Analysis of the PDN Induced Crosstalk Impacts on the High-Speed Signaling in Ultra-Thin and High Permittivity Substrates

In this paper, we conduct analysis of the power delivery network (PDN) induced crosstalk impacts on the high-speed signaling in ultra-thin and high permittivity substrates. When the PDN impedance is high, the return current discontinuity occurs in signal via transition and causes noise through power/ground planes. Therefore, to reduce the PDN impedance, although the decoupling capacitors are used in printed circuit board (PCB) design, the effective bandwidth and design space have limits. Meanwhile, the ultra-thin and high permittivity substrate has capability of reducing the PDN impedance in the wideband. Using electromagnetic (EM) and circuit simulations, we compared the crosstalk impacts by analyzing the insertion loss, PDN impedance, and eye diagram in three substrates. The eye diagrams were simulated under the situation that the clock signal with data rate (DR) that corresponds to the frequency of (1,0) mode of PDN on an aggressor, which is ten times line width away from a victim. We compared the eye-opening voltage and power/ground noise amount among with/without aggressor and each DR of victim. As a result, we found that the ultra-thin and high permittivity substrate can significantly suppress the PDN induced crosstalk impacts compared to the conventional flame-retardant type 4 (FR-4) substrate. In addition, because the PDN impedance is reduced in the wideband, these substrates can provide a good return path for signal vias in any position mounted on the PCBs and are helpful for various issues related to the PDN impedance.