Modelizacion y utilizacion de spd para sintesis de muy bajo ruido banda L

Abstract

A state of the art low noise cryogenic amplifier for L-band radio astronomy applications is presented. It was implemented in hybrid MIC technology using commercially available chip HEMT transistors. The average noise temperature in the band (1.2-1.8 GHz) is 4.5 K (0.06 dB N.F.) and the minimum is 4 K. The gain is more than 35 dB over the band and good input reflection and stability is achieved. The amplifier is cooled at 15 K using a closed cycle helium refrigerator. The special measuring technique used for accurate cryogenic characterization is briefly described.