Mixed-mode S-parameter characterization of differential structures

Combined differential-mode and common-mode (mixed-mode) scattering parameters (S-parameters) are well adapted to accurate measurements of linear networks at RF and microwave frequencies. The relationships between standard S-parameters with two-port vector network analyzer (VNA) and mixed-mode S-parameters with four-port VNA are derived in this paper. An example differential structure was measured with standard two-port VNA and mixed-mode four-port VNA. The correlation of standard s-parameters and mixed-mode S-parameters is presented as well.