Development of GaN Transducer and On-Chip Concentrator for Galvanic Current Sensing

Gallium nitride (GaN) magnetic high electron mobility transistors (MagHEMTs) with different gate lengths intended for integration with magnetic flux concentrator for galvanic isolation are presented. Detailed discussions on the physical mechanisms behind the sensitivity change at room temperature with respect to gate geometry are given. The relative sensitivity of dual-drain GaN MagHEMTs with a device length of ${L} = {65}\,\,\mu \text{m}$ and a width of ${W} = {20}\,\,\mu \text{m}$ is measured at the highest of ${S} = {17.21}$ %/T and the lowest of ${S} = {7.69}$ %/T at ${V}_{{\text {GS}}}= -{2}$ V and ${V}_{{\text {GS}}}= {0}$ V, respectively. In addition, a novel spiral magnetic flux concentrator with the conversion factor of up to ${F}_{C}= {96}$ mT/A is designed for improving the performance of the optimized MagHEMTs in ICs. It is predicted that a spiral configuration is a necessity to enhance the conversion factor for a long MagHEMT.