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 Need USEFUL, PRACTICAL, and FEASIBLE procedures to design, simulate, and layout "REAL RF Transformers" using Spectre RF 

Last post Sun, Feb 10 2013 5:32 AM by MicheleA. 5 replies.
Started by StillLearning 24 Jan 2013 09:03 AM. Topic has 5 replies and 1475 views
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  • Thu, Jan 24 2013 9:03 AM

    Need USEFUL, PRACTICAL, and FEASIBLE procedures to design, simulate, and layout "REAL RF Transformers" using Spectre RF Reply

    I am in need of "Useful," "Practical," and "Feasible" procedures on how to design, simulate, and layout RF Transformers using Spectre RF.

    I have not seen the real-world item in the "model library" of two of the major foundaries (I cannot name them due to the NDA I have signed). Therefore, I would like someone in this forum to provide me with the above information either himself/herself, or direct me to a resource that includes "ALL" of the above pieces of information.

    Unfortunately, I have not yet found a resource that meets the criteria mentioned in the Subject line above. They are mostly impractical and useless.

    I look forward to hearing from someone who could address my issue.  

    • Post Points: 20
  • Fri, Feb 8 2013 3:34 AM

    • MicheleA
    • Top 150 Contributor
    • Joined on Wed, Feb 1 2012
    • Den Bosch, Netherlands
    • Posts 60
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    Re: Need USEFUL, PRACTICAL, and FEASIBLE procedures to design, simulate, and layout "REAL RF Transformers" using Spectre RF Reply

    Maybe not the answer you were looking for, but I guess you can't work around an EM simulator for the task.

    In a Company I worked for, they could start a design from a Matlab script, where they implemented some basic equations. But of course that was only a first step. Then you have to sim your structure electromagnetically, and after that you can either work with [S] or - if you want to use SpectreRF - switch to a lumped element model.

    To get the full picture, you may consider reading this:

    http://www.nt.tuwien.ac.at/fileadmin/topics/RF_engineering/da/da/kehrer_da.pdf

    It is relatively old but the basics are all there nicely covered, IMO.

    Hope this helps, even a little bit.

    • Post Points: 20
  • Fri, Feb 8 2013 4:41 PM

    Re: Need USEFUL, PRACTICAL, and FEASIBLE procedures to design, simulate, and layout "REAL RF Transformers" using Spectre RF Reply
    Michele,

    Thank you for your attention and the link. I had a cursory review of this document (a thesis, it appears), and, unfortunately, it does not have the information I am looking for, as, like most other academic publications, it is useless at best. You know that most of the knowledge generated in academic world only suits the academic world, and never finds its way to the industry.

    I am looking for step-by-step, practical, and repeatable instructions from A to Z on how to design, layout, and simulate an integrated RF Transformer. Let me be clear: I need the procedure used in the “INDUSTRY.” I have read several academic publications and dissertations about this subject, and I can tell you that none of them was useful. I recently read a PhD dissertation on this subject from a reputable university in California, and it was waste of time.

    It is really frustrating that using an integrated RF transformer is not straight forward unlike other components such as inductors. I do not understand why the foundries do not have it in their libraries. Why do they make us jump through so many hoops?

     
    • Post Points: 20
  • Sat, Feb 9 2013 6:02 AM

    • MicheleA
    • Top 150 Contributor
    • Joined on Wed, Feb 1 2012
    • Den Bosch, Netherlands
    • Posts 60
    • Points 885
    Re: Need USEFUL, PRACTICAL, and FEASIBLE procedures to design, simulate, and layout "REAL RF Transformers" using Spectre RF Reply

    Hey there,

    a couple of comments :

    1 - I am not sure this topic fits well in this type of forum, being more design oriented and less tool oriented. Do you know www.edaboard.com? There's plenty of great design advice there, if you want to try it.

    2 - On a general note, being myself an industry designer, I know that there is a long path to go from a paper/thesis idea to a robust product for the market.

    3 - Nevertheless, the path to go is *after* you have a basic piece in place : this basic piece is usually the result of implementation of theory available from books/publications.

    4 - I have not clear what you mean with practical and repeatable instructions other than what I suggested. I am sure you can find more precise theoretical formulae for coupling and inductance with varying sizes/geometries, however I doubt you can find much more down-to-earth "recipes" than those. The rest of the path, as I said, is

    a) spot what defines your RF transfomer, in terms of specification. Chapter 1 of the linked material plus what suits your needs. 

    b) building a first order structure from book formulae. (you should be able to do it after reading the first 2 chapters of the thesis I linked, and having done some extra research as needed)

    c) simulating the structure with EM simulator (either 2.5 or 3D)

    d) extracting a model. Chapter 2 and 3 of the thesis I linked.

    e) using the model, gain understanding of which knobs act on your desired target performance. (RL,IL,BW,transform ratio,Lp,Ls)

    f) N iterations between c) and e)

    g) verify performance with interfacing blocks

    ...

    5 - Transformers are *not* standard devices (standard == digital in these days), plus they require a substantial amount of know-how to be designed properly. No surprise you don't find them in the PDKs. I would warn you that even inductors, but actually everything in RF, are *not* "straightforward". Their use needs careful consideration each step on the way, skills, reviews. That's what we get paid for, however, so I guess it's fair.

    I have worked only marginally with transfomers, basically building switching caps around a pre-defined and optimized inductive core, but I can maybe dig some extra info for you from my colleagues. You would then need to be specific however as far as which step of "the path" is posing you an issue.

    Again, I am not sure this is the right place for this kind of discussion. I would be glad to continue, should the need arise, but I would like to get a feedback from the moderators whether this is O.K. or not.

    Michele 

    • Post Points: 20
  • Sun, Feb 10 2013 4:40 AM

    Re: Need USEFUL, PRACTICAL, and FEASIBLE procedures to design, simulate, and layout "REAL RF Transformers" using Spectre RF Reply

    Michele,

    There is absolutely no problem with having this kind of discussion on these forums - design related topics are absolutely OK. Of course this will rely more on the community responding to such topics (rather than Cadence folks such as me). Whilst I have a design background, I've not been doing real design for a number of years now, so others will be much more current with design practices than I am - I only get it second hand from my experience as a designer in the past - and that's also likely to be true of some of the other Cadence AEs who respond here from time to time.

    Certainly there are other forums which are more design-centric - for example The Designer's Guide (I am much less active there than I used to be, due to lack of time, but it's a lively forum which covers design as well as tool topics).

    Regards,

    Andrew.

    • Post Points: 20
  • Sun, Feb 10 2013 5:32 AM

    • MicheleA
    • Top 150 Contributor
    • Joined on Wed, Feb 1 2012
    • Den Bosch, Netherlands
    • Posts 60
    • Points 885
    Re: Need USEFUL, PRACTICAL, and FEASIBLE procedures to design, simulate, and layout "REAL RF Transformers" using Spectre RF Reply

    Ok Andrew, thanks for your feedback. Let's see what comes from the OP now :)

    Michele 

    • Post Points: 5
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Started by StillLearning at 24 Jan 2013 09:03 AM. Topic has 5 replies.