No abstract

This work presents a Python-based driver for ANSYS HFSS for length matching elements (LME) implemented in Matlab. The driver allows full-wave EM parametric simulation of length matching elements, whose S-parameters are inserted in other circuit simulators, such as ADS, for a complete interconnect validation. Three different LME (i.e., trapezoidal, triangular, and rectangular) are analyzed using the driver in a common highspeed routing scenario. The driver proposed in this work allows verifying that the three LME considered have a similar performance up to 5 GHz, indicating that these LME can be used as mismatch (phase skew) compensation structures in some interfaces within this frequency band, such as USB 3.0, PCIe Gen3 or 1 GBASE Ethernet. On the other hand, the trapezoidal LME shows the best performance for frequencies higher than 5 GHz, with a low impact in the electromagnetic interference (EMI), making it the most recommended for high-speed interfaces with operating frequencies higher than 5 GHz.

Length matching elements (LME) are used for intra-pair length matching and inter-pair skew reduction to get high data rates in high-speed differential channels. Although these structures are widely used in printed circuit boards (PCB), the effectiveness of the structure depends on its geometry and dimensions, allowing different design alternatives. In this work, a novel LME for PCB designs is proposed. It is formed by three sub-structures, such that the insertion and impedance profile can be parametrically controlled by the geometry of the proposed LME without affecting the length matching. Mixed-mode parameters, extracted from simulation data, shows that the proposed LME presents lower insertion loss and less electromagnetic interference (EMI), than trapezoidal LME. In addition, time domain reflected analysis (TDR) shows better impedance profile for the proposed LME than for the trapezoidal shape. Both frequency-and time-domain results indicate that the proposed LME can be a good alternative for length matching compensation in high-speed channels.