified in timing lib. The weird thing is that I am specifying a maximum slew rate (max transition time) of (...)
As for the min pulse violations, are they relevant for clocks only or for glue logic as well? - - - Updated - - - How can I fix the max Capacitance and max FanOut violations?
Hi frinds.. after post Route fixing setup/hold still i'm seeing some transition violation and fanout violations how to fix them , what are the violations are real....? here are the Fanoutviolation info... ---------------------------------------- *info: there are 121 max fanout load violations in the design. *info: 113 violations are real
Thank you dick_freebird! I tried to earn delay of all inpus to outputs from cosmosScope/wave viewer delay func and max of them is very near to the result in .lis file (in spite of negative values),just with 0.2 pico difference. Could you plz Write an example about clip func, I Couldnot find that's difinition in manual or internet! Meantime I foun
Impedance control gives best control of ringing due to transient CISS during transition. THe ratio of source to switch to load impedance has a penalty of rising CISS with lower RdsOn. I prefer to choose a ratio of 50:1 max from driver to switch impedance. Then asymetry is another choice due to shoot thru, so lower impedance turn off and higher tu
Thank you wesleytaylor. I want to know about max.transition, max. Capacitance and max. Fanout DRCs. What will happen to the design if these are not met?
max transition is the transition for the highest load which is characterized in the library. it is associated with the output pin of the cell. this tells you that the max transition that is allowed at the pin. it has nothing to do with the frequency. the output transition will depend on the (...)
The max transition limit if specified over the lib limit, will be usually lesser than the lib limit. Even if the limit set is higher, the STA tools will pick up the worst case and perform the analysis.
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 and fix it?? Am I interpreting it correctly? Now if we go
The max transition reported by CTS could be waived if the max transition defined for CTS is below or equal to the Std cell max transition. If you want to "relax" CTS, you could used the max transition defined by the std cell library, if you want to be more (...)
hi, first of them all of this parameter could be changed by script: specifyClockTree -update { AutoCTSRootPin maxDelay 10ns} and "maxDelay", could be replaced for "SinkmaxTran", "BufmaxTran", "Obstruction", .... max/min delay: latency constraint of the clock tree. Sink (...)
Hello Can anybody please explain the difference between set_max_transition and set_input_transition constraints?
My opinion need to fix all clock and data path. One point is if transition is very close to lib range say max trans on data cell inside lib is 1 ns and you are at 1050 ps. In this case if timing path is met with decent margin then probably you can wave it. But it is hard to meet above criterion for too many paths so easier would be fix
DRV is the max capacitance/fanout/transition violations.
I suppose the max_tran limit is coming from the values specified in the .lib. So even though the output load looks small, you need to check what is the max value specified in the lib and perhaps your load exceeds this one, hence the violation.
What do you mean equal? transition, is the time needed to the signal to goes to zero to one or one to zero. Load, is the capacitance seems by the output pin of the std cell. Both are used in the liberty to characterize the timing, and the maximum constraint should not be violated, because the timing will be extrapolate, and we don't know if the val
Just want to know the opinion of the forum. Is it preferred to use exactly the same set of constraints for both synthesis using DC, and STA using PrimeTime? Does the synthesis tool use the false path specifications, or max transition constraints? Or can we use a simpler constraint file to do synthesis, and then use a more elaborate constraint
... fT/10 is easy to achieve for a GBW of an amplifier. What is your idea of this fT ~~GBW relationship?? John: yeah, I think it's quite a good estimation, at least for an amp with max. 2 stages.
First you need to simulate the full input sweep, picking off the actual input voltage value at each code transition and subtracting from it the ideal transition value. Store all of these (0 - 2^N-1) and use either Ocean code or an external tool to process the individual bit errors to get DNL (max()) and INL (I forget, something like (...)
Hi Ravieja, If you look at the .lib models ( NLDM Library ), the delay depends on Input transition & Output Capacitance. What will happen if the input transition/output capacitance goes beyond the characterization limits? The tool extrapolates the delay value, which is not a perfect. People usually constraint the design with max Tan (...)
max fanout limit is defined to avoid max. cap and max. transition violations as far as you meeting them, you can ignore max. fanout violations. yup agree. max fanout is used to control number of loads driven by one output, however the amount of load that can be driven by an output is (...)
Hi all, How synthesis people will desire the max transition value for design?? How to calculate that max transition for design?? Thanks in advance, Regards, Nantha
Actually, for each design(EDA), We often set the DRC rules, ie. max_transition max_fanout max_capacitance... You can find "max transition" "max_fanout" ... in a library (.lib synopsys format) If you dont set a "max transition" in (...)
