Semiconductor Electronics — Practice

Question 1

In a CE amplifier beta = 100 and I_B = 40 uA. Find I_C and I_E.

Accepted Answer

I_C = beta I_B = 100 x 40e-6 = 4 mA. I_E = I_C + I_B = 4.04 mA.

Question 2

What is the ripple frequency of a full-wave rectifier with 50 Hz input?

Accepted Answer

100 Hz, since both half-cycles contribute, giving twice the input frequency.

Question 3

Identify the gate whose output is 0 only when both inputs are 1.

Accepted Answer

A NAND gate (Y = NOT(A.B)).

Question 4

A Zener regulator has V_Z = 5 V, R = 500 ohm, input 8-12 V. Find the resistor current range.

Accepted Answer

I_R = (V_in - V_Z)/R. At 8 V: 3/500 = 6 mA. At 12 V: 7/500 = 14 mA. The Zener current adjusts within this range to hold 5 V.

Question 5

Why is the n-p-n transistor more commonly used than p-n-p?

Accepted Answer

In an n-p-n transistor the majority carriers are electrons, which have higher mobility than holes, giving faster operation and better performance.

Practice — Semiconductor Electronics