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A two stages cryogenic silicon-germanium heterojunction-bipolar-transistor(SiGe HBT)low-nose-amplifier(LNA)for 0.2-4GHz frequency range has been designed,fabricated andmeasured with the temperature range from 300K to 4K.Both of the stages of the amplifierutilize the commercially available plastic packaged SiGe transistors NXP BFU725F.Thetemperature dependent DC characteristics,namely current gain and trans-conductance of theSiGe transistor have been investigated.This amplifier achieves an averaged noise temperature aslow as about 10K with a gain over 30 dB for the frequencies in the range of 0.2-4GHz atphysical temperature of 4K.To verify the feasibility of the cryogenic SiGe LNA for astronomyobservation,we embedded the amplifier into a Superconductor-Insulator-Superconductor(SIS)receiver as the first stage IF amplifier and measured the performance of the receiver.We foundthat the receiver exhibited low noise without bringing any unexpected effect to the SIS mixer.Inaddition,the measurement result of receiver stability in term of Allan variance verified stableoperation at cryogenic temperature.Above results indicated that the SiGe LNAs based on thecommercially available transistors are applicable to radio astronomy observation.