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Multiple supply voltage one single power domain

mingfatty
Hi folks, i have the library cell that having two power supply, is there anyway for me to do sroute (in encounter) for this manner? or is there any other consideration i should taking care of? Many thanks in advance.
  • Vishnu Chada

    Usually in case of level shifter the primary power was connected using sroute and the scondary power was connected using nanoroute.

    for example as explained in the fetxtcmdref.pdf :

    setPGPinUseSignalRoute  <CELL> :  vddSecondary
    selectNet VDD
    setNanoRouteMode -routeSelectedNetOnly true
    globalDetailRoute

     Not sure if this is what you are looking for.

  • mingfatty
    Hi, Thanks for the reply, and it does work as you mentioned. but the problem is the power line is connected vertically to my power ring instead of horizontal as the others VDD does. do you have any advise on this. thank you very much!
  • Vishnu Chada
    Hi, How about restricting the routing layer to a single horizontal layer ? BTW is it possible to post a snapshot of the same?
  • Vishnu Chada
    BTW , how is it a problem if you connect the power line vertically ?
  • mingfatty
    Hi, Thanks for the reply, one of the simple reason why i would like my secondary power stripes to be routed horizontally it to avoid the obstruction when i am doing my power stripes later on and of course for the more tidy power planning option, I don't think is possible to restricting the routing layer to only one layer (M1) since it will need to use vertical layer when try to connect to the side ring (M2). Thank you very much for the respond. P/s: i have attached a simple routing example for your reference.
  • Vishnu Chada
    Hi, If you need a cleaner approach, you may have to define a power domain to route these scondary power pins using sroute. I did see it in one of the flows i have used but never paid attention to as it was doing what was required by the flow experts.I used the nanoroute approach to actually route SRPG AON buffer power pins for demonstration purpose. sroute -secondaryPinNet VDDS -powerDomains VddMode1 If you want to use the above you'd have to define a power domain. Secondly try restricting the top and bottom metal layers to Metal1 with the earlier mentioned nanoroute approach, it should still be able to drop VIA12 i guess.
  • mingfatty
    Hi there, i were away from sometimes. thanks for the reply. do you know where can i find information on the flow that you have mentioned since i have really no luck on my google find. many thanks in advance.
  • Vishnu Chada

    Hi,

    you may want to check the "POWER ROUTING" Section of LOWPOWER DESIGN Section in SOCE UG.

    Probably there could also be some solutions out there on support.cadence.com.

     Regards,

    Vishnu

  • mingfatty
    Hi Vishnu, Thanks so much for the advise will keep on trying on looking for the way to do this. Happy New Year to you! MF

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