Assembly Influence on the Small-Signal Parameters of a Packaged Transistor

A detailed analysis of the assembly influence on thesmall-signal parameters of a packaged transistor is presented. A newmethod, based on 3D field simulation and mixed-mode scatteringparameters approach is proposed. Differences in scattering parameterscaused by assembly change are computed using the new proposed methodand compared to the standard method based on admittance matrix. Thedifferences, accuracy, error sources and suitability of both methodsare discussed. Results are verified experimentally in microstrip linefor two fundamental assembly changes of a transistor in SOT 343 packagein frequency range 45 MHz - 18 GHz.