[SI-LIST] Re: Spiral Inductor

Hi Daniel,
I am designing these inductors for WLAN applications
(5GHz - 6GHz). My problem is that, the Q falls to zero
before 5GHz and starts rising again. Forms something
like a wave. If we observe the smith chart, the
s-paramters follow the same pattern, forming circles.
I need the Q to fall to zero after 6 GHz i.e inc the
SRF. I have tried the following ways
1. hole in  the gound plane... right below and above
the spiral 
2. via holes in the spiral...reduce capacitance to
gound..
I will also be trying some stacked spiral combinations
and helical inductors..
but neither the option 1,2 showed any change in the
srf. So am in a kinda fix. Any suggestions?
thank you.
-VJ

PS: am using hfss...
--- D G <dgun@xxxxxxxxxx> wrote:
> 
> From: Vijay Varadarajan <varvij@xxxxxxxxx>
> > 
> > Hi,
> > I am working on an embedded inductor in LTCC for
> > 5-6GHz operations. Does anyone have ideas on
> > increasing the self - resonant frequency? Thank
> you.
> > -VJ
> > PS: Am using copper conductors with top and ground
> planes.
> 
> This is probably obvious, but use less capacitance
> and try parallel resistance.  That means keeping
> ground planes away and possibly using embedded
> parallel resistors to damp any resonance (if the
> process allows it).  There's not much you can do
> about capacitance between windings.
> 
> Is this a narrowband or broadband problem?
> 
> --
> Daniel
> 
> 
> -- 
>
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