Capacitive crosstalk compensation structure for improved high-speed on-package signaling

This paper explores the effectiveness of under-bump comb (UBC) structure to address the capacitive crosstalk couplings in high-speed on-package interconnects applications. Three-dimensional (3D) passive electrical models were established and simulated in this assessment. Transient analyses were conducted to compare the far-end crosstalk (FEXT) profiles and eye diagrams of the UBC and conventional package routing designs. Simulation results shows the UBC design is able to reduce the peak-to-peak FEXT magnitude by >30% at 8Gbps and delivers up-to 20mV/3ps eye margin improvement compared to conventional design. The sensitivity of the UBC design parameters e.g. fin-count and fin-length correspond to electrical performances such as eye diagram opening, signal overshoot and undershoot are also included in this paper for design optimizations.