[SI-LIST] Re: de-embedding of mems
- From: Kaustubh Bhate <kbhate@xxxxxxxxxxx>
- To: Dan.Swanson@xxxxxxxxxx
- Date: Tue, 23 Sep 2003 16:43:30 +0100 (IST)
Hi Dan,
Thanks for your reply.
But I was under the impression (I may be mistaken)that the values quoted for
mems devices like switches,for eg, were in reference to a identical thru-line.
In case of active devices like transistors they are completely isolated from
all
other parasitics and the calculated de-embedded data is isolated.
While, in case of a mems device, for eg, the insertion loss of a mems switch
with interconnects is calculated by comparing to the insertion loss of a
identical thruline in the absence of the switch.
Would that be correct, if yes, what would be the method to de-embed the mems
device from the interconnects and pads.
Thanks.
Regards,
Kaustubh.
>From: "Swanson, Dan" <Dan.Swanson@xxxxxxxxxx>
>To: "'kbhate@xxxxxxxxxxx'" <kbhate@xxxxxxxxxxx>, si-list@xxxxxxxxxxxxx
>Subject: RE: [SI-LIST] de-embedding of mems
>Date: Tue, 23 Sep 2003 08:57:37 -0400
>MIME-Version: 1.0
>
>Kaustubh,
>
>True de-embedding is more complicated than what
>you are describing. To accurately de-embed a
>DUT from its fixture you compute the S-paramters
>of each half of the fixture from the connector
>to the plane of the DUT.
>
>To get the S-parameters of the fixture, you basically
>have to do a second set of "calibration" measurements
>on each half of the fixture. The math and the techniques
>are exactly the same as those used to calibrate your
>vector network analyzer. So you might use several known
>loads (short, open, load) or you might use several
>known lengths of transmission line (TRL).
>
>Once you get the parameters of the fixture, you can
>mathematically remove the fixture from the global
>measurement of the fixture plus DUT.
>
>An alternative would be to calibrate the ANA and fixture
>all in one go. All your cal standards are at the DUT plane.
>Have to know how to modify the standard cal procedure or
>cal coefficients.
>
>>
>> De-embedding for mems passive componenst would be different
>> than for the active
>> devices like transistors where the de-embedded parameters are
>> not referenced to,
>> any "entity".
>>
>I don't understand this statement. True de-embedding described
>above is the same for active and passive devices.
>
>Agilent used to have some App notes on the math of ANA calibration.
>What they call an "error model" can be interpreted as the parameters
>of your fixture. There is also a lot in the RF/microwave literature
>on various schemes for de-embedding.
>
>Dan
>
>
>> -----Original Message-----
>> From: Kaustubh Bhate [mailto:kbhate@xxxxxxxxxxx]
>> Sent: Tuesday, September 23, 2003 7:57 AM
>> To: si-list@xxxxxxxxxxxxx
>> Subject: [SI-LIST] de-embedding of mems
>>
>>
>> Hi,
>> Can somebody point me to a standard/known procedure for doing
>> de-embedding of
>> mems measurements?
>>
>> I have seen a paper that subtracts the insertion loss (in
>> dB)of an identical
>> thru-line from "a mems-switch-interconnect" assembly
>> measurement(in dB).Is that
>> a correct/reasonable approach of eliminating the loss from
>> the pad parasitics
>> and the interconnects?
>> If the the raw s-parameters are subtracted for the same, as
>> above,(instead of at
>> the dB level) the results are totally different.
>>
>> Also what about de-embedding for return loss? Using the same
>> approach as above
>> (working in the dB domain), the results do not make sense.
>>
>> De-embedding for mems passive componenst would be different
>> than for the active
>> devices like transistors where the de-embedded parameters are
>> not referenced to,
>> any "entity".
>>
>> Thanks in advance.
>>
>>
>> Regards,
>>
>>
>> Kaustubh Bhate
>> Transducers Group
>> NMRC
>> LEE Maltings
>> Prospect Row
>> Cork.
>> Ph:353 21 4904401
>>
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>>
>
>
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Kaustubh Bhate
Transducers Group
NMRC
LEE Maltings
Prospect Row
Cork.
Ph:353 21 4904401
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