The V_CC bypass capacitor provides the gate charge for the low-side and high-side transistors and absorbs the reverse recovery charge of the bootstrap diode. The required bypass capacitance can be calculated with Equation 1.

Q_G is the individual and equal gate charge of the high-side and low-side GaN FETs. Q_RR is the reverse recovery charge of the bootstrap diode. ΔV is the maximum allowable voltage drop across the bypass capacitor. A 0.1-µF or larger value, good-quality, ceramic capacitor is recommended. Place the bypass capacitor as close as possible to the VCC and AGND pins of the device to minimize the parasitic inductance.