[SI-LIST] Re: Hanging Stub or via

Qazi,
   It is my experience that you should keep the stubs to a minimum.  At 
test are you looking to test the device or the test fixture.  If it is the 
former then run the controlled impedance trace to the relay via and then 
off to the test head.  I do not recommend you split the trace, since you 
will have a voltage divider and get half the amplitude as well as a bunch 
of reflections.   The small stub of the relay is about as good as you will 
get, and should not terribly effect the results for which you are testing.
   If you would like to prove it out, get some coax and hand wire the 
device with a big stub and with a just the relay stub.  You will see the 
difference right away.

Good luck
-Ed





At 03:10 PM 4/27/2005 -0700, Qazi Arif Iqbal wrote:
>Hi Gurus,
>
>I need your opinion regarding which of the following would be better.
>
>1. From the DUT pin a 50 ohm Trace going to a pin of a relay from which it
>brances out to two different places. One is the high speed trace that goes
>straight to the tester pin and other going through the same relay (speed not
>a factor) when the relay is switched on. So if I keep the relay off, my high
>speed line would see a DUT pin to a relay pin (via) and then the tester pin.
>2. On the other possible option is to branch out the whole thing at the DUT
>pin. From DUT one branch would (my high speed line) go to the tester and the
>other branch would go to the relay ( a considerable trace length)through
>which it would go to the Tester. So if I keep the relay off, my high speed
>line would see a hanging stub of trace for the other branch.
>
>I was wondering which option would be better.
>
>Thanks in advance,
>Qazi
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx
>[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of
>Christopher.Jakubiec@xxxxxxxxxxxx
>Sent: Wednesday, April 27, 2005 8:17 AM
>To: CurtM@xxxxxxxxxxx; roymesi@xxxxxxxxx; si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: diode connected between source & drain - why?
>
>
>Vertical Power MOSFETs are designed specifically to handle a certain
>amount of energy through this diode per the data sheet.  Logic MOSFETs
>most likely do not care about this parameter.
>
>Chris
>
>-----Original Message-----
>From: Curt McNamara [mailto:CurtM@xxxxxxxxxxx]=20
>Sent: Wednesday, April 27, 2005 10:19 AM
>To: Jakubiec Christopher (IFNA AI QM CM); roymesi@xxxxxxxxx;
>si-list@xxxxxxxxxxxxx
>Subject: RE: [SI-LIST] Re: diode connected between source & drain - why?
>
>
>My experience with the body diode (as I understand it, a by-product of
>device construction) is that you *should not* depend on it to clamp an
>inductive kick-back. There is simply too much energy for it to=20
>dissipate, and you will destroy the FET. Use an external diode clamp
>which is rated for the energy -- these should only cost a few=20
>cents.
>
>                                       Curt
>
>Curt McNamara. P.E.=20
>Senior Electrical Engineer=20
>Logic Product Development=20
>411 Washington Ave. N Suite 101=20
>Minneapolis, MN 55401=20
>Tel 612-436-5178=20
>Fax 612-672-0443=20
>curtm@xxxxxxxxxxx=20
>www.logicpd.com=20
>This message (including any attachments) contains confidential
>information intended for a specific individual and purpose, and is
>protected by law. If you are not the intended recipient, you should
>delete this message and are hereby notified that any disclosure,
>copying, or distribution of this message, or the taking of any action
>based on it, is strictly prohibited.
>
>
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
>On Behalf Of Christopher.Jakubiec@xxxxxxxxxxxx
>Sent: Wednesday, April 27, 2005 7:44 AM
>To: roymesi@xxxxxxxxx; si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: diode connected between source & drain - why?
>
>
>Hi Roy,
>
>When current is switching through an inductive load, a reverse EMF is
>generated when the current is turned off.  This diode allows a path for
>this current in this situation.  This body diode comes built into the
>MOSFET for free, and is not an extra device.
>
>A diode connected MOSFET behaves like a diode, while a standard
>connected MOSFET behaves like a switch with a diode in the body.
>
>-Chris
>
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
>On Behalf Of Roy M.
>Sent: Wednesday, April 27, 2005 9:21 AM
>To: si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] diode connected between source & drain - why?
>
>
>Hi,
>Can someone explain to me why are they Transistors (mosfets), that has a
>diode connected between the source and the drain? I tried to find
>something on the internet, but nothing... i don't understand what's the
>difference between a regular mosfet and a
>diode-connected-source-drain-mosfet.
>Thanks!
>Roy
>------------------------------------------------------------------
>To unsubscribe from si-list:
>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
>or to administer your membership from a web page, go to:
>http://www.freelists.org/webpage/si-list
>
>For help:
>si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>List FAQ wiki page is located at:
>                 http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
>List technical documents are available at:
>                 http://www.si-list.org
>
>List archives are viewable at:    =3D20
>                 http://www.freelists.org/archives/si-list
>or at our remote archives:
>                 http://groups.yahoo.com/group/si-list/messages
>Old (prior to June 6, 2001) list archives are viewable at:
>                 http://www.qsl.net/wb6tpu
>  =3D20
>------------------------------------------------------------------
>To unsubscribe from si-list:
>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
>or to administer your membership from a web page, go to:
>http://www.freelists.org/webpage/si-list
>
>For help:
>si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>List FAQ wiki page is located at:
>                 http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
>List technical documents are available at:
>                 http://www.si-list.org
>
>List archives are viewable at:    =20
>                 http://www.freelists.org/archives/si-list
>or at our remote archives:
>                 http://groups.yahoo.com/group/si-list/messages
>Old (prior to June 6, 2001) list archives are viewable at:
>                 http://www.qsl.net/wb6tpu
>  =20
>------------------------------------------------------------------
>To unsubscribe from si-list:
>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
>or to administer your membership from a web page, go to:
>http://www.freelists.org/webpage/si-list
>
>For help:
>si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>List FAQ wiki page is located at:
>                 http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
>List technical documents are available at:
>                 http://www.si-list.org
>
>List archives are viewable at:
>                 http://www.freelists.org/archives/si-list
>or at our remote archives:
>                 http://groups.yahoo.com/group/si-list/messages
>Old (prior to June 6, 2001) list archives are viewable at:
>                 http://www.qsl.net/wb6tpu
>
>
>
>
>--
>  PRIVACY WARNING: For auditing purposes, a copy of this message has been
>  saved in a permanent database.
>
>
>
>--
>  PRIVACY WARNING: For auditing purposes, a copy of this message has been
>  saved in a permanent database.
>------------------------------------------------------------------
>To unsubscribe from si-list:
>si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
>or to administer your membership from a web page, go to:
>http://www.freelists.org/webpage/si-list
>
>For help:
>si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>List FAQ wiki page is located at:
>                 http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
>List technical documents are available at:
>                 http://www.si-list.org
>
>List archives are viewable at:
>                 http://www.freelists.org/archives/si-list
>or at our remote archives:
>                 http://groups.yahoo.com/group/si-list/messages
>Old (prior to June 6, 2001) list archives are viewable at:
>                 http://www.qsl.net/wb6tpu
>
>
>
>!DSPAM:42701218203211317119348!

------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl?Si-List_FAQ

List technical documents are available at:
                http://www.si-list.org

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu

Other related posts: