Broadband characterization of a microwave probe for picosecond electrical pulse measurements

Abstract

The time-domain characterization of high-frequency devices with coaxial connectors requires the transfer of picosecond electrical pulses between coplanar and coaxial lines. Microwave probes are often used for this purpose. In this paper, the propagation of ultrashort electrical pulses over a microwave probe attached to a coplanar waveguide is experimentally studied by time-domain electro-optic sampling. From the experimental data, the attenuation and dispersion constants of the probe are determined up to 400 GHz. Moreover, the complex reflection and transmission coefficients of the junction between the microwave probe and the coplanar waveguide are extracted. Simple approximations are given for these quantities. These data can be used to predict the amplitude and shape of ultrashort electrical pulses after propagation over the microwave probe for arbitrary input pulses in the considered frequency range.