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Draw typical output characteristics of an n-p-n transistor in CE configuration. Show how these characteristics can be used to determine output resistance. |
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Answer» Solution :Output characteristics is the plot between collector-emitter voltage `(V_(CE))` and the collector current `(I_(c))` at different constant values of base current `(I_(B))`. Output resistance is defined as the ratio of the change in collector-emitter voltage `(Delta V_(CE))` to the change in collector current `(DeltaI_(c))` at a constant base current `(I_(B))`.  Initially with the increase in `V_(CE)` the collector current increases almost linearly. This is because the junction is not reverse biased. When the SUPPLY is more than REQUIRED to reverse bias the base-collector junction, `I_(C)` increases very little with `V_(CE)`. The RECIPROCAL of slope of the linear part of the curve gives the value of output resistance i.e., `r_(0)=((Delta V_(CE))/(Delta I_(c)))I_(B)`. |
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