Characterization and analysis of vertical coupling impact on receiver performance in high speed serial interface

As data rate increases, crosstalk becomes a significant source of high jitter. Although many techniques have been investigated to reduce crosstalk, it is not possible to fully eliminate coupling. In particular, near-end coupling between transmitter (TX) to receiver (RX) occurs at the interface of chip and PCB is one of the main sources of crosstalk. This TX to RX coupling is detrimental compared to other TX to TX or RX to TX coupling since the aggressor TX swing is large and the victim RX signal has slow edge. Thus, RX jitter is sensitive to coupling noise from TX. Therefore, it is important to investigate crosstalk impact on receiver performance on the system level including transmitter, receiver, package and PCB. In this paper, the impact of transmitter to receiver crosstalk induced at package balls and PCB vias is characterized using the internal eye-monitoring circuits. Critical factors causing this near-end crosstalk are identified and analyzed.