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spiral inductor design

OK so I want to make a spiral (actually rectangular) RF Inductor on the surface of the PCB.  Multisim has single RF Inductor component which as far as I can tell is pretty much a virtual component.

 

I cannot seem to find any thing in either Multisim or Ultiboard that will address this problem - say I want a 220nH inductor - how do I get it.  I'm prepared to specify the track width and spacing (let's say 5/5), and as far as I can tell, if there isn't a ground plane this will be about 7 turns with an exernal dimension of about 200 mils and room for a via in the middle.  This is based on a *lot* of web trawling this afternoon.

 

However I would dearly love to be able to tell MS/UB that I want one of these please and the value should be 220nH, and that there is (or is not) a ground plane and how far away it is if present.

 

Is there in fact such a capability in MS/UB?  Or do I have to use (e.g.) http://smirc.stanford.edu/spiralCalc.html and allow for the fact that it will only give me a ball park figure, and than laboriously draw the component by hand?

 

Thanks

Dave

Message Edited by david_c_partridge on 12-19-2008 12:16 PM
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Hi Dave,

 

I hope you are well.  Your application sounds very interesting.  One suggestion would be that you can place line (trace) on the copper layers but you have to know the dimension for the inductor.  If the inductor is circular you will have to create a dxf file and import it into Ultiboard.

 

I hope this information helps.

 

Wishing you a Merry Christmas and a Happy New Year!!

 

Kind regards,

Prashant M
Applications Engineer
NI UK & Ireland

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Not at all the answer I was looking for I fear.  Oh well ...

 

D.

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I couldn't find the functionality that you're looking for in Ultiboard. But even without a tool to create inductor geometries, it seems like it would be nice to have at least an example. Obviously the stack up of the board changes things, but just having a sample would get you in the ballpark. Has anyone from the other forums that you've been browsing posted a gerber/dxf/protel/ultiboard of a spiral inductor?

 

Perhaps you could pirate their design and adjust your number of turns and the trace width/spacing etc. for the properties of your stack up. 

 

1) Would that even be helpful?

2) Can you find any example layouts? (I couldn't)

 

As to the tool, I would suggest making a product suggestion. The group that drives development for Ultiboard/Multisim would love to get your feedback as they consider what to work on next. http://digital.ni.com/applications/psc.nsf/default?OpenForm

 

I saw that there is a user group on Yahoo that has some layout utilities for making spiral inductors, but it looks like they are specific to Protel. Even so, getting a look at those scripts might be beneficial if you're going to be doing this a lot.

 

 

Daniel

Conditioned Measurements Hardware 

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