• Skip to main content
  • Skip to search
  • Skip to footer
Cadence Home
  • This search text may be transcribed, used, stored, or accessed by our third-party service providers per our Cookie Policy and Privacy Policy.

  1. Community Forums
  2. Custom IC Design
  3. To have inverter symbol without VDD and GND as well as successful...

Stats

  • Locked Locked
  • Replies 1
  • Subscribers 125
  • Views 16730
  • 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

To have inverter symbol without VDD and GND as well as successful post layout simulation

gentle016
gentle016 over 12 years ago

 I am not using vdd and gnd as pins in schematic(instead using instances from analoglib).Now after layout is done and config view is done,the post layout simulation is not considering the vdd and gnd(therefore shows different output waveform).If I use the vdd and gnd pins(in scematic) than i get the correct waveform, however this makes inverter symbol with four legs. 

  • inv_schem.png
  • View
  • Hide
  • Cancel
Parents
  • Andrew Beckett
    Andrew Beckett over 12 years ago

    The pins on the layout could have global names, and then it should work. However, the best solution would be to use inherited connections. If you create pins on your schematic for vdd  and vss using a "netExpr" (defaulting to (say) vdd! and vss!), controlled by a properties vdd and vss respectively, and also use Layout XL to generate the layout - you'll have similar pins on the layout, and also on any resulting extracted view.

    There's then no need to have the pins on the symbol - you can keep that having just the input and output pins. You'll also then have the ability to reuse the inverter in various supply domains by adding netSet properties at a higher level to override the values of the supplies.

    This is well covered in the documentation - probably search for "inherited connections" or "netExpr" or something like that.

    Andrew.

    • Cancel
    • Vote Up 0 Vote Down
    • Cancel
Reply
  • Andrew Beckett
    Andrew Beckett over 12 years ago

    The pins on the layout could have global names, and then it should work. However, the best solution would be to use inherited connections. If you create pins on your schematic for vdd  and vss using a "netExpr" (defaulting to (say) vdd! and vss!), controlled by a properties vdd and vss respectively, and also use Layout XL to generate the layout - you'll have similar pins on the layout, and also on any resulting extracted view.

    There's then no need to have the pins on the symbol - you can keep that having just the input and output pins. You'll also then have the ability to reuse the inverter in various supply domains by adding netSet properties at a higher level to override the values of the supplies.

    This is well covered in the documentation - probably search for "inherited connections" or "netExpr" or something like that.

    Andrew.

    • Cancel
    • Vote Up 0 Vote Down
    • Cancel
Children
No Data

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.

© 2025 Cadence Design Systems, Inc. All Rights Reserved.

  • Terms of Use
  • Privacy
  • Cookie Policy
  • US Trademarks
  • Do Not Sell or Share My Personal Information