Small signal and power measurements of AlGaN/GaN HEMT with SiN passivation

Small signal S-parameters and loadpull measurements are reported for AlGaN/GaN HEMT devices with 200nm SiN passivation. The maximum output power increases from 0.59W/ mm to 1.45W/mm and the efficiency is also enhanced from 16 to 27% for 2x50 mum HEMT devices after SiN passivation. Small signal equivalent circuit parameters including parasitic and intrinsic ones have been extracted from the measured S-parameters and are used to explain the effect of SSI on the power characteristics.