
4–72
Altera Corporation
Stratix GX Device Handbook, Volume 3
February 2005
Transmission Lines
Figure 4–71. Impedance Profiles of SMA Connectors, Measured by TDR
Crosstalk
If two traces are close to each other, the signal switching on one trace can
excite a voltage on the other, resulting in crosstalk. Crosstalk control must
be a key objective of any board design. With high-speed designs it is
especially important because of the reduced noise margins.
The following crosstalk case studies are simulations that vary the spacing
between the aggressor net and the victim net. Both simulations used
differential traces.
Crosstalk Case Study 1 – Loosely Coupled Microstrip Traces
This case study used two pairs of 1-inch long microstrip differential
traces. The width (W) of all the traces is 5 mils. The spacing between the
positive and negative loosely coupled traces is 15 mils. The aggressor
trace had the same configuration, but was placed at varying distances to