Stats

  • Locked Locked
  • Replies 2
  • Subscribers 125
  • Views 11199
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Cadence XFAB layout question

Farnaz

Hi,

My question is regard to layout design in Cadence XFAB018.

I want to use a photodiode (dphoa) layout that exists in this technology library. But the problem is that the minimum size of the diode is 10u by 10 u, which is not desired for my project.

I decided to remove some unnecessary layers and it works. The DRC and LVS tests were passed. But in this case, the size is still more than what I want.

In the next step, I decided to minimize some layers of the photodiode layout, but I gave some errors which said the PHODEF layer without NIMP is not allowed.

It should be mentioned that the NIMP layer does not exist in the original photodiode layout. It is worth mentioning that when I increase the size, I do not have the error.

the following picture is a part of the technology datasheet which may clarify what I mean.

My questions are, why with increasing the size of layers in layout, the DRC recognizes the layout as dphoa photodiode while by decreasing the layers it seems that the DRC is not recognized the layout as dphoa?

How should I solve the problem?

I hope I could convey my questions.

Best regards,

  • As I said before, this technology comes from X-Fab (not Cadence), so it's not "Cadence XFAB018". You would be better off asking X-Fab about technology-specific questions - although maybe you'll find somebody here with experience of the technology who is able to answer.

    I would be wary of dropping below the minimum size because there may well be technology reasons that a smaller than minimum size device is not allowed (it may not be particularly effective as a photodiode, for example, due to not having enough area to capture the light!). Note that this is just a guess rather than specific knowledge of the technology - but normally there are good reasons for minimum sizes!

    Andrew

  • In addition to Andrew's comments, device recognition often involves layers and size checks. if a minimum size is required, the shape/object may either be considered as invalid if it is smaller than required, or 'disappears' if a size-down-then-up is performed in the rule deck. As a result, the shape or processed shape will not become part of the derived device recognition layer. Therefore, the the device will not be correctly recognized.

    Guangjun

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.