Contact an Expert

Thread: SOLT cal short or open fringe parameters


Permlink Replies: 73 - Pages: 5 [ Previous | 1 2 3 4 5 ] - Last Post: Apr 24, 2012 12:43 PM Last Post By: Lucux
Lucux

Posts: 54
Registered: 08/21/09
Re: SOLT cal short or open fringe parameters
Posted: Jul 18, 2011 12:44 AM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
Attachment fw.JPG (94.0 KB)
Attachment of.JPG (73.7 KB)
thanks Dr. Joel

I upgraded the FW to A.09.42.01, and recalled it again. the problem still exists. see the attached please.

can you help review this and see if there is any other possible issues which caused this weird looking plot?

PS. i did not open the file so there is no extra space or something unnecessary added.
Lucux

Posts: 54
Registered: 08/21/09
Re: SOLT cal short or open fringe parameters
Posted: Jul 27, 2011 9:20 PM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
Dr. Joel

any comment?
Dr_joel


Posts: 2,688
Registered: 12/01/05
Re: SOLT cal short or open fringe parameters
Posted: Jul 27, 2011 9:53 PM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
I thought I did respond, sorry. I just loaded it in A.09.33.12 and I don't see any problem at all.
I also tried it on A.09.42.01. No problem at all. Maybe you could try downloading the file from this forum website and try opening it again, instead of using your local file.
Lucux

Posts: 54
Registered: 08/21/09
Re: SOLT cal short or open fringe parameters
Posted: Jul 28, 2011 1:08 AM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
thanks Dr. Joel

this sounds weird to me. i did download it from the forum.

besides the frimware, is there any other factor that might affect PNA's recall function?
Dr_joel


Posts: 2,688
Registered: 12/01/05
Re: SOLT cal short or open fringe parameters
Posted: Jul 28, 2011 1:32 AM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
sometimes the language setting can cause trouble, if the radix is set to , instead of .
Dr_joel


Posts: 2,688
Registered: 12/01/05
Re: SOLT cal short or open fringe parameters
Posted: Jul 28, 2011 1:36 AM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
Attachment Mod_OF.s1p (80.2 KB)
Try this one. I added a ".0" after the 6. It works in mine, but so did the other one!
Lucux

Posts: 54
Registered: 08/21/09
Re: SOLT cal short or open fringe parameters
Posted: Jul 28, 2011 7:30 PM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
Attachment untitled00.JPG (83.3 KB)
Attachment 1.png (11.9 KB)
thanks Dr. Joel

i'm afraid this really confused me. i noticed you have added ".0" in the file. i recalled your Mod_OF.s1p, the problem is still there. see the attached plot.

what is your PNA model number? does it affect?
Dr_joel


Posts: 2,688
Registered: 12/01/05
Re: SOLT cal short or open fringe parameters
Posted: Aug 2, 2011 8:01 AM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
I've got no good answer for you. I am using an N5242A, but I doubt that is the problem.
I have seen some problems in the past with languange settings affecting the way files are read. I can only say that I read the file in just fine when I tried it last time. Curiously, I think I did see a problem the first time I read it, but I cannot repeat that issue.

Other ideas are: maybe it is something with the size of the file and all the comment lines in the file, which is unusual for an S2P file (comments are typically not inserted in the body of the S2P file, but at the beginning).

It cleaarly appears related to the end of the file, as though the last line is being read in and a new line is created with a frequency matching the last imaginary number. Leads me to believe something is reading in the numbers incorrectly in your case, but as I say, I can't reproduce it. maybe someone else can chime in.
daras


Posts: 884
Registered: 12/01/05
Re: SOLT cal short or open fringe parameters
Posted: Aug 2, 2011 9:55 AM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
Attachment s1p.png (124.6 KB)
Works fine on my PNA too.

Image
Lucux

Posts: 54
Registered: 08/21/09
Re: SOLT cal short or open fringe parameters
Posted: Aug 2, 2011 9:51 PM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
Attachment gamma data.JPG (136.7 KB)
Thanks a lot Joel, and thanks daras for the trial.

I did a trial where I did not select "Include Gamma and Impedance Comments” when doing data export from Ansoft HFSS. Everything works well now.

I have been reading the Touchstone file format reference material. Here is what I found from the web.

http://vhdl.org/ibis/connector/touchstone_spec11.pdf

But I cannot find description on what gamma data are used for. Do you have any idea on what gamma data is used for? Or what are they?

In other words, if there is no gamma data in the s1p file, is there any impact on its recalled result?
Dr_joel


Posts: 2,688
Registered: 12/01/05
Re: SOLT cal short or open fringe parameters
Posted: Aug 2, 2011 10:39 PM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
No, I suspect that the gamma values are an attempt to deal with the fact that the S2P file does not allow input and output impedances to be different (a defect that is corrected in the proposed version 2, which no one uses yet). Those gamma values were really just comment lines, and are not used by any S2P file reader that I know.
Lucux

Posts: 54
Registered: 08/21/09
Re: SOLT cal short or open fringe parameters
Posted: Aug 3, 2011 12:02 AM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
thanks Dr. Joel

I assume you are saying it dosn't affect the recalled result.

I used the method to generate all fringe parameters and generated the ckt file. I then tried with a pair of adaptor to verify if the kit I have worked on works ok or not.

I have got the weird looking S21 or S12 plot. there are many ripples in the plot. some peaks even go above zero.

do you know why this happens? what can i do to improve this?
Dr_joel


Posts: 2,688
Registered: 12/01/05
Re: SOLT cal short or open fringe parameters
Posted: Aug 3, 2011 8:28 AM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
From your display you have two issues: a short cycle ripple with a frequency pattern of about 125 MHz, and a long cycle ripple of a few GHz. The short cycle ripple is almost undoubtably due to cable length.

It could be a loose or unstable cable during the calibration. The other cause is poor residual source match and load response in the cal kit.

THe ripple pattern has a p-p of about 0.2 dB, indicating a combination of residual source match and raw load match of about -40 dB. If the raw load match is on the order of -15 dB, that means your residual source match plus load match together is on the order of -25 dB, not too spectactular.

You can look at the raw source and load match directly using the calset viewer.
Lucux

Posts: 54
Registered: 08/21/09
Re: SOLT cal short or open fringe parameters
Posted: Aug 3, 2011 11:44 PM   in response to: Lucux in response to: Lucux
Click to report abuse...   Click to reply to this thread Reply
thanks Dr. Jeol

I understand you said there are two patterns of ripple, and long and a short cyble ripple.

I have done this test a few times, every time I have the same reult. so a loose or unstable system cable during calibration can be excluded.

when you say residual source match and load response, do you mean the load is not ideal and have some return loss?

how can i improve this?

thanks again.

Point your RSS reader here for a feed of the latest messages in all forums