Simplified Design Approach for Via Transitions up to 67 GHz
Abstract
A systematic approach for high-speed via transition design is proposed. The effects of via barrel radius, anti-pad size, and the distance from adjacent stitching (GND) vias on bandwidth are analyzed and characterized. Guidelines for selecting parameter values are provided and validated by correlating 3D full-wave FEM simulation results with actual measurements of the coupon board. When a sufficient number of stitching vias are used, the via structure can be approximated as a coaxial transmission line. The proposed methodology builds on this approximation and also considers high-order modes. With this framework, engineers can easily optimize design parameters while intuitively understanding how geometry affects bandwidth. This approach also allows engineers with limited access to expensive and computationally intensive 3D FEM tools to design high bandwidth vias up to 67 GHz.