Dear all,
Can someone explain TT,SS,FF,FS,FS in detail, respectively?
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Dear all,
Can someone explain TT,SS,FF,FS,FS in detail, respectively?
T: TYPICAL
S: SLOW
F: FAST
Actually in real life what we simulate in the simulators we don't get exactly that in the physical design.So as every thing is probabilistic you have to ensure that the chipyou fabricate should work in all process corners. .They are what you have listed.Now suppose you have a speed spec.So if the functionality is achieved in all specs then u have to simulate in Slow-Slow corner to figure out the worst case speed.Similarly for power spec u simulate in FF corner as in that corner the Current is maximum as the transistors have low Vt there.
Hi,
Fast means operation fastly which reasons from thin gate oxide or other
fabrication variation. vice verse.
best regards
fxxjssc
TT - Typical NMOS, Typical PMOS
S - slow
F - fast
SS/TT/FF/SF/FS make chip corners, which directly determines your yield
MOS corner
FF:Fast Fast
SS:Slow Slow
FS:Fast Slow
SF:Slow Fast
these are mos cornersQuote:
Originally Posted by Anachip
TT: typical typical
FF:Fast nmos Fast pmos
SS:Slow nmos Slow pmos
FS:Fast nmos Slow pmos
SF:Slow nmos Fast pmos
All the corners have to be taken care for the better yeild.
my finding most of the time SS, 125C, low supply voltage(especially for feedback less ckt) is the most worst corner
How about the monte carlo simulation...... what is the different compare to corner simulation...... both are predicting the yield if I not mistaken......Quote:
Originally Posted by electronrancher
Quote:
Originally Posted by pbs681
The difference in Monte Carlo analysis compared to Corner Analysis is the number of simulation you run to confirm the yield. In Monte Carlo analysis, you have to run a few hundred to thousand simulation in order to have more number of combination of processes and mismatches, whereby in Corner Analysis, you just need to run 5 simulation for SS,FF,FS,SF,TT. In this 5 simulation, what ever possibilities of process distribution is all ready taken into consideration.
Hope this helps you.
Quote:
Originally Posted by shaq
Actually what i know Fast in the sense is carrying higher currents than normal...
it is the variation of the process in such a way it carries higher current than typical.
and slow is vice versa
Thanks.....Quote:
Originally Posted by suria3
Anyway, since we already covered all the possibbilities of the process variation by running 5 corners simulation, why do we still need to run monte carlo. If we pass 5 corners requirement, then our chip should functioning within the specification right..... need your advise
Added after 9 minutes:
You can check the model file under section device...... it has all the parameters name that varies and how they define the variation...Quote:
Originally Posted by shaq
This is true. Corner analysis does include all the process variation possiblities, whereby the Monte Carto Analysis will do both the process and mismatch analysis. So, even though your design pass the Corner Analysis for all the 5 cases, it is still a necessary for you to run Mismatch analysis in Monte Carlo to confirm on the mismatch matter for your design to behave. ThanksQuote:
Originally Posted by rajanarender_suram
[/quote]This is true. Corner analysis does include all the process variation possiblities, whereby the Monte Carto Analysis will do both the process and mismatch analysis. So, even though your design pass the Corner Analysis for all the 5 cases, it is still a necessary for you to run Mismatch analysis in Monte Carlo to confirm on the mismatch matter for your design to behave. Thanks[/quote]
I agree to suria...after even corner analysis mismatch analysis need to be performed for statistical variation of performance parameters of the designed block arising from device-,ismatch.....definitely the "Monte Carlo Method" does this.... some times it is time taking and not affordable....a preactical way of device mismatch simulation is given in the following link.....it is a commonly used method and not applicable for huge blocks...but good for blocks having low transistor count.....
http://www.edaboard.com/viewtopic.ph...light=sankudey
hope would help u....
sankudey
This is true. Corner analysis does include all the process variation possiblities, whereby the Monte Carto Analysis will do both the process and mismatch analysis. So, even though your design pass the Corner Analysis for all the 5 cases, it is still a necessary for you to run Mismatch analysis in Monte Carlo to confirm on the mismatch matter for your design to behave. Thanks[/quote]
I agree to suria...after even corner analysis mismatch analysis need to be performed for statistical variation of performance parameters of the designed block arising from device-,ismatch.....definitely the "Monte Carlo Method" does this.... some times it is time taking and not affordable....a preactical way of device mismatch simulation is given in the following link.....it is a commonly used method and not applicable for huge blocks...but good for blocks having low transistor count.....
h**p://www.edaboard.com/viewtopic.php?t=154335&highlight=sankudey
hope would help u....
sankudey[/quote]
Thanks everybody.... now I understand
thast means the technology's envirnoment
those are just different corners name that is ofen seen in model files
FAST MOS : Smaller Vth
SLOW MOS : larger Vth
u have to check the ss ( slow slow corner) which is a real culprit in most of time ..