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Issues with Noise SUMMARY FORM in cadence-IC5141

RFStuff

Dear All,

Can any body please tell what is the use of Include Instances & Exclude Instances options in Noise Summary form.

When I don't fill any of these these two options, I am able to see all the noise components in the Result-Disolay.

But when I add an instance in the Include Instances options ( in the hope to see only the components from that instance )  as shown in the snapshot attached in this post, nothing gets printed in the Result Display.

Can anybody please tell why this happening and how to fix it

Kind Regards,

Parents

  • A leaf instance is one of the devices that shows up in the noise summary if you didn't use this Include Instances at all. Typically that will be your primitive devices in the PDK - the MOSFETs, the resistors, the capacitors.

    This is done as a post-processing step, and it's simply listing out the individual contributing devices that you want to include, and doesn't support hierarchical blocks.

    If you'd been using IC616, and a recent enough spectre version MMSIM13.1 works - maybe earlier, I can't remember exactly when this was introduced, there's now the ability on the noise summary form to specify the "hierarchy level" (e.g. 1 for top level instances, 2 for instances below that), and there then shows up a "subckt" type in the list as well as the other model types. You can then specify a subckt instance in the include list. However, in this case it tells you the total contribution from that instance, rather than breaking it down into individual contributions from all the devices.

    Assuming the spectre version is new enough, you probably can see this in the results browser in a database called "noisesummary" - but you'd then get the waveform versus frequency rather than the spot or integrated noise (although you could always measure it at a spot frequency or integrate it in the calculator).

    The perils of using an almost 11-year old release of the software...

    Regards,

    Andrew.

Reply

  • A leaf instance is one of the devices that shows up in the noise summary if you didn't use this Include Instances at all. Typically that will be your primitive devices in the PDK - the MOSFETs, the resistors, the capacitors.

    This is done as a post-processing step, and it's simply listing out the individual contributing devices that you want to include, and doesn't support hierarchical blocks.

    If you'd been using IC616, and a recent enough spectre version MMSIM13.1 works - maybe earlier, I can't remember exactly when this was introduced, there's now the ability on the noise summary form to specify the "hierarchy level" (e.g. 1 for top level instances, 2 for instances below that), and there then shows up a "subckt" type in the list as well as the other model types. You can then specify a subckt instance in the include list. However, in this case it tells you the total contribution from that instance, rather than breaking it down into individual contributions from all the devices.

    Assuming the spectre version is new enough, you probably can see this in the results browser in a database called "noisesummary" - but you'd then get the waveform versus frequency rather than the spot or integrated noise (although you could always measure it at a spot frequency or integrate it in the calculator).

    The perils of using an almost 11-year old release of the software...

    Regards,

    Andrew.

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