Hi All, On what basis max tran rule is defined? Is it same for all the nets? How is it different and why ? Should we fix all tran violations in the design? Regards Tachyons
hi guys , i have an elementary question about transistor , how can i know the bandwidth of the transistor ? in the data sheet i just found "transition frequency" which didn't have a max value , or it is just the inverse of the "storage delay time" tsd?
hi my opinion is you sample the transition1 to 0 ie. you get value in var when the pin goes from 1 to 0, this will wait for the transition for max of 655 ms. hope this helps
If the transition viol goes beyond what the timing library is characterized at, timing analysis tools have to extrapolate the delay curve upon the delay calculation, which makes the timing inaccurate. You have to keep it at least within the max transition defined in the timing library.
Hi, I wanted to know what parameters decide max capacitance, max transition and max fanout constraints in sdc? what decides to what values we should set these values to?
Refer to the I2C bus specification (see link below) for details on max capacitance for each pin (SCA or SDA), max bus capacitance, min width of clock pulse etc. etc .. Take into account that I2C bus has specified max rise and fall times of ANY transition that have to be executed by ANY device connected to the bus .. In (...)
how to understand the gain error of adc? i think, it is the change of slope of actual transition curve relative to ideal transition curve. but corresponding to the output code, what does it mean? for example. for a 12 bit adc, the ideal max output code is 4095, but if the actual max output code is 3957, while the min (...)
During the characterization of a 90nm library, I'm plotting gm = f(vgs) and gm reaches to a max and then decrease. Why gm reaches a max and then decrease? Thanks, Joel.
One more reason of fixing max transition violation is that bigger transition will result in bigger DC power consumption
Depends on the logic you can ignore those violations but some times it matters... For example you have some combo logic between two different blocks and you are assuming that the logic is going to take time less than 1 clk cycle.. but for the worst case it may takes more than that and this reports to max transviolations... this can be ignored i
Hi , i am generating the Standard cell library(Synopsys Lib format) along with the standard cell design. I have to calculate the max_capacitance Attribute in the library. The max_cap attribute defines the maximum total capacitive load that an outputpin can drive. So i have calculate the max load. Bottle neck is, if (...)
Hi Sir/Madam How do i know what should be the right number for the max transition that I should set for my design? For example: Library = tsmc 250nm Speed = 400kHz. Thanks in advance for your help.
Hi, I' m getting a bit confused, in logic synthesis how do we fix the violated design rule constraint which are max capacitance, max transition and max fanout?
why do we have max gain in transition region in case of cmos inverter?
U are talking about the Design Rule Violations which are max transition( slew violation), max Fanout Violation and the last one is the max Cap violation which is the load violation... And this occurs if ur design not meeting the u have to make it tight by adding buffers in the appropriate position by seeing all these (...)
Hi, max transition violation is b'caz of more load. To solve that do cloning or insert the high drive strength buffer in that path. Prithivi.
When you say faster you have to mention the ft (unity current gain frequency ) & fmax (unity power gain frequency) you can see that ft & fmax of BJT are larger than ft & fmax of MOS best regards, Rania
The max violation may cause large short circuit power since both PMOS and NMOS would be on for a longer period of time.
setup violation occures when the delay of the logic between two FFs (having the same clock) is so large that the logic output is not ready on the input of the second FF before the next clock transition and this FF may sample the past value instead of sampling the current one. So if there is no delay there will be no fear of setup violations , which
As the name says delay cells provide more delays in the order of ns in some libraries. functionality is same as buffer. These are basically used for hold fixing if the violations are more. Please guard band this cell with normal buffer as this might give a transition or max cap violation if this driving a high drive strength cell. hope this he
Currently I encounter big problem for kind of transition pattern simulation w/ sdf. use 1000 patterns. In max condition, pattern simulation is clean w/o mismatches. but in MIN condition, pattern simulation encounter huge number of mismatches, but limit to like 14 pattern out of 1000 patterns failed. for ex. simulation value is 1, but expe
max skew means the difference between the clock arrive the cloest and furthest register. transition time: decided by the drive capacitance of the cell. Both them can impact the performance of the chip such as the highest working frequency
Dear Wany, You will always find a glitch at every transition. But how major is it depends on where the code is changing. For example, in a 4 bit DAC, you will see a max glitch where there is a transition of code from 0111 to 1000. But you will also notice glitches during the 0011 to 0100 transition and so on. The reason (...)
HI,all How to decide the set_load and set_driving_cell In dc script. with many thanks. Johnny set_load says the max capacitance ur block will be driving. set_driving_cell says the max transition on input ports. You shud tell these values based on the situations on which ur chip going to work at.
Hi , I would like to know the causes for the max transition time violation ??? I heard that two reasons may lead to this violation 1) input delay of the pin is very high ( more than ) the set value in libary 2) do the wire length that leads to the delay. I would like to know in each case how design compi