PLL Macro Model Wizard

Hi Su Lim,

Please provide more information as to which IC version are you using and also exact Spectre version. Were you able to setup and run the VCO macro-model extraction testbench?  The reason I am asking so is because the Fig 16 you are refering is the top level pll bench which requires that both the macro model for VCO and PFD-CP has already been extracted and are now used for determine the PLL noise.

 Regards,

Ashish

 Hi Ashish,

   I am using IC6.1.4.9 with mmsim10.1

   My attempt to use the PLL Macrod Model Wizard was stopped dead on its track when I was trying to setup the testbench to run the macro model extraction of a VCO.

Regards,

Su Lim

Hi Su Lim,

For VCO macro model extraction you need to run the testbench as specified in Figure 4 (i.e.16-4 ) and not the one you are currently refering to as that is used for what I have mentioned previously. Please refer to PLL.pdf doc available in -

$MMSIMHOME/tools/spectre/examples/SpectreRF_workshop

directory. This is the Noise Aware PLL Flow Workshop document.

With Regards,

Ashish

 Hi Ashish,

   Thank you for pointing out the workshop document, my version of this document is dated January2010 and is apparently meant for MMSIM7.2.0.

  The FAQ section of the document mentioned that the problem "Unable to find VCO plugin in simulator library directory PLL Macro Model will be disable" can be resolved by adding this line

_pll_global_spectre_path = <spectre install dir>/tools/lnx86/spectre in the .cdsinit located within the working directory. I assumed that _pll_gloabl_spectre_path in the pdf-file is a typo and should be _pll_global_spectre_path

  Thanks!

Regards,

SU Lim

Hi SU lim,

Did you restarted your virtuoso session after making the changes in the .cdsinit?

I would suggest now to file a Service Request with Cadence so that this issue can be looked further.

Regarding the Helene's Paper, I think it was presented in CDN Live 2007 (as the dates in the paper suggests). Since then the way the sim is run from GUI has changed. There was no PLL Wizard in those days. Now those plugins get loaded from the PLL Wizard based on the settings you make there.

With Regards,

Ashish

Hi SU Lim,

One quick thing -

Can you set the suggested environment variable in your cshrc file as -

setenv _pll_global_spectre_path <spectre_install_dir>/tools/lnx86/spectre

and then source the cshrc and  restart the virtuoso session

Or

set the following command in .cdsinit file or in CIW,

setShellEnvVar(“_pll_global_spectre_path=<spectre_install_dir>/tools/lnx86/spectre”)

and restart the virtuoso session and see if this helps.

With Regards,

Ashish