Tribhuvan University
Institute of Engineering
Examination Control Division
2070 Chaitra – Regular
Subject: Electronic Devices and Circuits (EX501)
Programme: BEL, BEX, BCT
Full Marks: 80
Pass Marks: 32
Figures in margin indicate Full Marks
(There may be minor errors while typing the questions. Please leave comment if any typos)
- What is p-n junction diode? Explain the large signal models of p-n junction diode. [1+4]
- Find the value of dynamic resistance if voltage in the diode is 650mv and Irs is 10pA = (10*10^-12A). Given n=2 and V1=25mV. [5]
- Why common collector amplifier is also called emitter follower? Draw the common collector transistor amplifier circuit and find its input impedance, output impedance and voltage gain. [8]
- Draw and describe the Ebears Moll model for BJT. [4]
- Describe in brief the operation of BJT as a switch in cut off and saturation region. [4]
- Describe the construction and working principle of EMOSFET with help of drain characteristics curve and mathematical expressions.
- Find Id and Vds for the given circuit. The given data are: Vp = -4V and Idss = 10mA [5]
- Derive an expression to obtain the transconductance of JFET. [3]
- What is the maximum efficiency of class B amplifier? State the condition when it occurs. [4]
- When are tuned amplifiers used? Draw class A tuned amplifier circuit and find its 3db bandwidth. [2+5]
- Draw the circuit diagram of Complementary-Symmetry Class-AB amplifier. Using Darlington pair transistors. [3]
- Write the applications of tuned LC oscillators. Draw the Colpitt’s oscillator circuit and derive the expression for frequency of oscillation. [6]
- Draw AMV circuit using IC 555 or BJT. [4]
- State Barkhausen Circuit for sin wave oscillator. [2]
- Design a (10-25) V variable dc series voltage regulator using LM 317 IC. [5]
- Draw the circuit of current limiting circuit in dc voltage regulator. [2]
- Find voltage stability factor of series dc voltage regulator. [5]
