Cryogenic Ultra-Low Noise Amplification - InP PHEMT vs. GaAs MHEMT

We present a comparative study of 130 nm high electron mobility transistors (HEMTs) fabricated on pseudomorphic InGaAs/InAlAs/InP (InP PHEMT) and InGaAs/InAlAs/GaAs (GaAs MHEMT) intended for ultra-low noise amplifiers (LNAs). The epitaxial growth, as well as the HEMT process, was performed simultaneously. When integrated in a 4-8 GHz 3-stage LNA at 300 K, the measured average noise temperature was 34 K for the GaAs MHEMT and 27 K for the InP PHEMT. When cooled down to 10 K, the InP PHEMT LNA was improved to 1.6 K, while the GaAs MHEMT LNA was only reduced to 5 K. The reason for the superior cryogenic noise performance of the InP PHEMT compared to the GaAs MHEMT in this study, was found to be a higher quality of pinch-off when cooled down