(Editor’s note: check out the full article, “The fundamental advantages of D-Mode GaN in cascode configuration,” and get the full technical story behind these “busted” myths.)
Reality: When switching from reverse conduction to off-state, the reverse recovery charge accounts for not only bipolar transport minority carriers recombination but also the formation of the space-charge region, which is effectively equivalent to the output charge (Qoss). It’s true that GaN HEMTs have no reverse conduction bipolar transport, but they nevertheless do have output capacitance that needs to be charged during reverse recovery. In a nutshell, Qrr = Qoss. Qrr cannot be zero. Myth busted!
Myth #1: Si MOSFETs add-on state resistance reverse recovery charge
Uncover what chip really handles the majority of off-state high voltage — and which one contributes less than 10 percent of the total cascode resistance.
Myth #3: Cascode GaN oscillates
Read how following standard design principles enhances performance and suppresses oscillations and EMI.