[SI-LIST] Re: Ansoft Q2D and Swept Impedance Parameters
- From: "Bill Beale" <beale@xxxxxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Thu, 11 Dec 2003 10:59:50 -0800
Hi Doug,
It sounds like your doing the fast sweep. If so, use a discrete sweep =
instead. I have not seen that behavior with the discrete sweep.
Of course, the discrete sweep take a lot longer to run, so I usually run =
them over night.
Thanx,
Bill
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Bill Beale Phone: 503-439-3462
Sr. App. Engineer Fax: 503-466-9472
Accelerant Networks e-mail: bill_beale@xxxxxxxxxxxxxx
On the world wide web @ http://www.accelerant.net
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> All,
> I have been using Ansoft Q2D to generate tabular w-element=20
> models for
> lossy striplines. The geometries are fairly typical of what=20
> you might
> see on a high-speed differential pair for a serial link on a=20
> backplane.
> I'm doing an impedance-sweep up to 20GHz. For certain geometries, the
> frequency-dependent resistance is incorrect. What I'm seeing when I
> plot R(f) is that above some frequency, say
> 1GHz, the impedance curve begins to "flatten out", and no=20
> longer follows
> the sqrt(f) relationship. The flattening is quite significant. Now,
> for a subset of these problematic geometries, increasing the=20
> # of iterations in the sweep mitigates the problem. For the=20
> others, it
> appears that nothing can be done in the solution setup. =20
> Ansoft is aware
> of the problem (they say that it is a numerical one), but have
> not prioritized its resolution. There are some non-ideal workarounds
> such as cutting the data off below some frequency and=20
> extrapolating from
> there...but I was wondering if any of you have seen this problem
> and if so, have you determined an effective solution?
> =20
> Thanks,
> =20
> Doug White
> Cisco Systems=20
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