EP2S90F1020C5 Datasheet, PDF (739/768 Pages) Altera Corporation – Stratix II Device Handbook, Volume 1

Transmission
Line Layout
High-Speed Board Layout Guidelines
Table 11–1 shows the loss tangent value for FR-4 and GETEK materials.
Table 11–1. Loss Tangent Value of FR-4 & GETEK Materials
Manufacturer
GE Electromaterials
Isola Laminate Systems
Material
GETEK
FR-4
Loss Tangent Value
0.010 @ 1 MHz
0.019 @ 1 MHz
The transmission line is a trace and has a distributed mixture of
resistance (R), inductance (L), and capacitance (C). There are two types of
transmission line layouts, microstrip and stripline.
Figure 11–1 shows a microstrip transmission line layout, which refers to
a trace routed as the top or bottom layer of a PCB and has one
voltage-reference plane (power or ground). Figure 11–2 shows a stripline
transmission line layout, which uses a trace routed on the inside layer of
a PCB and has two voltage-reference planes (power and/or ground).
Figure 11–1. Microstrip Transmission Line Layout Note (1)
Trace
Dialectric Material
Power/GND
W
T
H
Note to Figure 11–1:
(1) W = width of trace, T = thickness of trace, and H = height between trace and
reference plane.
Figure 11–2. Stripline Transmission Line Layout Note (1)
W
Power/Ground
H
T
Trace
Dielectric Material
Power/Ground
Note to Figure 11–2:
(1) W = width of trace, T = thickness of trace, and H = height between trace and two
reference planes.
Altera Corporation
May 2007
11–3
Stratix II Device Handbook, Volume 2