A low noise Ka-band amplifier for radio astronomy

We present the designs for and the results of a prototype cryogenic Ka-band low noise amplifier (LNA), that is based on the hybridization of microwave integrated circuits (MICs) and monolithic microwave integrated circuits (MMICs). The resulting transistor plus MMIC (T+MMIC) 5 stage LNA, has a peak gain of 52dB, a minimum noise temperature of 12K at an ambient temperature of ≈23K, and a 20% bandwidth of 27–33GHz. We outline the background behind the LNA, our measurement process, the LNA's performance, our future development plans and discuss the possible advantages that this amplifier layout may offer.