Monolithic Integration of p-GaN HEMT With Antiparallel Lateral Rectifier to Reduce the Negative Resistance Effect

p-GaN high electron mobility transistors (HEMTs) are favored for bridge topology applications where they act as the freewheeling transistors to commute the current during the dead time. However, the ${{i}_{DS}}$, ${{v}_{DS}},$ and ${{v}_{GS}}$ oscillations at this period are observed and may introduce electromagnetic interference problems. In this article, we have demonstrated the presence of the negative resistance effect in p-GaN HEMTs by small signal analysis and revealed the origin of the abovementioned oscillations. The negative resistance comes from the unique reverse conduction mechanism of p-GaN HEMT and strengthen the oscillation of the driving current ${{i}_G}$. According to the derivation formula of the negative resistance, it can be reduced by paralleling a resistor between the drain and source of the freewheeling transistor. Thus, an antiparallel lateral rectifier (LR) is monolithically integrated with the p-GaN HEMT to reduce the negative resistance. A synchronous buck converter was constructed to verify the effectiveness in a circuit-level application. The experiment results show that the negative resistance has a 11% reduction and the oscillation amplitude of the ${{i}_{DS}}$ is reduced by 60% with 1% chip area of LR. Meanwhile, the high switching speed of the p-GaN HEMT is not affected.