Chapter 9. Lossy Lines, Rise-Time Degradation, and Material Properties

A signal with a very fast edge going into a long transmission line will come out with a longer rise time. As an example, the measured response of a 50-psec signal transported through a 36-inch-long, 50-Ohm backplane line in FR4 is shown in Figure 9-1. The rise-time has been increased to almost 1 nsec. This rise-time degradation is due to the losses in the transmission line and gives rise to intersymbol interference (ISI) and the collapse of the eye diagram.

Measured input and output signals through a 50-Ohm line, 36 inches long. A 50-psec rise-time signal goes in, while a 1-nsec rise-time signal comes out.

Figure 9-1. Measured input and output signals through a 50-Ohm line, 36 inches long. A 50-psec rise-time signal goes in, ...

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