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Any tool to automatically curve fit for pre-defined model (Read 14802 times)
aaron_do
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Any tool to automatically curve fit for pre-defined model
Dec 14th, 2011, 12:37am
 
Hi all,


just wondering, if I have an inductor's S-parameters for example, is there any software tool which will allow me to input my own RLC model, and then give me a best fit?


thanks,
Aaron
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ywguo
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Re: Any tool to automatically curve fit for pre-defined model
Reply #1 - Dec 27th, 2011, 4:23am
 
Origin is good.
http://en.wikipedia.org/wiki/Origin_(software)
There are several open-source clones according to Wikipedia.  :)

Yawei
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Re: Any tool to automatically curve fit for pre-defined model
Reply #2 - Jan 2nd, 2012, 1:34am
 
Hi,

another good software doing this (and much more) is Aplac  :)!! It is a good analog circuit simulator which contains also good optimizers.

Bye Stephan
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RFICDUDE
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Re: Any tool to automatically curve fit for pre-defined model
Reply #3 - Jan 2nd, 2012, 2:15pm
 
I have used the optimization tools in ADS to fit inductor models, but over the past few years I have some success using the nport model for Spectre when working with S-parameter data from EM simulators or measurements.

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aaron_do
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Re: Any tool to automatically curve fit for pre-defined model
Reply #4 - Jan 2nd, 2012, 5:50pm
 
Hi all,


I've had a look at the responses, but I'm not sure if they do what I was asking.

1. Origin. I've used this before and as I remember its a bit like microsoft excel. Am I looking at the wrong software? How would you use it to create an RLC model? thanks!

2. Aplac. Actually I haven't been able to get much information on this tool. Do you have any link which shows how it can accomplish what I need?

3. ADS. As I understand it, the only ways to do it in ADS are by manually curve fitting using the tuner, or using their own pre-defined networks. Am I missing something?

Manual curve fitting can be very tedious especially when the model becomes complicated. Also, the predefined models from ADS (ladder, pi, T...) sometimes result in models which lose their physical meaning or are overly complicated. This makes it difficult to find problem areas in the circuit and modify as necessary.

I figured that since all PDK inductors, capacitors and resistors (components really) need some RLC model, there would be some software which would automatically generate the parameters for a user-defined model based on S-parameters.


thanks,
Aaron
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Frank Wiedmann
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Re: Any tool to automatically curve fit for pre-defined model
Reply #5 - Jan 3rd, 2012, 2:30am
 
There is an article at http://www.sonnetsoftware.com/support/downloads/publications/TransDec07CompactSy... that describes an approach where the topology is also selected automatically. This is currently available in Sonnet as an unsupported hidden feature. If you have a Sonnet license and would like to try it, you should contact Sonnet support and ask them for details.

Sonnet had originally planned to introduce fitting to a pre-defined model in the current release 13 (see section III of http://www.sonnetsoftware.com/support/downloads/publications/PID1626063.pdf). However, there have apparently been unexpected problems with the implementation of this feature, so it has been postponed until release 14.

Another company that offers tools for fitting passive structures is http://www.idemworks.com/ (see also http://www.emc.polito.it/software/IdEM/idem_home.asp and http://www.emc.polito.it/publications/pub_type.asp?autore=Grivet-Talocia).
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« Last Edit: Jan 3rd, 2012, 4:33am by Frank Wiedmann »  
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Frank Wiedmann
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Re: Any tool to automatically curve fit for pre-defined model
Reply #6 - Jan 4th, 2012, 4:54am
 
In the meantime, I downloaded the trial version of IdEM from http://www.emc.polito.it/software/IdEM/idem_home.asp and played around with it a bit. It does not allow you to fit to a pre-defined model, but it can generate a netlist model suitable for transient simulation from S-parameter data (similar to Sonnet's Broadband Spice Extraction, see http://www.sonnetsoftware.com/products/sonnet-suites/bb_spice.html).

The trial version of IdEM is limited to 2 ports and order 20, which should be perfectly adequate for a normal inductor. For building the model, I selected the FDVF-AS algorithm with minimum order 2 and maximum order 20. After that, I used the Hamiltonian passivity check and compensated the model if necessary. Finally, I checked the accuracy of the model and generated the Spice model.
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aaron_do
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Re: Any tool to automatically curve fit for pre-defined model
Reply #7 - Jan 4th, 2012, 5:07pm
 
Hi Frank,


thanks for the reply. So I suppose the full version allows multiple ports? It sounds like ADS's Spice Model Generator does the same thing though (I'm not familiar with this area).


thanks,
Aaron
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Frank Wiedmann
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Re: Any tool to automatically curve fit for pre-defined model
Reply #8 - Jan 5th, 2012, 4:40am
 
I would expect that the full version of IdEM has no arbitrary limits. I have no experience with the Spice Model Generator from ADS.
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aaron_do
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Re: Any tool to automatically curve fit for pre-defined model
Reply #9 - Jan 6th, 2012, 10:33pm
 
A guy from Integrand (they make EMX) came over to my company to give a talk and answer our questions. EMX also has a model generator program, but like the others, it can only use pre-defined models. I asked him about whether or not user-defined models would be possible, and he said many customers have asked about that, but at the moment, the software just isn't at that level yet.

What I understood from him about IDEM's software is that it generates a netlist using voltage-controlled sources (something along those lines anyway) etc, not user-defined models. So they are very accurate, but are really only useful for running transient analysis - not for design iteration.


regards,
Aaron
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Frank Wiedmann
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Re: Any tool to automatically curve fit for pre-defined model
Reply #10 - Jan 7th, 2012, 9:49am
 
aaron_do wrote on Jan 6th, 2012, 10:33pm:
What I understood from him about IDEM's software is that it generates a netlist using voltage-controlled sources (something along those lines anyway) etc, not user-defined models. So they are very accurate, but are really only useful for running transient analysis - not for design iteration.

That's absolutely correct. If you want go get direct insight into your design from the parameter values of the fitted model, then IdEM is not the right tool for you.
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Frank Wiedmann
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Re: Any tool to automatically curve fit for pre-defined model
Reply #11 - Mar 21st, 2012, 8:08am
 
Frank Wiedmann wrote on Jan 3rd, 2012, 2:30am:
Sonnet had originally planned to introduce fitting to a pre-defined model in the current release 13 (see section III of http://www.sonnetsoftware.com/support/downloads/publications/PID1626063.pdf). However, there have apparently been unexpected problems with the implementation of this feature, so it has been postponed until release 14.

This feature is now available in beta test, see http://www.sonnetsoftware.com/support/files/beta/inductor_model_extractor_beta.p....
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