Abstract
Owing to the demand of higher speed continues to increase in telecommunication industry, the differential pair is widely used in signal transmission. the issue in high-speed printed circuit boards (PCBs) that is crosstalk which was incurred by the coupling effect. In order to obtain good signal integral (SI) by minimizing the crosstalk between adjacent differential pair. That the output signal will not distortion is much important. As the transfer rate higher than 25 Gbps is needed. Minimizing the size of transmission line became an important issue because of limited area of the PCB. To overcome the challenges, this research proposed a spoof surface plasmon polariton (spoof SPP) structure of differential pair. This method not only can avoid using much space of PCB but also reducing the crosstalk noise. However, the crosstalk noise is serious because the frequency is higher and higher. We discuss the spoof SPP structure of differential pair for 100 gigabit/second transmission on low relative permittivity and low loss tangent PCB. The spoof SPP structure reduces the crosstalk at 70 GHz by the concept of spoof surface plasmon polaritons (spoof SPPs). It is found that the propagation frequency range of the unit-cell can optimize the geometric parameter. Numerical simulation is used to analyze the dispersion relation and the resonant frequency of unit cell and s-parameter of differential pair, then also compared with the conventional differential pair with the same size and separation. Hence the proposed spoof SPP differential pair can improve the crosstalk between the other typical differential pair, and the S63 parameter of crosstalk can smaller than -10 dB, that improved 2.7 dB.