[SI-LIST] Re: uStrip - now it works!
- From: "Scott McMorrow" <scott@xxxxxxxxxxxxx>
- To: bdempsey85@xxxxxxxxxxx
- Date: Thu, 11 Mar 2004 07:24:49 -0800
Those pesky SMA launches strike again!
bdempsey85 wrote:
>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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>
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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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