Characteristics of low noise 800MHz amplifier at cryogenic temperature

Low noise amplifiers (LNA) have been designed and developed with high performance at cryogenic temperature in CDMA superconducting receiver front end. The low noise amplifier has been characterized at liquid nitrogen temperatures. The frequency band is in the range from 780MHz to 880MHz using Agilent PHEMT which has low noise figure at cryogenic temperatures. The components were implemented with lumped elements, which can make the LNA for the miniaturization and reduce the load consumption of the cooler. In the frequency band of operation at 60K, the achieved noise figure (NF) is within 0. 3 dB from the minimum NF of a single transistor, the power gain is about 17 dB, flat is within 1 dB, the maximum input VSWR/sub in/ and output VSWR/sub out/ are lower than 1.3 individually.