Electrical performance of a multiport interposer for measurements of dense via arrays

In this paper the bandwidth limitations of two types of multiport probing fixtures for measurements of high density via array structures are investigated. Using a two-tier calibration technique and custom-made calibration substrates, error parameters for the probing fixtures were extracted and used to evaluate variability in measurements and substrate correction parameters. Results show adequate repeatability of the obtained error parameters up to 20 GHz. Digital links were measured utilizing these probing fixtures and results were compared to S-parameter measurements using RF microprobes. Good correlation up to 10 GHz - 15 GHz was established when compared to microprobe based measurements of link structures with stub access vias. For link structures with through access vias the adequate correlation bandwidth was founded to be 5 GHz - 10 GHz.