[SI-LIST] Re: TDR measure / Simulation

But I have the dielectric constant,distance etc of pcb. Is 
impossible to have it exactly.

The patterns material is metal and It has a typical 
propagation,no?



Missatge original de "Peterson, James F (EHCOE)" 
<james.f.peterson@xxxxxxxxxxxxx>:




Calibration is the key, and it isn't easy unless you have 
a long trace =
test run of which you know the exact length.=20

I've found TDR's do certain things really well, they 
measure =
reflections, impedance, and time very accurately.=20

But there are things they do that need calibration : 
distance and the =
dielectric constant. If you have a length that is really 
accurate then =
you can derive the Er and thus prop delay of your other 
traces. But on a =
regular board I could get no closer than 10-20% because of 
the =
parasitics that lengthened the edges (vias, stubs, 
probe/launch =
attachments).

If you don't have an accurate Er then prop times won't 
agree in your =
sims and measurements.

Jim Peterson
Honeywell

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-
bounce@xxxxxxxxxxxxx] =
On Behalf Of si09604@xxxxxxxxxxxx
Sent: Tuesday, November 27, 2007 10:23 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] TDR measure / Simulation

Hello,
I try to understand the TDR (Time domain reflection) in=20
the measure and in the simulation, to identify the=20
elements.=20
I have seen that The TDR measure is more long in time 
that=20
the simulation.=20

Do you know what happens?

Thank you.

B.R

N=FAria
-----------------------------------------------------------
-------
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 technical documents are available at:
                http://www.si-list.net

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

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
  



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

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: