Investigation of Package Crosstalk and Impact to 28-32Gbps Transceiver Jitter Margin

Jitter margin loss as result of crosstalk impairment emerges as increasing challenge at 28Gbps and beyond. As silicon compensation is known ineffective to crosstalk, package becomes critical path of system jitter margin. At this speed, signal coupling needs to be kept at well below -50dB in order to ensure adequate insertion-loss-to-coupling ratio (ICR) for protocol jitter compliance. In this paper, we studied coupling mechanism and design options to achieve -50dB to -70dB coupling for devices used in 28G long reach, mixed long reach, short reach environments. Furthermore, we solved the myth of power-ground co-referencing for high speed transceivers. The investigation is carried out by theoretical analysis, full-wave modeling, link simulation, and hardware measurement validation.