Questions. $(3$ points each for $15$ points$)$

a$)$ Explain why the BJT is named the way it is based on its fabrication and operation.

b$)$ Why is the key feature of a transistor that makes it so useful?

c$)$ What are the $3$ regions used for the large$-$signal model of a BJT$?$

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d$)$ When use in forward$-$active mode, the transistor$$s output behavior mimics what dependent circuit element?

e$)$ What is the difference in application between the small$-$signal model and the large$-$signal model in amplifiers?