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Amplifier Bias for Minimum Noise Figure in Thermally Constrained Systems
Publikationstyp
Conference Paper
Publikationsdatum
2021-04
Sprache
English
Institut
Start Page
281
End Page
284
Citation
51st European Microwave Conference (EuMC 2021)
Contribution to Conference
Publisher DOI
Scopus ID
2-s2.0-85133013545
The noise figure of low noise amplifiers (LNAs) critically depends, amongst others, on the biasing conditions and the transistor temperature. The latter may be constrained by the performance of the cooling system, in particular its thermal resistance, and the ambient temperature. This paper reports as a case study how the noise figure can be minimized in such constrained systems by properly adjusting the biasing conditions. For this, the two-dimensional noise figure dependence on the temperature and the drain current is measured for a commercial LNA. For a systematic mathematical treatment, the measured data are interpolated by means of two black-box models. In contrast to the first one, which requires the noise figure to be measured in a climate cabinet, the second one only necessitates room temperature data in addition to commonly available data sheet values. It is shown, that, depending on the thermal resistance of the cooling system and the ambient temperature, i.e., two constraining system parameters, an optimal drain current setting may reduce the dissipated power by up to about 50 % compared to the nominal data sheet value. As this lowers the heat load and, in turn, the device temperature, the noise figure can be improved by up to 0.4 dB.
Schlagworte
Adaptive biasing
low noise amplifier (LNA)
noise figure
self heating
thermal management