This article describes a low noise amplifier which is believed will have a transformative impact because of the following characteristics: 1) the noise temperature at a physical temperature of 25 °C is a factor of 4 lower than typical commercial LNAs; 2) the noise decreases to 4.5 K at a temperature of −40 °C, a temperature realizable with solid-state coolers; 3) the LNA has an integrated, extremely stable noise source to facilitate measurement of system noise temperature; and 4) the amplifier is powered by a dc voltage and controlled by a tone signal on the RF output cable thus requiring no additional wiring. The amplifier benefits systems in the low microwave frequency range with low background temperature, such as those for space communications and radio astronomy, but without the capital and maintenance costs of cryogenic systems. This article describes the construction and test results with an emphasis on the manufacturability and accuracy of the noise measurements. Finally, the noise of a system deploying the LNA is described.

中文翻译：

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低噪声放大器，在1.4 GHz和25°C时具有7-K噪声

本文介绍了一种低噪声放大器，该放大器由于具有以下特性而被认为具有革命性的影响：1）物理温度为25°C时的噪声温度比典型的商用LNA低4倍；2）在−40°C（使用固态冷却器可实现的温度）下，噪声降至4.5 K；3）LNA具有集成的，极其稳定的噪声源，以方便系统噪声温度的测量；4）放大器由直流电压供电，并由RF输出电缆上的音频信号控制，因此不需要额外的布线。该放大器有益于低微波温度范围，背景温度低的系统，例如空间通信和射电天文学的系统，但无需低温系统的投资和维护成本。本文介绍了构造和测试结果，重点是噪声测量的可制造性和准确性。最后，描述了部署LNA的系统的噪声。