A 145-ns Response Time High-Side Current Sense for a 100-V Monolithic GaN Half Bridge

This paper presents a monolithic GaN current sense circuit designed for the high-side of a 100-V half-bridge. The circuit is engineered to minimize current offsets and response times across a wide range of input voltages (10 V to 100 V), as well as varying temperatures and current loads. It is capable of tracking inductor current ripples and detecting the zero-current condition of the half-bridge high-side power transistor. The proposed solution demonstrates a simulated loop gain exceeding 100 dB and a bandwidth of 43.9 MHz, which achieves an accuracy of 99.4% and a response time of 145 ns under operating conditions of 50-V input voltage, 10-A current load, and 27°C.