A PCB Based High Resistance GHz Bandwidth Voltage Pick Up for Detecting Switching Voltage

The sub-nanosecond switching of GaN transistors at high voltages challenges existing methods of transient voltage measurement. A novel printed circuit board based implementation of a capacitively compensated resistive divider is presented in this paper. The geometry balances capacitive coupling to the high voltage side with capacitive coupling to ground and longitudinal capacitances along the resistors by symmetry. Using five 2 watt resistors a 3 GHz bandwidth is achieved at 5 KOhm. An equivalent circuit derived from the geometry and the full-wave model are validated by measurements.