Performance analysis of multi-gigahertz parallel bus with transmit pre-emphasis equalization

The performance of multi-gigahertz interconnect systems is adversely impacted by non-ideal physical effects such as attenuation, crosstalk, impedance mismatches, intersymbol interference, and by parameter variations due to process and environmental changes. Many of these non-ideal physical effects can be mitigated by selecting proper signaling topologies and techniques, by using judicious design rules, and by applying advanced circuitry and signal processing techniques. However, the parameter variations due to process and environmental conditions are more difficult to overcome, and their impact on a system needs to be quantified in order to ensure robust system operation under the worst-case operating conditions. This paper describes the design and characterization methodology used to develop robust multi-gigahertz systems using conventional interconnect and packaging technologies. It focuses on studying the sensitivity of the performance of the system to parameter variations due to process and environmental changes. The simulation and measurement results of high-speed equalized channels are presented. The performance of the equalized channels is also verified by comparing the measured and simulated eye diagrams for various values of equalization coefficients for data rates above 6.4 GHz. Finally, the sensitivity of equalization taps to parameter variations is also studied.