S-Parameter De-embedding and TDR Accuracy at 145 GHz
Isolating connector performance from test fixtures requires flawless S-parameter de-embedding. Learn how to prevent mathematical artifacts from corrupting TDR simulation data.
Accurately measuring the signal integrity of a standalone high-speed connector requires isolating it from the physical test fixtures and cables used to connect it to an instrument. This process, known as S-parameter de-embedding, uses mathematical models to subtract the electrical characteristics of the test board traces from the overall measurement. However, at frequencies scaling up to 145 GHz, this math becomes incredibly sensitive.
Minor imperfections in the calibration standards or phase mismatches between test channels introduce non-causal errors and non-passive artifacts into the simulation matrix. When these flawed S-parameters are converted into Time-Domain Reflectometry (TDR) plots to analyze impedance profiles, the resulting graphs show artificial spikes and ghost reflections.
Engineers must utilize advanced algorithms, such as Thru-Reflect-Line (TRL) calibration and matrix-based fixture de-embedding, to ensure that the simulation data accurately reflects the physical connector geometry rather than mathematical noise.