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

p-GaN HEMTs are favored for bridge topology applications where they act as the freewheeling transistors to commute the current during the dead time. However, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_DS</i> , <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v_DS</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v_GS</i> oscillations at this period are observed and may introduce EMI problems. In this paper, 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 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_G</i> . 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 anti-parallel 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 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_DS</i> is reduced by 60% with 1% chip area of LR. Meanwhile, the high switching speed of the p-GaN HEMT is not affected.