I have been designing a PLL which gives an output frequency in the range (400-500)MHz to the reference input frequency of (20-25)MHz.So for doing the pnoise analysis I have added the PSS as well as Pnoise analysis
I have made the following as setup for the analysis for a frequency of 500MHz. I have chosen 1) shooting method instead of harmonic balance 2)beat frequency to be the output of the divider (divider ratio is 20) that is 25MHz and also output of the PLL is selected as divider out in Pnoise tab. But it seems that the PSS is not converging and thus pnoise is failing.
So please direct me with the procedure for PSS as well as Pnoise for a PLL not for VCO alone.
Cadence has a methodology for simulating the pnoise of a PLL in lieu
of a VCO. Have you examined either of these?
(Chapter 9 "Noise-Aware PLL Flow")
In reply to smlogan:
In reply to Jithin:
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.
Sr. Staff Support AE, Global Customer Support
Cadence Design Systems, Inc.
In reply to Tawna:
What is recommended PLL analysis flow in Cadence in IC6.16 with MMSIM13.1 at this moment in time?
Is it phase and voltage domain analysis as presented in "Virtuoso Spectre Circuit Simulator RF Analysis Library Reference" (Version 13.1)?
Could you explain why the noise-aware PLL flow has been discontinued?
In reply to benlau:
The PLL Noise Aware flow was discontinued for a number of reasons. I won't go into all of them here. One being the database associated contained proprietary data/IP from the Cadence RF Methodology Kit. As such, certain legal documents (SPLA+ SPLA Kit exhibit) to be signed before the database could be released. It was not available to University students as well. There were limitations with some of the models in the PLL Noise Aware flow database.
In addition to the reasons Tawna gave, it proved difficult to support the many different architectures of subblocks used in PLLs, and we found that there wasn't significant adoption of the technology to warrant greater investment in improving the technology, especially as in many cases people could either use behavioural simulation of the entire PLL or use of phase-domain modelling approaches.
In fact we have some upcoming events in Europe which cover PLL verification (as well as ADC verification) and which will talk about using a phase-domain modelling approach (follow the link to see the details)
I suggest that you take a look at the PLL Verification Workshop, which is available for download at http://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:DocumentViewer;src=wp;q=ProductInformation/Custom_IC_Design/ApplicationPackages/CIC_RAK_Home.htm (an ADC Verification Workshop can also be downloaded there).
In reply to Frank Wiedmann:
Thanks Frank- I meant to mention those. These are aligned with the presentation material that we're using in the upcoming Technology on Tour events in Europe, and earlier similar seminars in North America.
In reply to Andrew Beckett:
Thank you Frank, Andrew. I received a response from Cadence support with exact proposal and already looking at the materials.