Measurement-Based Modeling of PCB-to-Coaxial Cable Transition for 3D Electromagnetic Simulation by Equivalent Circuit Assisted De-Embedding

This paper describes a procedure to generate a 3D model for electromagnetic simulation of the transition region, i.e. solder connection, between a printed circuit board (PCB) trace and a coaxial cable. The PCB-to-coax launch cannot be directly accessed by measurement, thus de-embedding is used to extract the section under investigation from measurements. However, de-embedding procedures like 2xThru, that require fixtures with low variances, are not suitable for this task due to considerable variation in solder joints and available test structures. Instead, de-embedding based on an equivalent circuit is proposed. The circuit is partitioned into physical meaningful sections, such that the 3D model of the targeted PCB-to-coax interface can be verified by comparison to respective parts of the circuit. S-parameters up to 26.5 GHz and time domain reflectometry (TDR) are used to validate the simulation model against measurements of multiple hardware samples.