A K-Band GaN MMIC Series-Connected Load Doherty Power Amplifier

This paper presents the design of a Monolithic Microwave Integrated Circuit (MMIC) series-connected load Do-herty Power Amplifier (S-DPA) for K-band wireless applications. Design steps will be described highlighting S-DPA performances using a GaN/SiC technology at high frequency. From this point of view the S-DPA has been realized in the 0.15 mu m gate length Gallium Nitride on Silicon Carbide (GaN/SiC) HEMT technology available at WIN Semiconductor foundry. A preliminary experi-mental characterization in linear regime shows a good agreement between measured and simulated performance, demonstrating a gain better than 14 dB with both input and output return losses better than 8 dB from 19 GHz to 20 GHz, frequencies which have not been investigated with a S-DPA configuration before this work. Expected nonlinear performance at saturation are about 36 dBm of output power with 33 % of power added efficiency and 13 dB of associated gain at center frequency. The efficiency remains larger than 23 % over 6 dB of output power back-off.