| Summary: | 碩士 === 國立臺灣科技大學 === 工程技術研究所 === 82 === A theortical study of a.c. capacitance of bipolar devices, such
as p-n junction diode and bipolar junction transistor, has been
made. Firstly, we present a theory for the voltage distribution
of the applied voltage across a p-n junction diode. In the
theory , we allow for the voltage drops formed by the gradient
ofmajority carrier concentration and quasi-Fermi levels in
quasi- neutral region, According to the theory, we derive new d.
c. and a.c. equivalent circuits for p-n junction diode, by
which we can calculate device characteristics at any injection
level, Secondly , we extend the diode theory to bipolar
junction transistor and investigate the d.c. current-voltage
characteristics and the a.c. capacitance of emitter-base
junction of a BJT worked at forward active region, We find that
the a.c. capacitance increases withincreasing bisa initially,
and then drcreases to negative value. The simulation results
are qualitatively similar to those of experiments.
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