More Details And Insight; Textbook Timing Equations - Intel VC820 - Desktop Board Motherboard Design Manual

3.4

More Details and Insight

3.4.1

Textbook Timing Equations

The "textbook" equations used to calculate the propagation rate of a PCB are the basis for
spreadsheet calculations for timing margin based on the component parameters. These equations
are:
Equation 3-6. Intrinsic Impedance
Equation 3-7. Stripline Intrinsic Propagation Speed
Equation 3-8. Microstrip Intrinsic Propagation Speed
Equation 3-9. Effective Propagation Speed
Equation 3-10. Effective Impedance
Equation 3-11. Distributed Trace Capacitance
Equation 3-12. Distributed Trace Inductance
®
Intel 820 Chipset Design Guide
=
Z
0
=
S
0 _ STRIPLINE
=
S 1017 .
0 _ MICROSTRIP
= ∗
S EFF S
0
=
Z
EFF
S
0
=
C
0
Z
= ∗
L 0 12 Z
Advanced System Bus Design
L
0
C
0
(Ω)
ε
1017 . *
r
(ns/ft)
ε
+
* 0 475 . * 0 67 .
r
(ns/ft)
C
D
+
1
C
0
(ns/ft)
Z
0
C
D
+
1
C
0
Ω
( )
0
(pF/ft)
∗
S
0 0
(nH/ft)
3-19