Multiport measurement and deembedding techniques for crosstalk study in via arrays

In this paper the authors present techniques for crosstalk measurements in via arrays using broadband microprobes and a multiport vector network analyzer. The desegmentation method is used for probe deembedding in the bandwidth from 10 MHz up to 50 GHz. In contrast to the common approach which relies on T-matrices the desegmentation procedure ensures flexible fixture extraction using directly the S-parameter or Z- parameter matrices of the multiport network that has to be deembedded. The main advantage of the deembedding by desegmentation technique is that it does not require any S- to T-parameters conversion and if desired allows stepwise extraction of the embedded error networks. A typical application of the desegmentation method is presented by the authors where in the case of microprobe based measurement the error boxes of the microprobes are obtained at first by the use of a two-tier calibration technique and in the next step the desegmentation is applied to remove their detrimental effect on the measurement data.