Design of a Cable Measurement Fixture Based on 2X-Thru De-embedding Techniques

Abstract The design of a fixture and methodology for evaluating the performance of a cable is presented in this study. The objective is to improve the production yield rate, ultimately improving the quality management process. The 2X-Thru de-embedding method is employed for a quick and straightforward extraction of wire characteristics. The fixture incorporates a pogo pin, which provides a junction between the fixture and the wire. The pogo pin features a flat head, which effectively reduces signal reflection. Due to skin effect, we can assume that the current flow is limited to the surface of the pogo pin, neglecting the impact of the inner spring at high frequencies. Measurements using a time domain reflectometer are conducted to validate the repeatability and reproducibility predicted by the fixture three-dimensional modelling. The proposed fixture consists of a coplanar waveguide with ground (CPWG) structure. A pogo pin is soldered onto the printed circuit board (PCB) pad. The characteristic impedance of the fixture is measured using a time domain reflectometer to confirm its impedance matching capabilities. Additionally, we verify the fixture's symmetry using 2X-Thru de-embedding techniques while also characterizing the bulk wires. Our design demonstrates excellent durability and precision, making it a promising solution for high-speed cable signal measurement applications. It is highly suitable for cable quality inspection in industrial, automotive and medical fields.