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  1. #1
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    How to choose optimal wire width of spiral coil to attain high q factor?

    How to choose optimal wire width of spiral coil to attain high q factor? There are formula to calculate optimal turns n pitch. Is it by trail n error to choose wire width?

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    Re: How to choose optimal wire width of spiral coil to attain high q factor?

    Hi,

    High Q means low loss.

    What are the losses in a coil?
    * core loss --> choose a core that is suitable for frequency and flux
    * ohmic winding loss --> choose wires with high (overall) wire cross section, and short length if possible
    * loss due to proximity effects --> chose useful layer stacking
    * loss due to skin effect --> choose HF litz instead of one solid wire
    * others?

    For each of these effects there are numerous documents, tutorials, application notes, calculations ... in the internet.

    Thus: No, it's no "trial and error".

    But as with every development: it starts with your requirements.
    Frequency, waveform, currents, size, cost, Q factor.....

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



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    Re: How to choose optimal wire width of spiral coil to attain high q factor?

    Quote Originally Posted by KlausST View Post
    Hi,

    High Q means low loss.

    What are the losses in a coil?
    * core loss --> choose a core that is suitable for frequency and flux
    * ohmic winding loss --> choose wires with high (overall) wire cross section, and short length if possible
    * loss due to proximity effects --> chose useful layer stacking
    * loss due to skin effect --> choose HF litz instead of one solid wire
    * others?

    For each of these effects there are numerous documents, tutorials, application notes, calculations ... in the internet.

    Thus: No, it's no "trial and error".

    But as with every development: it starts with your requirements.
    Frequency, waveform, currents, size, cost, Q factor.....

    Klaus
    Thanks for your valuable suggestion. Nice n informative.



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    Re: How to choose optimal wire width of spiral coil to attain high q factor?

    A problem with spiral inductors is that when you increase
    W, looking for Q, you also force the L to grow somewhat
    for the same core area. So you won't get the W2/W1
    improvement in series R, that you might imagine. You
    also increase the stray C (coil bottom area) and self-C
    (coil length), bringing down your SRF and your Q.

    Some foundries have "inductor tool kits" for specific
    processes. Absent this, cut and try and keep track.


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    Re: How to choose optimal wire width of spiral coil to attain high q factor?

    All major vendors of EM analysis tools - Integrand (EMX), Helic (VeloceRF), Lorentz (PeakView) - provide tools to synthesize an inductor layout to desired characteristics (L, Q, ...).


    1 members found this post helpful.

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    Re: How to choose optimal wire width of spiral coil to attain high q factor?

    For various values of wire radius, pitch and internal radius (given that fixed outer diameter) have been simulated using HFSS. It shows that least value of Q is 8 n maximum is 467267. Is this maximum value permissible?

    - - - Updated - - -

    For maximum Q, series resistance should be minimum. For the purpose of minimizing R, i have chosen mimimal wire radius of 0.12mm. But when i increased wire radius to 0.3mm(but decreased turns) i found increased value of Q.



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    Re: How to choose optimal wire width of spiral coil to attain high q factor?

    This shows that your evaluation of Q is not what others discuss.



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