[SI-LIST] Re: Need some Info on Inductance..
- From: "Rich Peyton" <p2rich@xxxxxxxxxxxxx>
- To: <amahajan@xxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Mon, 31 Mar 2003 08:21:16 -0500
Very good questions - Connector pin companies all have there own way of
characterizing their pins, weather it is by internal source, or external
independent testing company characterizing their pins.
We use a "Gnd-Signal-Return-Gnd" 3 x 4 row, Gnd pins surrounding Signal =
&
Return pin type of configuration installed into a test block because =
this
would be the configuration you would use operating at very high =
frequencies.
The Sig & Return are tested at a certain pitch, say 1mm which gives your
ideal impedance of 50 Ohms, it is tested and modeled at this =
configuration.
It is a good idea to state the data regarding the test block material, =
also
(Er, dimensions, freq range used, test equipment,etc..) In this set-up =
when
you have an advertised inductance it is "Loop Inductance" advertised.
"Partial Inductance" is calculated using rule of thumbs, or where the =
return
line is unknown etc...=20
I've posted a question before regarding the usefulness of this data. In
regards to a customer who uses connector pins, what data is most =
important
since they will be changing configuration of pins, material & set-up? I =
may
have posted it a couple times, but received no replies. I always say =
that
data supplied gives you loop inductance values under ideal matched =
impedance
conditions, but if the customer is changing those conditions, they need =
to
expect those values to change. They need to apply there own testing =
process
once they configure the pins towards there own application (Real
World)--Connector pin companies cannot possibly characterize every type =
of
configuration there could be in regards of their pin (Testing of pins =
can be
quite expensive). I'd love to hear from anyone on this list regarding =
how
useful the data supplied (Data & models) from connector pin companies is
towards them, what data is of use when you are in the decision stage? =20
As stated by someone else who replied to your question, GigaTest has a =
lot
of interesting Articles by Eric Bogatin, they also characterize pins for =
a
lot of companies.
Regards,
Rich=20
=20
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On
Behalf Of Abhijit Mahajan
Sent: Friday, March 28, 2003 2:04 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Need some Info on Inductance..
Dear All,
I want to find out more information on via inductance and inductance of=20
connector pins. Specifically, I am confused as to how the inductance of =
such structures is specified/determined.
As an example, when someone says the via/pin inductance is *nH what is=20
their assumption about the current loop? Am I right in thinking that=20
when people talk of via inductance, they actually mean the inductance of =
a closed loop formed by a pair of vias divided by two? How is L=20
typically determined?
Also could someone explain the term partial inductance?
If these questions have been answered earlier, I will be grateful if=20
someone can send me the link.
Thank you experts.
Abhijit.
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