A novel RF high-Q metal-semiconductor-metal planar inter-digitated varactor based on double-channel AlGaN/GaN HEMT structure

A novel GaN-based double-channel metal-semiconductor-metal configuration planar inter-digitated varactor, fabricated with a HEMT compatible process, is presented. Our varactors achieved high Q-factor, wide tuning range, and high minimum Q-factor (Q_min). The double-channel heterostructure extends the useful high Q-factor capacitance tuning range of the varactors. The operation of the varactor is explained by a physical equivalent circuit, in which the whole changing trend of extracted Q-factors over bias voltage and extracted resistance can be explained. The measurement results of the novel double-channel varactors are compared with varactors fabricated on a single channel heterostructure in order to show their superior performance.