Tawna Wilsey Blog

Re: APS license usage

Tawna — Mon, 01 Apr 2013 19:51:29 GMT

Note: COS solution 1154566 has been replaced with COS Article 20044367.

Re: An error with Momentum S parameter blocks in Spectre

Tawna — Thu, 07 Mar 2013 17:43:30 GMT

I can help with Spectre debugging...but not Momentum (I've not used Momentum). Sorry! However, note that the error message you reported is a Spectre error message.

For Momentum issues, you may want to contact the Momentum support folks. (This is a Cadence Community forum.)

best regards,

Tawna

Re: An error with Momentum S parameter blocks in Spectre

Tawna — Thu, 07 Mar 2013 17:13:38 GMT

You didn’t mention your nport settings nor the version of spectre that you are using.

Please provide that. I suspect your nport settings are the issue.

Also, I am assuming that your s-parameter files are in touchstone, CITI, or spectre format.

Best regards,
Tawna

Re: Pnoise analysis

Tawna — Tue, 05 Mar 2013 17:38:30 GMT

Hi Shawn, Jithin,

The PLL Noise Aware flow is no longer recommended. It is being (or has been) removed from the documentation in MMSIM12.1.

You may also want to look at transient/transient noise analysis.

Best regards,

Tawna

RE: adding white and flicker noise sources in cadence virtuoso

Tawna — Fri, 15 Feb 2013 00:29:05 GMT

Hi OneNewBoy,

Quick answer…

Use transient analysis. (transient noise)

Use the latest versions of MMSIM. (Note that there were some issues with the psp103 trannoise model which are being fixed in MMSIM11.1 ISR23.)

If you are using IC615…

You may want to check out the Spectrum Assistant Appnote at:

http://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:DocumentViewer;src=wp;q=ApplicationNotes/Custom_IC_Design/SpectrumAppNoteV1.0.pdf

If using IC614, use the spectrumMeas function in ADE-L/XL

You can also look at the OCEAN reference manual (information on spectrum function):

http://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:DocumentViewer;src=pubs;q=/oceanref/oceanref6.1.5/chap10.html

And also the spectrumMeas function, see Appendix D of the ViVA tool user guide:

http://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:DocumentViewer;src=pubs;q=/wavescanug/wavescanug6.1.5/appD.html

Best regards,

Tawna

RE: Information on dc_pivot_check option

Tawna — Thu, 31 Jan 2013 16:25:47 GMT

Hi Dmitry,

RE:

I'm simulating a circuit and get the following notice from Spectre:

To improve dc performance, the options "dc_pivot_check=yes"

and "pivotdc=yes" were added in MMSIM 11.1 isr11.

If you see this warning in your log file, the DC analysis may be having difficulty converging.

Setting dc_pivot_check = yes may help.

This message doesn't affect anything - it just gives you a hint on how to improve the

performance if dc analysis is slow.

The difference between these two options: pivotdc and dc_pivot_check:

With pivotdc=yes, it will perform pivoting on every iteration of DC analysis,

trying to overcome convergence difficulty without overhead consideration.

With dc_pivot_check=yes, it will perform pivoting only when the pivot is worse

than certain threshold. This way it may help improve the DC convergence or even

performance without introducing much overhead.

We will be enhancing spectre –h to include a more descriptive explanation.

Best regards,

Tawna

RE: Data update issue using SpectreRF MATLAB toolbox

Tawna — Wed, 30 Jan 2013 20:38:46 GMT

Hi Nikhil,

Whenever asking a question to the Forum, it is important to put in the subversion of all the tools you are using.

(virtuoso, matlab, spectreRF). Also, there needs to be exact error or warning messages.

Often times, questions are so vague that people don’t bother answering them.

Please look at the Guidelines for the RF Forum .

Best regards,

Tawna

RE: Phase noise simulation in ring oscillator

Tawna — Wed, 16 Jan 2013 17:20:13 GMT

Hi Ayrin,

You still haven’t provided the section of your netlist containing options and analysis statements.

I’m sure it’s a setup issue.

Also, you are using an extremely old version of spectre that is no longer supported.

Please upgrade to MMSIM12.1.

Best regards,

Tawna

RE: Phase noise simulation in ring oscillator

Tawna — Tue, 15 Jan 2013 21:25:00 GMT

Hi Ayrin,

There’s not much to go on here… It would be helpful to have more information.

For starters,

The subversion of MMSIM you are using
Your analyses and options statements from the netlist.
I assume you are using the shooting engine.
Is this an injection locked ring oscillator?
Have you looked at solution 11784002 on Cadence Online support and followed the suggestions there?

Best regards,
Tawna

RE: No Insufficient Memory Promble in PSS/Pnoise simulation

Tawna — Thu, 27 Dec 2012 21:11:30 GMT

Hi Charley,

If this is a VCO like a ring oscillator (strongly nonlinear, sharp waveforms), use shooting engine with full spectrum pnoise.

If a crystal oscillator or LC oscillator, use the harmonic balance engine.

To speed things up, use APS. You can also set parasitic reduction (see spectre -h for more information). For example:
spectre +aps +parasitics=rf input.scs

best regards,
Tawna