GaN HEMT/Si MOSFET Hybrid Switch With Suppressed Dynamic ON-Resistance and Enhanced Avalanche Robustness

In this work, a GaN/Si hybrid power switch is proposed to overcome the disadvantages of dynamic ON-resistance degradation and limited avalanche capability for pure-GaN switches. The proposed hybrid switch exhibits suppressed dynamic ON-resistance, increased power conversion efficiency and enhanced avalanche robustness when compared to the pure-GaN switch with exactly the same ratings. By employing an active gate control pattern between GaN and Si devices within the hybrid switch, the dynamic ON-resistance is significantly reduced by more than 20%. Consequently, it increases the efficiency by 2% in a 48-to-24 V DC-DC buck converter at the switching frequency of 500 kHz and an output power of 240 W. The single-event avalanche energy withstanding capability shows a two-order-of-magnitude improvement and no failure is observed after a 1000-cycle repetitive UIS (Unclamped Inductive Switching) test.