PCB-Integrated GHz Bandwidth Resistive Voltage and Current Probes for Characterization of Wide Bandgap Semiconductor Devices

Broadband (GHz) voltage and current sensors are required to measure the transient behavior of gallium nitride (GaN) devices due to their sub-nanosecond switching speed. In the case of asymmetric structures, achieving GHz bandwidth becomes even more challenging, even with traditional circular current probe designs. This article discusses the advantages and drawbacks of PCB-based resistive voltage and current probes, focusing on the tradeoffs between bandwidth and voltage pick-up resistance, as well as those between resistance and bandwidth in resistive current measurements. It also addresses the challenges and solutions for asymmetrical current sensor designs. A capacitively compensated resistive voltage divider (RVD) (3 GHz/5 k<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula>) is proposed, optimized through full-wave simulations, and validated with S-parameter measurements. Additionally, a shunt resistor composed of several parallel surface-mount device (SMD) resistors achieves 1.2 GHz/20 m<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> for the symmetric current sensor design and 1 GHz/5 m<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> for the asymmetric design, achieved through parasitic mutual inductance minimization. This article is an extended version of a work presented at EMC Europe 2023.