Evaluation of CMOS differential transmission lines as two-port networks with on-chip baluns in millimeter-wave band

It is difficult to evaluate four-port on-chip CMOS devices in the millimeter-wave (MMW) band using four-port vector network analyzer. To obtain the differential-mode characteristics, we proposed the technique of evaluating four-port networks as two-port networks using on-chip baluns, and applied the technique to the evaluation of differential transmission lines in the MMW band. As a result, it was shown that the propagation constant of the differential mode obtained by this technique was in the good agreement with one obtained by the EM simulation at the frequency band from 47 GHz to 110 GHz. By using this technique, it is expected that on-chip CMOS differential devices in the MMW band can be evaluated more easily.