[SI-LIST] Re: In EBD model?
- From: "Beal, Weston" <weston_beal@xxxxxxxxxxx>
- To: "'si-list@xxxxxxxxxxxxx'" <si-list@xxxxxxxxxxxxx>
- Date: Mon, 16 Jul 2001 13:51:10 -0700
Inmyung,
The "Len" parameter specifies the length of a trace segment. Each trace
segment could have different electrical properties so the trace is divided into
many "Len" statements in the path description.
In this case the "Len = 0" represents a via, but in general it simply means
that the L, C, and R are considered lumped instead of distributed. It is legal
to write "Len = 0 R = 50 /" to represent a 50 ohm series resistor.
The units on the parameters are Henries for inductance, Farads for Capacitance,
and Ohms for resistance. The length unit is arbitrary as long it is the same
for all the parameters. I could make up a new length unit called a stel (it
means nothing) and use that unit because it gets cancelled out in the math.
Len = 2 stel L = 5nH/stel C = 2pF/stel R = 2 Ohm/stel
The impedance of the transmission line segment is:
Z = sqrt(L/C) = sqrt( (5nH/stel)/ (2pF/stel) ) = sqrt( 5nH/2pF )
The length unit went away. Now the delay of the transmission line is
Td = sqrt(LC)*Len = sqrt( (5nH/stel) * (2pF/stel) ) * 2 stel
= sqrt( 5nH * 2pF )/stel * 2 stel = sqrt(5nH*2pF)*2
and again the length unit went away since it was the same unit for all the
parameters. And that is why I love math.
Regards,
Weston
-----Original Message-----
From: Inmyung Song [mailto:imsong@xxxxxxxxxxxxxx]
Sent: Sunday, July 15, 2001 10:37 PM
To: Signal Integrity Mail Group
Subject: [SI-LIST] In EBD model?
Good morning everyone.
In EBD model, the keyword Len is the length of pattern, right?
This IBIS is generated.
[Path Description] /XUPCBD(0)
Pin A6
Len = 0.0414555 L = 2.47486e-007 C = 2.11203e-010 R = 2.56347 /
Len = 0.011303 L = 2.37766e-007 C = 2.5134e-010 R = 2.56347 /
Len = 0.000898026 L = 2.47486e-007 C = 2.11203e-010 R = 2.56347 /
Len = 0.0035921 L = 2.41418e-007 C = 2.57775e-010 R = 2.56347 /
Len = 0.0237123 L = 2.47486e-007 C = 2.11203e-010 R = 2.56347 /
Len = 0 L = 6.03614e-010 C = 2.08724e-013 /
Len = 0 L = 6.03614e-010 C = 2.08724e-013 /
Len = 0.00450031 L = 3.07164e-007 C = 1.22917e-010 R = 5.12693 /
Node U2.54
1. The pattern connected with A6 is routed only Comp and Sold, why the Len is
multiple?
What does it mean?
2. Len = 0, is Via here, right?(The pattern connected with A6 has no discrete
component)
3. L, C, R's dimension is what? nH/inch, pF/inch, ohms/inch? or nH/mm, pF/mm,
ohms/mm?
Any comment is helpful to me.
Thank you for your reading.
Inmyung.
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