Draw the tramsfer characteristic curve of a base biased transistor in CE configuration. Explain clearly how the active region of the `V_o" versus " V_i` curve in a transistor is used as an amplifier.

Explanation

(a)
In the active region, a (samll) increase of Vi results in a (large, almost linear) increase in `I_c`. This results in an increase in the voltage drop across `R_c`.
(b) When `V_i` becomes greater than 0.6 V, the transistor is an active state with some current. `I_c` in the output path. The transistor is operated as a switch. As long as `V_i` is low and unable to forward-bias the transistor, `V_0" is high. If "V_i` is high enough to derive the transistor into saturation, the `V_0` is low, very near to zero.
When the transistor is not conducting, it is said to be switched off and when it is driven into saturation,