Error Term Analysis in 16-Term Calibration: Enhancing SiGe HBT S-Parameter Accuracy up to 330 GHz

This paper discusses the challenges involved in characterizing high-frequency SiGe HBT transistors. Process engineers continually strive to enhance device performance by shrinking dimensions and minimising parasitic capacitances; however, these capacitances—on the order of only a few femtofarads—are particularly susceptible to measurement errors. Moreover, commercial RF probes often guide electromagnetic fields inefficiently, inducing substrate coupling and crosstalk that further degrade measurement accuracy. To investigate these issues, we apply on-wafer 16-term calibration techniques using accurately designed calibration standards. Starting from the full 16-term error-correction model and progressively simplifying it in a step-by-step manner, we compare the performance of 16-, 10-, and 8-term calibrations and, finally, traditional TRL calibration up to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$330 \text{G H z}$</tex>. We verify the consistency of these approaches, analyse their influence on the extraction of passive elements, and evaluate how each calibration scheme affects key transistor performance metrics, such as the maximum oscillation frequency <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(f_{\text{max }})$</tex>.