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# Analyzing a Circuit with "Worst Case" Method

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#### Vauxdvihl

##### Member level 5
Hi friends,

i have to analyze my circuit with a "worst Case" Method.
This circuit contains a lot of resistor's, cap's and transtistors
(also CAN and LIN device.........because of Automotive) !

Can please somebody help me with giving me tips where to find stuff
about that and how to handle/calculate that.

All help is very welcome (like pdf's, I-Net Sides, files etc etc etc ).

Thank you very much for your help

Regards

As a start, things like this:
Hot temperature, all component tolerances in one direction.
Hot Temperature, all component tolerances in the other direction.
Cold temp, etc.
Cold temp, etc.

Since you wan't worse case, you don't want to use Gaussian distribution on your tolerances.

Maybe there is somebody who has some some papers for me ??
Papers (or I-NEt Sides, Doc's from Studys) who can explain me this method ???

Thank you very much

Regards

Worst case design?

It means that all the tolerence of all components have to be calculated.
What papers would describe this ?
You have to examine and check all the circuit components and find
the datasheets. Then keyin all extreme-value of all components.

And re-examine the dsign results and see if design goal is met again.

You should have the following worst cases :
- min temperature / min voltage supply / min process
- max temperature / min voltage supply / min process
- min temperature / max voltage supply / min process
- max temperature / max voltage supply / min process
- min temperature / min voltage supply / max process
- max temperature / min voltage supply / max process
- min temperature / max voltage supply / max process
- max temperature / max voltage supply / max process
But for analog CMOS processes you also have the case:
- NMOSmin/PMOSfast
- NMOSmax/PMOSmin
- Rmin/Rmax
- Cmin/Cmax

Well, if you use HSPICE or ELDO, use .alter command to run those cases, and .measure to simplify the analysis. The ELDO .defwave is also useful.

If your simulation is too long, try to gather the slow cases and the fast cases.

OkGuy?

Thank you very much guys !!

@mild-seven
This papers descibes this !
http://www.designandevaluation.com/
WORST CASE CIRCUIT ANALYSIS HANDBOOKS
A TWO VOLUME SET OF WCCA HANDBOOKS

VOLUME 1 - An Introduction to Worst Case Circuit Analysis
VOLUME 2 - Worst Case Circuit Design and Analysis Guidelines

And i think there are a few more sources avaiable.....

Regards

I cannot open that site.
Is there any mistake in your spelling ?

Okguy?

@Okguy

I really do not know where the problem is ???

It works very fine !

I've got another one for you...check this out (a really got example how describes the WCCA analyses....!!

Maybe somebody knows other good sites (or Ebooks)

Regards

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