In this study, we demonstrated a dual-gate enhancement/enhancement E/E-mode and enhancement/depletion (E/D) mode AlGaAs/InGaAs pHEMTs technology for high voltage and high power amplifier application. The dual-gate devices shows the higher breakdown voltage (V{sub}(br)) and maximum oscillator frequency f{sub}(max)) due to two depletion regions can also share total electrical field in the device so that the higher output resistance (R{sub}(ds)) and lower gate-to-drain capacitance (C{sub}(gd)) can be obtain. Therefore, the dual-gate device can be operated at higher drain-to-source voltage (V{sub}(ds)) to obtain excellent linear gain and output power performance as compared with conventional single-gate E-mode device. The maximum oscillation frequency increases from 78 GHz to 123 GHz under V{sub}(ds) = 4V biasing for single gate the E-mode and dual-gate E/E-mode device and the rf maximum output power increases from 636 mW/mm to 810 mW/mm under a 2.4 GHz operation for single gate the E-mode and dual-gate E/D-mode device, respectively And, we also demonstrated a 2.4 GHz ultra-high gain and high power density two-stage power amplifier using dual gate E/E and E/D-mode transistors, where the E/E-mode pHEMTs for gain-stage, and E/D-mode pHEMTs for power-stage, respectively, The linear gain of 40 dB and maximum output power of 24 dBm were obtained at V{sub}(ds)= 4 V I{sub}(ds) = 30 mA 0.5-μm (gate length) × 2 (fingers) × 75-μm (gate width), and V{sub}d = 9 V I{sub}(ds) = 100 mA for 0.5 × 8 × 75-μm{sup}2 E/D-mode pHEMTs respectively.
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