[SI-LIST] uStrip - now it works!
- From: "bdempsey85" <bdempsey85@xxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Wed, 10 Mar 2004 12:27:05 -0600
All,
I thought I would post my results from today's experiment. Yesterday
the traffic coming back from the server and privately was to examine the
launch -- i.e. the connectors.
I cut off the edges of the PCB and mounted and end-launch SMAs to the
board. Even as poor as my connection is I have max loss of 1dB on S21!
So this tells me (and any listeners) that the connector can (and did)
kill!
Thanks to all who responded to my first post.
Regards,
Bill
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of bdempsey85
> Sent: Tuesday, March 09, 2004 10:06 AM
> To: 'Scott McMorrow'; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: uStrip question
>
> I'm off to do that in just a few minutes. Some quick lab work last
> night was showing that our end-launched designs are working..
>
>
> The TDR analysis will hopefully show that the design-to-impedance
> numbers are right on.
>
>
>
>
>
> Bill
>
> -----Original Message-----
> From: Scott McMorrow [mailto:scott@xxxxxxxxxxxxx]
> Sent: Tuesday, March 09, 2004 8:22 AM
> To: bdempsey85@xxxxxxxxxxx
> Subject: Re: [SI-LIST] Re: uStrip question
>
>
>
> Bill
>
> Have you done a TDR of the traces to see what your impedance is, and
if
> there are any launch anomolies off the SMA's/
>
> scott
>
>
> Bill Dempsey wrote:
>
>
>
> 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" <mailto:tom@xxxxxxxxxxxxx> <tom@xxxxxxxxxxxxx>
> To: <mailto:bdempsey85@xxxxxxxxxxx> <bdempsey85@xxxxxxxxxxx>;
> <mailto:si-list@xxxxxxxxxxxxx> <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>
<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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> --
> Scott McMorrow
> Teraspeed Consulting Group LLC
> 2926 SE Yamhill St.
> Portland, OR 97214
> (503) 239-5536
> http://www.teraspeed.com
>
>
>
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