[SI-LIST] Re: About agilent PLTS-AFR
- From: Hassan O. Ali <hassan@xxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Mon, 1 Jul 2013 10:52:12 -0400
Any new fixture removal techniques should be welcome since I think
Automatic Fixture Removal in PLTS is a work in progress - at best. It
has some practical limitations that we were surprised to see for our
fixtures of interest.
We have a 3-port application - 1 port at the input and 2 ports at
the output. The 1-port is a coaxial connector connected to a
microstrip line. The 2 ports at the output are tightly-coupled, GSSG,
grounded coplanar waveguides that transition to two single-ended
grounded coplanar waveguides and ultimately connected to end-launch
coax connectors.
We have two back-to-back fixtures as per PLTS guidelines, one for
the input and the other for the output. The magnitude results are
quite off (~2dB off) even in simulation where the back-to-back
fixtures are made exactly identical to the fixtures connected to the
DUT. The PLTS also misses the location of the resonances by more than
1GHz! The results are worse on the actual boards where it's impossible
to have back-to-back fixtures identical to those connected to the DUT.
The phase matches very well.
We were surprised to see that the PLTS tool doesn't come with any
tuning knobs. You get what you get! I'd expect, say an option for
tying weights to what matters e.g. insertion loss higher weight than
return loss, a frequency band that tighter match is needed than the
rest, etc.
Does anyone have an experience with PLTS with assymmetric fixture
like the one described above? I'd appreciate any useful tips.
Best regards,
Hassan.
On Mon 07/01/13 3:24 AM , steve weir weirsi@xxxxxxxxxx sent:
Begin by reading every paper that you can about handling issues with
measured S parameter data, in particular papers that deal with the
issues that arise from finite frequency steps in the data sets. Then
devise a validation plan for your conversions and data
manipulations.
Then compose or collect representative data sets with known
features.
Then start designing and testing your algorithms. When you have
something that looks stable then start feeding it S parameter data
with
known features that is less than perfect. Adjust and iterate as
needed.
Steve.
On 7/1/2013 12:52 AM, ye tao wrote:
> Because I did not buy PLTS, and I want to try it use matlab or
ads.
> If it is a very complicated job, maybe I will give up.
> How to split a s-param to half, it is a funny thing.I am
interested in it.
> beginning, I thought it was just a simple matrix operations. But
> later,I found this approach is not feasible.Now,I have no idea,I
hope
> you give me some advice.
>
> 2013/7/1 steve weir
>
> It's possible. To do it well is a major effort. It would make
a good
> senior project in quantitative electromagnetics. Why do you
want to
> reinvent this wheel?
>
> Steve.
>
> On 6/30/2013 11:59 PM, ye tao wrote:
> > Hello Experts:
> > I know in the PLTS2013��have AFR(Automatic Fixture
Removal) ��it is
> > better than TRL.
> > But, I want to do it in ADS or Matlab environment, is it
impossible?
> >
> > I read some paper, but I can��t find the theory of AFR.
The most
> important
> > thing is split the S-parament to half.
> >
> > I think it need to covert freq domin to time domin,and cut
off ,
> then
> > covert time domin to freq domin. This way can split the
> S-parament to half?
> > Is it right?
> >
> > Who can help me? Thanks
> >
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