Transmission Line Primer
Jetson AGX Xavier Series Product
DG-09840-001_v2.5 | 134
21.5
Transmission Lines and Reference
Planes
Defining an appropriate reference plane is vital to transmission line performance due to
crosstalk and EMI issues. The following points explore appropriate reference plane
identification and characteristics for optimal signal integrity:
Transmission line return current (Figure 21-4)
•
High-speed return current follows the path of least inductance.
•
The lowest inductance path for a transmission line is right underneath the
transmission line; i(D) is proportional to:
Figure 21-4. Transmission Line Height
Transmission line return current:
•
High-speed return current follows the path of least inductance.
•
The lowest inductance path for a transmission line is the portion of the line closest to
the dielectric surface; i(D) is proportional to
1
(
1 + D
H
2
)
Crosstalk on solid reference plane (Figure 21-5):
•
Crosstalk is caused by the mutual inductance of two parallel traces.
•
Crosstalk at the second trace is proportional to
1
(
1 + D
H
2
)
•
The signals need to be properly spaced to minimize crosstalk
