A 1.9 GHz SPDT switch implemented with GaN HFETs featuring two different depth-recesses in i-AlGaN

An i-AlGaN/GaN HFET structure with two different depth-recesses formed in the i-AlGaN layer is proposed for application to a 1.9 GHz SPDT switch. In the HFET structure, an ohmic contact is formed in the deep recess to reduce the contact resistance, and a Schottky gate is formed in the shallow recess to decrease the leakage current. The off-state capacitance of the HFET was 0.23 pF and the on-state resistance was 11 Ω at a gate length of 0.7μm and a width of 1 mm. An SPDT switch implemented with the HFETs was fabricated, and evaluated by on-wafer measurement. The maximum handling power was 34.7dBm at the device where the through FET width was 1 mm and the shunt FET width was 0.2 mm. A higher isolation than 21 dB and a low insertion loss of 1.1 dB were realized. This performance indicates that the proposed structure is promising for high-power and high-frequency RF switches.