Re: [SI-LIST] : Stub Capacitance calculation

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From: Scott McMorrow (scott@vasthorizons.com)
Date: Mon Jul 31 2000 - 01:32:41 PDT


Ron,

I agree. In fact, some packages contain stubs from pin to die which can be
1/4 wavelength.

scott

--
Scott McMorrow
Principal Engineer
SiQual, Signal Quality Engineering
18735 SW Boones Ferry Road
Tualatin, OR  97062-3090
(503) 885-1231
http://www.siqual.com

Ron Miller wrote:

> There is a problem with this simplistic approach, and that is that the quarter wave effect > becomes more important than the capacitance as frequencies get into the Gigahertz > range. If you must use SPICE then capacitance probably is the best you can do, but > regardless of the capacitance, as the stub approaches 1/4 wavelength, it approaches a > short in the frequency domain. This is real, not just theory. > > Ron Miller > > > -----Original Message----- > > From: Mendelsohn, Joseph P (Joseph) > > Sent: Tuesday, July 25, 2000 12:02 PM > > To: 'Prasanna S'; 'si-list@silab.eng.sun.com' > > Subject: RE: [SI-LIST] : Stub Capacitance calculation > > > > Check the url below for an Online calculator. It reports Co/unit length > > > > http://www.emclab.umr.edu/pcbtlc/microstrip.html > > > > > > -----Original Message----- > > From: Prasanna S [mailto:prasan@hclt.com] > > Sent: Tuesday, July 25, 2000 1:23 PM > > To: 'si-list@silab.eng.sun.com' > > Subject: [SI-LIST] : Stub Capacitance calculation > > Importance: High > > > > > > Hi All, > > How can I calculate the Capacitance of a Microstrip trace Stub > > with the trace routed in the component or top layer with a di-electric > > thickness of 3 mils under the trace.The di-electric constant is Er=4.0. > > and copper is 0.5 oz Can you give me the formula used for that? I am > > looking for the answer in pF/inch. > > > > Regards, > > Prasanna > > > > > > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to > > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP. > > si-list archives are accessible at http://www.qsl.net/wb6tpu > > **** > > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to > > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE > > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP. > > si-list archives are accessible at http://www.qsl.net/wb6tpu > > **** > > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP. > si-list archives are accessible at http://www.qsl.net/wb6tpu > ****

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