Electronic Devices and Circuits

Daffodil International University Faculty of Science & Information Technology Department of Computer Science & Engineering Midterm Examination, Fall 2026 Course Code: CSE215, Course Title: Electronic Devices and Circuits Level: 2 Term: 2 Batch: 69 Time: 01:30 Hrs Marks: 25 Answer ALL Questions [The figures in the right margin indicate the full marks and corresponding course outcomes. All portions of each question must be answered sequentially.] 1. a) Define Semiconductor. [1] CO1 b) Describe the temperature effect on Semiconductor. [1] c) Recall potential barrier in a pn junction. [1] d) Draw the circuit for common base connection of transistor. [1] e) Draw the symbol of npn and pnp transistor and specify the leads. [1] 2. a) Show that, β = α / (1 - α) [4] CO2 b) Explain the working principle of a full wave diode rectifier. [4] 3. a) Identify the maximum and minimum of Zener diode current for the given circuit below in fig.01. [4] CO3 [Figure: Zener diode circuit with variable DC input voltage 80 - 120 V, series resistor 5 kΩ, Zener diode 50 V, and load resistor 10 kΩ] fig.01 b) Construct a voltage stabilizer for varying load using two Zener diodes of 13V, which are connected in series. Series and load resistance are 3KΩ and 5KΩ respectively and the supply voltage is 40 V. [4] Solve the problem for (i) the output voltage (ii) the voltage drop across series resistance and (iii) the current through the Zener diode. c) For the common base circuit shown in fig.02, solve for, IC and VCB. Assume the transistor to be of silicon. [4] [Figure: Common base NPN transistor circuit with VEE = 8 V, RE = 1.5 kΩ, RC = 1.2 kΩ, and VCC = 18 V] fig.02