Re: polygon resistance

Of course not.

Resistance ( a 3d phenomena abstracted into a 2d problem. )

Your assumption that a "polygon" has resistance makes the assumption that
you identify the 2 ( hopefully not more ;^)
end points.

What you probably want is some sort of idealized routine to calculate an
approximate DC resistance of a rectilinear shape when
you assume that the current flow is between your two "ideal ends"

Even this is a tricky problem.

I have created path based resistor structures that were mostly rectilinear
and that computed the "number of squares" of each segment and
added (a user over-ride-able ) corner factor of ( 0.56 or 0.566 squares ...
I think this was a fab choice !? )
and then multiplied the total # of squares with the rho of the material to
get you a first (or second)
order resistance ( when added to a Fab supplied end correction factor that
was proportional to the width ... )

something like R = RHo * ( #squares ) + endfactor / WidthOfEnd1 + endfactor
/ widthofEnd2

assuming that the resistor can be broken up into rectangular sections and
corners ...
and each segment contributes Lseg/Wseg to #squares and each corner adds a
cornerfactor of 0.56square.

This was good enough in most cases ... ( unless you really needed a more
exact 3d sim run ... )

But if you require better accuracy ( or more complex structures ) either you
understand this problem much better or
you will not get the accuracy you are expecting ...


( Rant ...
Try calculating the real value of a corner in an ideal case ( say a 90
degree bent resistor with each leg being 10 times longer
than wide and then calculate the ideal corner factor. ( assume everything is
perfect ... )


Then Try rounding the corners by 1/10 of the grid and do an exact mesh
extraction that models this corner.

The accuracy of this corner factor is very suspect !!!

But I have spent many hours at different times being asked to include a very
precise cornerfactor.

Note that even though the new buzzwords at DAC of DFM and DFY are implicitly
only hooked into DSM issues,
I still faced these problems in 5u technologies .. and they had a hard time
telling me the corner rounding variations then!

.... Rant off
)

If you want accurate resistors (or matched ones ) making them rectangular
and larger than minimum helps/

-- Gerry



"mauricio" <mcontaldo@xxxxxxxxx> wrote in message
news:eb9b4633a06b41995255963e1d9bc05a@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Is there any way to get the resistance of a selected polygon or does
> anybody has a rutine for that?
> Thanks
>


.

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