A GaN-based currrent sense amplifier for GaN HEMTs with integrated current shunts

This work shows a GaN-based current sense amplifier as a read out circuit for a power GaN HEMT with integrated current shunt. In the GaN power transistor, the voltage drop of the outermost metal finger of a large-area comb structure effectively realizes a shunt acting as a current sensor. This small voltage drop of the integrated shunt (approx. 4 mV/A at 100 mOon-resistance) is amplified by a two-stage GaN-based amplifie rwith a gain of >40 dB at room temperature. The amplifier consisting of two series-connected differential amplifiers with source follower intermediate stages was verified in a double pulse test setup up to a peak current of 11.5 A. Consequently, the proposed current sense amplifier allows a simple and potentially integratable further processing for the monitoring or control ofthe current signal.