Calibration and characterization techniques for on-wafer device characterization

In this contribution we review the challenges and possible solutions to achieve accurate s-parameters and power calibration in the (sub)mm-wave bands. A numerical and experimental analysis of multimode propagation over co-planar transmission lines, used during the calibration process, is described. The losses and coupling effects arising from the unwanted propagating modes are analysed by means of 3D electro-magnetic simulations. Fused silica is then proposed as an optimal calibration substrate due to its low loss-tangent and low dielectric constant, which allows to reduce, compared to alumina, losses arising from spurious modes. Experimental data of probelevel calibration performed in the 220-325GHz band are presented. A frequency scalable approach to achieve absolute power control for large signal characterization in the (sub)mm-wave bands is introduced. The proposed hardware configuration employs only a commercially available VNA and the required frequency extenders to cover a given band and does not employ expensive additional test-sets. Measurement results are provided in WR-10, WR-05 and WR-03 waveguide bands to report the scalability of the method.