L 波段宽带低温低噪声放大器的设计与测量*

高电子迁移率晶体管(HEMT)的小信号等效电路低温模型是研制致冷低噪声放大器(LNA)与研究晶体管微波特性的基础。该文通过测量HEMT 器件在低温环境下直流参数与散射参数(S 参数),构建了包含噪声参量的小信号等效电路,并据此设计了一款覆盖L 波段的宽带低温低噪声放大器(LNA),工作频率1 ~2GHz,相对带宽达到66. 7%。在常温下放大器功率增益大于28dB,噪声温度小于39K;当环境温度制冷至11K 时,噪声温度为1. 9~3. 1K,输入输出端口的回波损耗S11 和S22 均优于-10dB,1dB 压缩点输出功率为9. 2dBm,功耗仅为54mW。

Design and Measurement of L Band Broadband Cryogenic LowNoise Amplifier

The knowledge of the small-signal equivalent circuit cryogenic model of high electron mobility transistors(HEMT) is crucial for the design of cooled low-noise amplifiers(LNA) and is very useful to support the analysis of the transistor microwave performance. This paper describes a method for designing cryogenic L band amplifiers with very low noisefor the 1 ~2 GHz frequency range, the design is based on measured cryogenic direct current and scattering-parameters combined with a small-signal noise model. At room temperature, the HEMT amplifier achieved a power gain greater than 28dBand a maximum noise figure of 39K. When cooled to 11K, the noise temperature can be reduced to 1. 9 ~ 3. 1K, input andoutput return loss of better than -10dB, and 1dB compress point output power 9. 2dBm with a total power consumption of54mW.