Hi Kaustubh,

In general, de-embedding is an art, not a science. It should be avoided
whenever possible.
The best technique strongly depends on the exact device (including all pads
and interconnects) you are measuring since you are de-embedding to remove
the effects of specific portions of your overall structure. Also, it is all
too easy to remove effects that are actually aspects of a design or process
that cannot removed, thus providing an overly optimistic assessment of
device performance.

Cho and Burk is aimed at transistor modeling. If your layout and substrate
parasitics are similar to the bipolar transistors they were modeling, taking
this whole is a reasonable approach. If not, then you need to have the right
"calibration" structures to derive the de-embedding elements. Note that the
actual device they were modeling was much smaller than the gap between
tranmission lines so that they removed a substantial shunt inductance by
putting the stub in all of their calibration structures. Typically, a MEMS
switch should only be deembedded between uniform transmission line planes
since that is the way it would usually be used in an RF system. If you
de-embed all the way down to just the basic bridge or cantilever, the
results are only narrowly useful.

Best of luck!

Art

Arthur S. Morris III, Ph.D.              art.morris@wispry.com
CTO, VP Eng.                             v: 1-919-657-8101
wiSpry, Inc.                             f: 1-919-854-7501
4001 Weston Parkway, Suite 200           http://www.wispry.com/
Cary, NC 27513


> -----Original Message-----
> From: mems-talk-bounces+art_morris=ieee.org@memsnet.org
> [mailto:mems-talk-bounces+art_morris=ieee.org@memsnet.org]On Behalf Of
> mems-talk-request@memsnet.org
> Sent: Wednesday, September 03, 2003 12:02 PM
> To: mems-talk@memsnet.org
> Subject: MEMS-talk Digest, Vol 11, Issue 2
>

> ------------------------------
>
> Message: 6
> Date: Wed, 3 Sep 2003 06:22:38 -0700 (PDT)
> From: kaustubh bhate 
> Subject: [mems-talk] de-embedding mems switch measurements
> To: mems-talk@memsnet.org
> Message-ID: <20030903132238.40892.qmail@web41106.mail.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> Hi,
> Can someone recommend me a reliable method to do the
> de-embedding of rf-mems switch measurements?
> I have tried to follow the paper :"A three-step method
> for the de-embedding of high frequency s-parameter
> measurements", by Cho and Burk, but wonder if that is
> valid for mems devices.
> I have series and shunt capacitive mems-switches on a
> lossy substrate.
>
> Thanks in advance.
>
> Regards,
> Kaustubh.
>
>
> ****************************************