Effect of via-transitions on signal integrity using power transmission lines

Transmission lines carrying high-speed I/O signals that traverse through different metal layers in a printed circuit board suffer from return path discontinuities. As a result, significant amount of electromagnetic energy can couple to surrounding circuits and the power distribution network. In this work, we designed three printed circuit board (PCB) test vehicles using different power distribution topologies. One of them was based on a recently proposed power delivery method using power transmission lines (PTL). The other two were designed according to conventional power-ground plane pair approach. We show through measurement that PTL-based design provides less than -40dB of crosstalk between a signal line with multiple via-transitions and a nearby victim line. Measured data also showed that the PTL-based test vehicle had more than 68% of power supply noise reduction as compared to conventional designs.