A study of L-band GaAlAs/GaAs HBTs for high-voltage RF-power |
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| Authors: | T Johansson J Soderstrom L F Eastman D W Woodard |
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| Affiliation: | 1. Department of Electronic Science , University of Delhi , India anandvrm48@gmail.com;3. South Valley University , Qena , Egypt;4. Department of Electronic Science , University of Delhi , India;5. University of Magdeburg , Magdeburg , Germany |
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| Abstract: | The feasibility of GaAlAs/GaAs heterojunction bipolar transistors as power output transistors for 24–28V cellular base station applications was studied. A 1W, 25V test vehicle was fabricated, with predictable and uniform electrical parameters. Maximum output power was 1.02W with 9.1dB gain at 2GHz and 18V supply voltage. Characterization at more than 22V destroyed all devices, even if emitter ballasting resistors were used for thermal balance. Analysis indicated that the failures were caused by too wide emitters in combination with the high supply voltage, causing current crowding and large temperature spikes. Small (<2-3µm) horizontal emitter dimensions are required even with low base sheet resistivity, otherwise leading to destructive temperature non-uniformities, unless special arrangements to drastically reduce the thermal resistance can be applied. |
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| Keywords: | bandstop filter dual-band filter defected ground structure DGS filter |
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