[SI-LIST] Re: 4-Port VNA calibration question
- From: steve weir <weirsi@xxxxxxxxxx>
- To: Virendra <adsurevv@xxxxxxxxx>,si-list@xxxxxxxxxxxxx
- Date: Mon, 17 Apr 2006 10:38:28 -0700
Virenda, the problem with Pico-Probes is that the
50 ohm performance makes assumptions about the
air and metal around the probe ends. If you try
to combine asymmetric probes in close proximity,
my intuition tells me you may find it very hard
to get repeatable results unless you always have
the two sets at exactly the same spacing and
angle to each other etc. If both probe sets are
identical, then you should see less
variation. You can always take this up with your
probe vendor and see if they think I am all wet.
Steve.
At 10:31 AM 4/17/2006, Virendra wrote:
>Steve,
>I don't think i understood you correctly about
>getting a new pair. Maybe i should state my
>problem more numerically. With the setup i have
>one pair of probes (port 1 and 2) which are less
>than 200um in pitch and other pair of probes
>(port 3 and 4) which are more than 800um in
>pitch. As for why the change, it is a new structure.
>
>thanks again,
>Virendra
>
>steve weir <weirsi@xxxxxxxxxx> wrote:
>Virenda, that sounds like a recipe for trouble to me. I would go out
>and buy a match to the new pair or exchange the new pair for a match
>with the old pair. Why did you change geometry?
>
>Steve.
>At 10:01 AM 4/17/2006, Virendra wrote:
> >Hi All,
> >I have a question about calibrating a VNA for 4-port
> >measurements. We are using standard pico probes and Agilent 87xxX
> >VNA. The problems we are having is that one pair of probes now have
> >different pitch than the other pair and it is not possible to use
> >the same calibration substrate for both the pairs. Does anyone know
> >a way to calibrate this kind of setup with two different calibration
> >substrates?
> >thanks in advance,
> >Virendra
> >
> >
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