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Inherited terminal

Vishesh Gupta

Hi,

I was working on a new PDK and saw them use: "sub!*" for their pmos. I searched on the internet and learned that it is a inherited terminal of substrate.

I am not familiar with inherited terminals. Can someone please help with the following:

1) While running the simulation that uses pmos with an inherited terminal ("sub!*"), is giving voltage to the inherited terminal necessary? If yes, how can we do that in the schematic?

2) I am trying to run LVS of a schematic with "sub!*" inherited terminal. When I did : Connectivity->Generate->All from source, no sub! terminal was generated automatically. The LVS report has the following error:

I would really appreciate anyone's help!

 

Thanks and Regards,

Vishesh

Parents

  • Vishesh,

    I suggest you read up on inherited connections - this video is probably a good starting point: Introduction to Inherited Connections

    The idea is that you can have (say) a MOS device with 3 pins on the symbol, but the stopping view (e.g. the spectre, auCdl view etc) have a 4th pin (e.g. the B pin) with a netExpression on the terminal. This defines the name of the property and default net that this terminal will be given (e.g. sub!) if the property is not specified. This can be overridden by adding a netSet property on the instance or somewhere higher in the hierarchy to define which net that inherited terminal will be connected.

    Once netlisted (for simulation or LVS), it's as if there were 4 terminals on the instance in the first place. You can connect a voltage to that 4th terminal simply by connecting a voltage source to the same net to which the 4th terminal is set (either by property or its default). LVS should also work fine - it looks in this case as if the issue is that the layout only has 3 terminals recognised (hard to say without more detail).

    Perhaps you should contact customer support - it would be easier to understand your issue if an application engineer can talk to you and see what you've tried.

    Andrew

  • in reply to Andrew Beckett

    There is also a Rapid Adoption Kit "Basics of Inherited Connections" at support.cadence.com/.../articleattachmentportal

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