Characteristic Impedance Deembeding of Printed Lines with the Probe-Tips Calibrations

The procedures allowing determination of the microstrip and CPW lines characteristic impedance are presented. The procedures are based on the measurement technique of two on-wafer line standards as presented by Carchon et al (1). An initial off-wafer LRM or TRL calibration is assumed. The formulation of the whole extraction problem in terms of the ABCD chain matrix allows us to omit the influence of a difference between complex characteristic impedances of both lines on the S-matrix asymmetry of the feeding transition. On the contrary, the AD-BC=1 condition of its chain matrix is not influenced by this effect. The next novelty lies in the modelling of the CPW-microstrip transition by a symmetric model. This allows to extract the characteristic impedance without using of any fixed transition model and takes automatically into consideration a distributed nature of the transition. The next feature is that a specific treatment of the measured standards enables to extract an equivalent position of the probe-tips along the line. In case of MCM-D different microstrip feed topologies have been analysed and the best possible one has been found.