A Monolithic 3.5-to-6.5 GHz GaAs HBT-HEMT/Common-Emitter and Common-Gate Stacked Power Amplifier

This letter describes a monolithic 3.5-to-6.5 GHz stacked power amplifier (PA) in 2 mu m/0.5 mu m GaAs HBT-HEMT process. The proposed PA is designed using both HBT and HEMT. Based on a common-emitter (CE) configuration of HBT with a stacked common-gate (CG) configuration of HEMT, a better power performance of 3 dB improvement can be achieved as compared with the conventional CE or common-source amplifier due to high output stacking impedance. By using the proposed method, the stacked PA demonstrates a maximum output power of 29.4 dBm, a compact chip size of 1.5 x 1 mm(2), and a maximum power added efficiency (PAE) of 38%. The output power of the proposed PA is higher than 26.5 dBm between 3.5 and 6.5 GHz.