4-8 GHz Low Noise Amplifiers using metamorphic HEMT Technology

This paper describes two metamorphic high electron mobility transistor (mHEMT) amplifiers with low noise in the frequency band 4-8 GHz. One amplifier contains the complete circuitry on a monolithic microwave integrated circuit (MMIC) chip and the other is configured with the input network on a low loss duroid substate together with an MMIC. The measurements at room temperature for the MMIC gave a gain of 28plusmn1 dB and a typical noise temperature of 56 K. The measurements at room temperature for the hybrid-MMIC gave a gain of 29plusmn2 dB and a minimum noise temperature of 41 K. When cooled to 20 K the hybrid-MMIC obtained a minimum noise temperature of 6 K. The hybrid-MMIC is compared to InP based hybrid LNAs at cryogenic temperature