研究目的
To investigate the cryogenic performance of radiation-hardened radio-frequency (RF) low-noise amplifiers (LNAs) utilizing inverse-mode silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) for extreme environment applications.
研究成果
The inverse-mode-based SiGe HBT LNA provides acceptable RF performance under cryogenic conditions for extreme environment applications, with comparable performance to conventional forward-mode designs. However, a noticeable gain reduction at 78 K was observed, attributed to the limited RF performance of inverse-mode SiGe HBTs. Mitigation approaches include device layout modifications, germanium profile optimization, and bias optimization techniques.
研究不足
The study observed a noticeable gain drop at 78 K in the inverse-mode LNA compared to the conventional forward-mode design, attributed to the limited high-frequency performance of inverse-mode SiGe HBTs at cryogenic temperatures. This indicates a potential limitation in the use of inverse-mode SiGe HBTs for cryogenic applications without further optimization.
1：Experimental Design and Method Selection:
The study involved the design and characterization of an LNA using inverse-mode SiGe HBTs for cryogenic operation. The methodology included the use of liquid nitrogen to cool the ambient temperature down to 78 K for cryogenic characterization.
2：Sample Selection and Data Sources:
The LNAs were fabricated using the GlobalFoundries 130 nm SiGe BiCMOS (8HP) technology. The SiGe HBTs used in the LNAs have the same (physical) emitter area of 120 nm x 2.5 μm for both forward and inverse mode operation.
3：5 μm for both forward and inverse mode operation.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: A custom-designed open-cycle cryogenic microwave probe station was used for cryogenic characterization. Measurement equipment included a two-port network analyzer (Agilent PNA E8361C), analog signal generators (Agilent PSG E8257), a spectrum analyzer (E4407B), and a noise source (Agilent N4002A).
4：Experimental Procedures and Operational Workflow:
The LNAs were measured in a cryogenic probe station with liquid nitrogen cooling. S-parameter, linearity, and noise figure measurements were conducted with appropriate calibrations at each measurement temperature.
5：Data Analysis Methods:
The performance of the LNAs was analyzed in terms of gain, noise figure, and linearity across different temperatures. The impact of inverse-mode operation on cryogenic performance was evaluated.
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