Perspectives on GaN MISHEMT Power Amplifier Versus Positive Gate Bias Instability

In this work, we discuss whether a positive gate bias instability $(\Delta \mathrm{V}_{\mathrm{t}\mathrm{h}})$ issue hampers a G$a$N MISHEMT in power amplifier (PA) applications. Two aspects are evaluated: (1) the safe gate modulation range of a GaN MISHEMT that is free of $\Delta \mathrm{V}_{\mathrm{t}\mathrm{h}}$, and (2) the gate modulation range of a PA in linear operation. The analysis shows that the two ranges have a significant overlap, meaning that a linearly operating MISHEMT PA can be well designed to avoid the positive $\Delta \mathrm{V}_{\mathrm{t}\mathrm{h}}$ issue.