[SI-LIST] Re: Question Concerning End Launch SMA connector.
- From: "Swanson, Dan" <Dan_Swanson@xxxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Wed, 9 Apr 2003 08:00:09 -0400
Dear Gustavo,
It is possible to design an end launch out to 15GHz.
One responder mentioned poor results with thin microstrip
layers. For that case you need to relieve the ground
plane under the center pin. Placement of ground vias relative
to the connector "legs" and the microstrip ground will
also impact your results. The center pin should be small
diameter and short (50 mils long max). Johnson components makes
a connector with small, rectangular tab. They also have one
that drops into a slot on the edge of the board, have not
tried that one myself.
For your second question. You can get to the stripline
layer accurately by building a set of calibration
standards that include the connector and the
via transition to stripline. For a TRL cal these
would just be several different lengths of stripline.
You still want to design the end launch and via
transition to have good match, otherwise you are just
adding more "noise" to the calibration process.
You need to search the microwave literature for
TRL cal, LRL cal and de-embedding. Probably some
Agilent App notes on the subject.
Details on connector transitions and via transition design
can be found in my new book, due out in June from Artech House.
Full color illustrations all the way through.
http://www.artechhouse.com/default.asp?Frame=Book.asp&Book=1-58053-308-6&Cou
ntry=US&Continent=NO&State=MA
Dan
Dan Swanson EMAIL: d.swanson@xxxxxxxx
Forem USA PHONE: 978-834-4085
37 South Hunt Road FAX: 978-388-7077
Amesbury, MA 01913
> -----Original Message-----
> From: Gustavo Blando [mailto:gblando@xxxxxxxxxxxx]
> Sent: Tuesday, April 08, 2003 3:41 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Question Concerning End Launch SMA connector.
>
>
>
>
> Hello Si people.
> I need to better understand the proper way to interface to a test
> board with "maybe" end launch SMA connector in order to maintain
> a constant impedance over a very wide frequency rage > 15GHz or so.
> This is for a 2.5GB/s - 3.125GB/s application and I have a lot of
> flexibility
> of how to design the test board.
>
> Here are the questions:
>
> 1. In your experience which is the best connector, (or way of connect)
> for the interface between board and connector.
> I am going to be injecting TDR/VNA signals.
>
> 2. The papers I've seen deals with this transition to a
> micro-strip structure (top layer routing).
> What about If I want to test a Strip line??
>
> 2.a. Have any of you been able to put one/two vias to
> transition to
> an stripline, and then successfully extract
> one/two vias from
> the measurement ??. (For Example)
> [CONN] -> Connector
> [VIA] -> Via
> [uST] -> u-strip line
> [SST] -> StripLine
> [SST(Real)] -> Stripline that I want to measure.
> [S] --> S Parameters
> [T] --> T Parameters
>
> Setup on the test board, only used to extract
> the connection
> setting
>
> ====================================================================
> [CONN]--[uST]--[VIA]--[SST]--[VIA]--[uST]--[CONN] (Test
> Setup)
> Extract Sparameters from here ---> [S]
> [S] -> Convert to ---> [T] => [T] = [T(1/2)] *
> [T(1/2)] =
> [T(1/2)]^2
>
> => [T(1/2)] = sqrt([T])
> (This part I am not sure, since sqrt([T]) will
> give me two
> results,
> and I won't know which one to pick????)
>
>
> Setup that Includes above structure + the
> "real" structure
> to measure.
>
> ===============================================================
>
> [CONN]--[uST]--[VIA]--[SST/2][SST(Real)][SST/2]--[VIA]--[uST]-
> -[CONN] (Test
> Setup)
> Extract Sparameters from there --->[Stotal]
> [Stotal] -> Convert to [Ttotal].
> [T(I want)] = [T(1/2)]^-1 * [Ttotal] * [T(1/2)]^-1
> [T (I want)] --> Convert to [S (I want)]
>
> Is this doable????, Have you done it???.
> Is there a better way to do this?.
>
> Any information, papers, will be greatly appreciated.
> Thanks.
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