Low Noise and Low Distortion Performances of an AlGaN/GaN HFET

摘要

We present ultra low noise- and wide dynamic range performances of an AlGaN/GaN heterostructure FET (HFET). An HFET fabricated on a high quality epitaxial layers grown on a semi-insulating SiC substrate exhibited impressively low minimum noise figure (NF_(min)) of 0.4 dB with 16 dB associated gain at 2 GHz. The low NF (near NF_(min)) operation was possible in a wide drain bias voltage range, i.e. from 3V to 15V. At the same time, the device showed low distortion character as indicated by the high third order input intercept point (IIP3), + 13dBm. The excellent characteristics are attributed to three major factors: (1) high quality epitaxial layers that realized a high transconductance and very low buffer leakage current; (2) excellent device isolation made by selective thermal oxidation; (3) ultra low gate leakage current realized by Pd based gate. The results demonstrate that the AlGaN/GaN HFET is a strong candidate for front-end LNAs in various mobile communication systems where both the low noise and the wide dynamic range are required.