[SI-LIST] Re: uStrip question
- From: "joan vicent castell" <castell@xxxxxxxxxx>
- To: <bdempsey85@xxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Tue, 9 Mar 2004 09:27:53 +0100
Hi,
I suggest you to make two boarts. One about one inch long and the other
about five inches. Une the first one to calibrate as a thru and then measure
the long one. This will give you the S21 of a four inches trace.
Joan
UPC University
Catalonia
----- Original Message -----
From: "Bill Dempsey" <bdempsey85@xxxxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Tuesday, March 09, 2004 6:49 AM
Subject: [SI-LIST] Re: uStrip question
> Tom,
>
> We have a set of rt angle calibration connectors that we use to cal out
the
> coax + connector effect. These same "style" connectors (diff vendor) are
> used as the souce/load connection point to the PCB. They are of course
> soldered to the PCB -- that is to say they are not pressed or held in
place.
>
> Did I answer your question?
>
> One item of note -- the Smith chart is showing a mostly inductive tline.
>
> As part of this evaluation I built 3 tlines per board: one straight-thru,
> one with five 0402 custom sized packages with the terminals shorted, and
one
> with five 0603 packages...
>
> Interestingly the the tline with the 0603 pads (additional capacitance)
has
> much better performance (about 2.3dB loss vs. 6.5dB).
>
> Bill
>
>
> ----- Original Message -----
> From: "Tom Dagostino" <tom@xxxxxxxxxxxxx>
> To: <bdempsey85@xxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
> Sent: Monday, March 08, 2004 10:26 PM
> Subject: [SI-LIST] Re: uStrip question - repost
>
>
> > What you did not mention in your note may be the problem you are having.
> > How did you connect your VNA to the test articles? How clean was the
> > launch? It is easy to get large reflections from poorly designed
launches
> > that will affect S21
> >
> >
> > Tom Dagostino
> > Teraspeed Consulting Group LLC
> > Device Modeling Division
> > 13610 SW Harness Lane
> > Beaverton, OR 97008
> > 503-430-1065
> > tom@xxxxxxxxxxxxx <mailto:tom@xxxxxxxxxxxxx>
> >
> >
> > Teraspeed Consulting Group LLC
> > 2926 SE Yamhill St.
> > Portland, OR 97214
> > http://www.teraspeed.com
> >
> >
> >
> > -----Original Message-----
> > From: si-list-bounce@xxxxxxxxxxxxx
> > [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Bill Dempsey
> > Sent: Monday, March 08, 2004 7:57 PM
> > To: bdempsey85@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx
> > Subject: [SI-LIST] uStrip question - repost
> >
> >
> > --sorry for the repost but the server is adding junk to the message that
> > made it unclear to read --
> >
> > I recently built 3 different uStrip construction testboards and was
> > surprised by the results: it didn't work!
> >
> > I built two boards as trace over copper with soldermask and one board
> > as a co-planar waveguide. I constructed the geometries of the boards by
> > following the results of some "freebie" tools out there.
> >
> > After the boards were built I connected them to an HP network analyzer
> > (I calibrated out the cables/cons) to look at S21 response. What I
> > found was surprising. The S21 was extremely poor: approx 6.5dB loss
> > over 4". This just does not compare to the results of the tools I have
> > access to. I expected about 1.2 - 1.5 dB of loss at this frequency.
> >
> > Has anyone else out there had some bad experiences with uStrip @
> > 2.5GHz? What tools are you using? How are you correlating your
> > tool's results to real-world?
> >
> > The construction of the three boards was as follows:
> >
> > Board 1: 12 mil trace, 1/2 oz foil with 1 oz plating, 8 mil to gnd
(three
> > sheets of 1080 prepreg), 1oz copper gnd
> >
> > Board 2: (CPW): 8 mil trace, 8 mils to gnd (again, 3 sheets of 1080
> > prepreg), 6 mil to gnd return on signal layer, same plating/thicknesses
> >
> > Board 3: 4.75 mil trace, ~2.83 mils to gnd (one sheet of 1080 prepreg),
> > 1/2 oz foil, 1oz plating, 1oz copper gnd
> >
> > Regards,
> >
> > Bill
> >
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