Question

Consider a p-n junction as a capacitor, formed with p and n material acting as thin metal electrodes and depletion layer width acting as separation between them. Based on this, assume that an n-p-n transistor is working as a amplifier in CE configuration. If $C_1$ and $C_2$ be base-emitter and collector-emitter junction capacitances, then

• A. $C_1>C_2$
• B. $C_1<C_2$
• C. $C_1=C_2$
• D. $C_1=C_2=0$

Answer 1

The correct option is A $C_1>C_2$

Here, a n-p-n transistor is working as an amplifier in CE configuration. Hence, first junction n-p is forward biased and second junction p-n is reverse biased. The separation between plates (depletion region) depends on forward and reverse voltage. Thus, their capacitance $C_1$ and $C_2$ depends on the applied voltages.
Hence, $C_1>C_2$