Chapter 3. Channel Modeling and Design Methodology

Chuck Yuan, Ravi Kollipara, Dan Oh, and Hao Shi

The passive interconnect (or channel), along with the transmitter (Tx) and receiver (Rx), is one of the three primary components of an I/O system. The channel connects the Tx with an Rx. The signal from the Tx may be distorted by the passive channel due to channel loss, dispersion, reflection, and crosstalk. When the data rate is sufficiently low, we can ignore the impact of the passive channel. At multi-gigabit data rates, the channel becomes the limiting factor in achieving a target data rate. Furthermore, the impact of the channel is strongly dependent on the signaling method used. Specifically, for a given data rate, the channel has a greater impact on single-ended signaling than on differential signaling due to single-ended signaling’s higher crosstalk and simultaneous switching noise. In modern designs, the impact of the passive channel cannot be neglected and must be evaluated.