Question on test scheme design for 4-port microstrip circuit - RF Cafe Forums

 Post subject: Question on test scheme design for 4-port microstrip circuit

Posted: Thu Sep 24, 2009 2:39 pm 

Dear all,

I designed a small four-port microstrip circuit (device under test), and obtained the simulation results. Since this 4-port microstrip circuit is very small, it does not have enough space for SMA connector mounting. Now I want (but I have no idea) to design a proper test scheme for purpose of the SMA-connector measurement of S parameters of this tiny four-port DUT by using four-port vector network analyzer. I really appreciate whatever help you could offer me on the test scheme design.

Thanks a lot.

Sincerely yours,
Kevin

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Pursuing perfectness pushes us to progress

 Post subject: Re: Question on test scheme design for 4-port microstrip circuit

Posted: Thu Sep 24, 2009 3:46 pm 

Hi Sageme,

If you only have a couple DUTs to measure, then you can probably solder a short section of small semi-rigid coax to the board that has an SMA on the other end. I've had great success with that up into the 6 GHz region (could probably go higher, butI've never needed to).

For measuring a large number of DUTs, a fixture will be necessary. I've never used one myself, but I see that a company called Gigalane has a productio quality fixture for measuring your type of PCB.



http://www.gigalane.com/index.html?mode=02_01_01_01&pduid=93

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Thanks,
Jess

 Post subject: Re: Question on test scheme design for 4-port microstrip circuit

Posted: Mon Sep 28, 2009 12:13 pm 

Dear Jessica,

Thanks a lot for the information your provided.

Actually, I only have a couple of DUTs to measure. I think it may be very difficult to solder a short section of small semi-rigid coax to the board for measurement, since our DUTs are so miniature that it may not have enough space for soldering. The distance between two adjacent ports is about 36mil=0.9mm on the same side (as indicated in the picture above), and the distance between adjacent port is about 164mil=4.2mm on two adjacent sides, which is the same as the DUT's length.

For the test fixture in your reply, it might be not proper for our measurement for the same reason that our DUT is too miniature. I checked the specifications of this test fixture. It requires that minimum length of DUT is 9mm and minimum width of DUT is 2.5mm.

What do you think of this? Or could you please offer some suggestions? Thank you so much!

Sincerely,
Kevin

_________________
Pursuing perfectness pushes us to progress