Extracting device (photodiode) using Assura

[leoshelby]

I have designed a custom diode in cadence virtuoso (layoutL). For LVS, we need a schematic of the photodiode, which is not available in the tsmc .18 pdk. But it did pass the DRC. Now, I want to extract the device (not only parasitics) from the layout and make a schematic out of it.

I tried extract from verify, but I am not able to find the Divarule file in the pdk. Please guide me.

Thanks

 

[guntherleet]

If it custom, generate a schematic view for this cell and have the Layout view 'know' that this is his master

 

[leoshelby]

If it custom, generate a schematic view for this cell and have the Layout view 'know' that this is his master

Thanks for the reply. How to generate a schematic view from the layout? Can you please elaborate on "have the Layout view know that this is his master "?

Thanks.

 

[dick_freebird]

You don't need a schematic, this diode is a new primitive. You need
a symbol for it and one or more of the aux views that your extract
and LVS activities need to see.

Then wire some pins to the placed cell, make a similar schematic
and run LVS, to show it works in a higher level(not very) assembly.

 

[leoshelby]

Thanks for the response. Sorry for the late reply, I was busy with another deadline.


I understood we want a symbol view. Can you please elaborate on aux views and how to create symbol and aux views?

Then wire some pins to the placed cell, make a similar schematic

Can you please explain in a bit of detail how to make a similar schematic (as the same device (photodiode) is not available in the pdk )? If you have any documentation or tutorial, kindly share it.

Thank You.

 

[D.A.(Tony)Stewart]

You can create any custom diode and use as a photodiode if you can define each variable. Or simply choose a number like mA/mW @ nm wavelength . Compare with 0.5 mA/mW.

 

[dick_freebird]

Easiest would be to take one of the diodes that -is- supported,
copy its cell & underlying views to your own custom library
(unless you have write access to the PDK installation, which is
unlikely unless you are your own sysadmin). It's likely that the
photodiode is one of the usual junction combos plus a little
art. So pick the closest.

There's your symbol, for the name-changing. You can go figure
out netlisting re-pointing and so on, and get to where a placed
"photodiode" will run right in simulation.

Layout extraction probably means editing extract rules, and that
in turn may need layout features added or touched up (like if
devices are recognized by fancy logic and layers, not a simple
text tag). Probably have to add the rules for the photodiode,
again by copy-and-modify.

But before you get started down that road you might place a
layout instance and see what, if anything, extracts. That would
be an Easy Button. At least, relative to starting from nothing or
from something that's way unlike.

 

[leoshelby]

Thanks for the reply!!

After the completion of the photodiode layout, I added a dummy diode layer to match the schematic diode of similar diode junctions. The LvS is passed, but during post-layout simulations, the I-V curve is the same as that of the schematic normal diode (Not a photodiode).

Can anyone guide me in this? Is this the correct method?

Thanks