A Two-Port Measurement With Mechanically Robust Handhold Probes for Ultra Low PDN Impedance

Measuring the input impedance of a power distribution network of a high-speed printed circuit board is challenging because the port is defined on multiple vias, and the impedance can be below a milliohm. A mechanically robust probe, and a specially designed, low-inductance probe landing pad are designed to measure the power distrubtion network impedance. The measurement is based on a two-port measurement method, and the mutual inductance of the port, which is the main source of error of the method, is characterized. Comparison between measurement and full-wave simulation shows that the presented probes and fixtures are suitable for measuring impedance in the sub-milliohm range.