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Contents of hbnoise_xf results directory

Michele Ancis

Hi, from within Virtuoso 6.1.6 , MMSIM 13.1 ISR10

I am performing an hbnoise analysis on top of a {single|double}tone HB.

The simulation creates a series of directories under the psf database:

hb_td

hb_fd

hb_fi

hbnoise_xf

hbnoise

...

I am interested in the results contained in *hbnoise_xf*, as I am assuming that this directory contains the results, frequency by frequency, of the transfer functions from different points/devices in the netlist to the designated output.

Strangely enough, while the other mentioned directories contain results for each and every node in the netlist (I did a "save all" just to see whether this was the issue), the hbnoise_xf directory contains what seems to me to be a /random/ sample of the instances and devices contained in the top level.

There is only a few nodes in this directory. And of course, none of the ones I am interested in :)

I would like to understand why this happens and how can I influence the results reported in this directory.

Thank you in advance,

Michele

Parents
  • Andrew Beckett

    Hi Michele,

    The hbnoise_xf database gives the transfer function from each voltage or current source to the specified output - just as xf and pxf would do (for various peculiar reasons there is no separate hbxf analysis - mostly because the analyses are very similar). All "xf" analyses have the benefit of giving you the transfer function from any input to a single output in a single run - so if  you want to look at (say) supply rejection or image rejection they are really useful and much easier than having to keep moving around an "ac" source.

    You can also set the stimuli parameter to "nodes and terminals" in which case it gives you the transfer function from a voltage source in series with each device terminal or a current source onto each node. You have to save "currents" to get the voltage source transfer functions (because "currents" saves the terminal info). Then on the direct plot form you can click on the device terminals or nodes to get the appropriate transfer function (which will be one of voltage gain, current gain, transconductance or transimpedence) depending on whether the input was a voltage or current source and the output was a voltage different or a probed current.

    I just wanted to give the above info for completeness in case anyone else hit this issue.

    Regards,

    Andrew.

Reply
  • Andrew Beckett

    Hi Michele,

    The hbnoise_xf database gives the transfer function from each voltage or current source to the specified output - just as xf and pxf would do (for various peculiar reasons there is no separate hbxf analysis - mostly because the analyses are very similar). All "xf" analyses have the benefit of giving you the transfer function from any input to a single output in a single run - so if  you want to look at (say) supply rejection or image rejection they are really useful and much easier than having to keep moving around an "ac" source.

    You can also set the stimuli parameter to "nodes and terminals" in which case it gives you the transfer function from a voltage source in series with each device terminal or a current source onto each node. You have to save "currents" to get the voltage source transfer functions (because "currents" saves the terminal info). Then on the direct plot form you can click on the device terminals or nodes to get the appropriate transfer function (which will be one of voltage gain, current gain, transconductance or transimpedence) depending on whether the input was a voltage or current source and the output was a voltage different or a probed current.

    I just wanted to give the above info for completeness in case anyone else hit this issue.

    Regards,

    Andrew.

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