Stats

  • Locked Locked
  • Replies 6
  • Subscribers 125
  • Views 16620
  • 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

question on multiple layout views to be use for 1 schematic

zeroskills

quick  question on multiple layout views to be use for 1 schematic. someone is proposing to use 2 layout views such as layout; layoutv2 for 1 schematic. i think the reasoning was like this, he wanted a 2 versions of layout with one schematic like the example below...

cell: opamp

- schematic 

- layout - original layout

- layoutv2 - exact copy of the original layout, but caps have been modified to fit a specific spot in chip

----> the cell opamp have 1 schematic but have 2 layout view, layout is used on the left side of the chip and layoutv2 is used on the right side of the chip.

i asked, why not just have another version of the circuit/schematic (opamp --> opamp_v2), with 1 schematic and 1 layout view. so my reasoning was like this:

 

cell: opamp

- schematic 

- layout - original layout

cell: opamp_v2

- schematic 

- layout - exact copy of the original layout, but caps have been modified to fit a specific spot in chip

----> opamp layout is used in left side and opamp_v2 is used on right side.

but he insist to just have 1 version of the circuit schematic since if he did have another version it would be just the same. also i think he doesn't want to change another version of the same circuit if he have changes, like his changing the same circuit twice.

so is it possible to have 2 layout views of the same schematic? since i've been doing layout, i never have taped out any cell or citcuit that have a different layout view or shcamtic view, it's always been layout and schematic for 1 cell and that's it, and not for example, 1 cell then layout2, schematic.

  • Yes. Read up on 'Configure Physical Hierarchy' (CPH) in Chapter 4 of the Virtuoso Layout Editor XL User Guide: http://sourcelink.cadence.com/docs/files/Release_Info/Docs/vxlhelp/vxlhelp6.1.3/chap4.html

    Andrew.

  • And if using IC5141, you can use the lxUseCell property to tell a particular instance of opamp in the parent schematic that it should use one variant or the other.

    If you're not using Layout XL, then it doesn't matter of course - you can do what you want!

    Regards,

    Andrew.

  • we are using vxl, an i know that if you make a copy of the original layout, either by copy cell or save as, the copied cell would still retain the info of the orginal cell. so if i copied opamp layout and save it as layoutv2,  layoutv2 would be ther same as the copied layout.

    so it's possible or ok to use 2 layout views for 1 schematic, as long as you configure it properly. would there beany problem for tapeout check or layout hierarchy, like from my example, everything is layout except for opamp cell having layout and layoutv2.

    i'm used to having schematic and layout content per cell, and if i wanted another veriosn of that cell i would call it opamp_v2 with layout and schematic content instead of opamp cell having schematic, layout and layoutv2.

    but is it adviceable to have 2 layout views in 1 circuit/schematic? 

    by the way, thanks for the advice guys.

  • I don't see any problem with doing this - having multiple layout views per cell. It's frequently done. Only if you have some specific check implemented at your company to ensure all layouts are in a view called "layout", but that would be fairly unusual.

    I have lots of examples in my databases that I use to demo the software where I do this kind of thing...

    Regards,

    Andrew.

  • yes, even me have several layout views layout 1,2,3 etc. for temp layout or saves.i usually do that to play around and think over other several version, but when tapeout comes, i only use layout as the final.

    i've been doing layout in a long time but never have I encoutered having this kind of situation, having 2 layout view for 1 schematic. it's always 1 schematic per layout and if there's another version of the layout of the same schematic, they would just create another schematic for that 2nd version of the layout, even if it's the same as the1st one.

     thanks for the inputs. by the way, have anyone of you experienced taping out projects having a layout view other than "layout"? i mean, having your final chip or sub-cells called other tnha layout?, like it's layout_final, or layout_clean etc...

  • Well, you could create a duplicate schematic, but it's completely unnecessary. One of the whole points of having a lib/cell/view structure is to allow you to vary all three, both in terms of creation and instantiation.

    Regards,

    Andrew.

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.