Comparison of enhancement- and depletion-mode triple stacked power amplifiers in 0.5 µm AlGaAs/GaAs PHEMT technology

This paper describes triple stacked power amplifiers using 0.5 mum enhancement- and depletion-mode (E/D-mode) AlGaAs/GaAs pseudomorphic high electron-mobility transistors (PHEMTs). Based on the optimum capacitance at the gate termination of common-gate (CG) transistor, the output 1-dB compression points (P_1dB) of the E- and D-mode triple stacked power amplifiers are 22.1 and 19.3 dBm, respectively. The third-order output intercept point (OIP₃) of the E- and D-mode stacked power amplifiers are higher than 32 and 25 dBm, respectively. The E-mode stacked power amplifier demonstrates better output power and linearity as compared with the D-mode stacked power amplifier due to the device characteristics. Moreover, the comparison between the E- and the D-mode tacked power amplifiers is also presented.