Abhijit Wander

The PCIe standard has successfully doubled its per-lane bandwidth across seven generations while maintaining full backward compatibility. PCIe Gen8 continues this legacy, targeting 256 GT/s per lane using PAM4 signaling. However, with each new generation, achieving backward compatibility within the same mechanical envelope becomes increasingly complex. Follow along as Abhijit Wander explores how sustaining bandwidth scalability beyond Gen7 may ultimately require both electrical and mechanical innovation rather than purely material or footprint optimization.

In the second part of this article series on navigating signal integrity challenges, Abhijit Wander showcases a marked improvement in signal integrity performance, specifically in connector-only scenarios, by transitioning from a microstrip to a stripline footprint design.

With PCIe Gen7 on the horizon, expected to debut around 2025 at a staggering 128 GT/s data rate and a pad-to-pad channel loss budget shift from -32 dB at 16GHz to -36 dB at 32 GHz, this article delves into the evolving performance requirements for Gen7 connectors and details the pivotal design changes needed to meet these demands. The study delves into meticulous design refinements in both the add-in card and baseboard components, addressing challenges such as signal integrity concerns, ground-mode resonances, and the delicate balance between signal performance and mechanical reliability.