Silicon-Germanium Heterojunction Bipolar Transistors for Extremely Low-Noise Applications
Silicon-Germanium Heterojunction Bipolar Transistors for Extremely Low-Noise Applications
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适用于极低噪声应用的硅-锗异质结双极晶体管
DOI：
10.7907/mcpe-4m30
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
J. Bardin
中科院分区：
文献类型：
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作者：
J. Bardin
从历史上看，极低噪声固态放大的世界一直由奇异的技术主导，如InP和GaAsHEMTs。通过对这些器件进行低温冷却，有可能在几十年的带宽上实现噪声温度低至5K的微波放大器。尽管HEMTs在冷却到低温时可以提供非常低的噪声放大，但它们的辐射计性能受到固有跨导波动的限制。人们认为，双极器件不会出现这个问题。随着工业界在硅基技术上投入越来越多的资金，硅-锗(SiGe)异质结双极晶体管(HBT)不断改进，现在它们在微波低温低噪声放大器方面开始与InP HEMT竞争。尽管在低温下观察到了极高频率的器件工作，但对冷却的SiGe HBT的噪声建模工作却很少。在这份报告中，对使用硅-锗(SiGe)异质结双极晶体管(HBT)用于极低噪声应用的理论和实践进行了深入的研究。本论文分为三个部分：1)背景信息：介绍了SiGe HBT的基本原理，讨论了半导体在低温下的性质如何变化，以及这些变化对器件性能的影响。2)建模：在18~300K温度范围内对7种最先进的异质结双极晶体管进行了综合研究。从直流、小信号和噪声性能三个方面对这两种器件进行了比较，并提取了小信号噪声模型。本部分最后简要总结了有关低温下SiGe器件性能的重要结论。3)应用：将前面开发的模型应用于几种最先进的MMIC和离散形式的LNA的设计中。在低GHz范围内，噪声性能优于2K，可与最好的InP结果相媲美。这一部分最后讨论了最近制造的一些高阻抗差分放大器。
Historically speaking, the world of extremely low-noise solid-state amplification has been dominated by exotic technologies such as InP and GaAs HEMTs. By cryogenically cooling these devices, it is possible to realize microwave amplifiers with noise temperatures as low as 5K over decades of bandwidth. Although HEMTs can provide very low noise amplification when cooled to cryogenic temperatures, their radiometer performance is limited by intrinsic transconductance fluctuations. It is believed that bipolar devices do not suffer from this problem. As industry has invested more and more money into silicon based technologies, silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) have continued to improve and are now at the point where they are beginning to become competitive with InP HEMTs for microwave cryogenic low-noise amplifiers. Although extremely high frequency device operation has been observed at cryogenic temperatures, little work has been done on modeling the noise of cooled SiGe HBTs. In this report, a thorough investigation into the theoretical and practical aspects of using silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) for extremely low-noise applications is presented. The dissertation is broken up into three sections: 1) Background information: The fundamentals of SiGe HBTs are presented along with a discussion of how the properties of semiconductors change at cryogenic temperatures, as well the impact that these changes have on the performance of the devices. 2) Modeling: A comprehensive study of seven state-of-the-art HBTs at temperatures ranging from 18 K to 300 K is presented. The devices are compared in terms of dc, small-signal, and noise performance, and small-signal noise models are extracted. The section concludes with a brief summary of the important conclusions regarding the performance of SiGe devices at cryogenic temperatures. 3) Applications: The models developed previously are applied to the design of several state-of-the-art LNAs in both MMIC and discrete form. Noise performance better than 2 K is achieved in the low-GHz range, which is comparable to the best InP results. The section concludes with a discussion of some high-impedance differential amplifiers which have recently been fabricated.