MPH C204
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shaktikashyap2022MPH C204
Uploaded by
shaktikashyap2022A&B
PAPER CODE: MPH-C204
SEMESTER EXAMINATION- MAY 2023
CLASS: M.SC. SEMESTER: II
PAPER TITLE: ELECTRONIC DEVICES & CIRCUITS
Time: 3 hour Max. Marks: 70
Note: Question Paper is divided into two sections: A and B. Attempt both the sections as per given
instructions.
SECTION-A (SHORT ANSWER TYPE QUESTIONS)
Instructions: Answer any five questions in about 150 words each. Each Q carries six marks.
(5 X 6 = 30 Marks)
Q-1: State Norton’s network theorem. Draw equivalent of the given circuit (Fig. 1) and calculate the
current in the load RL.
Fig. 1
Q-2: What is diode Limiter and clamper? Explain with circuit diagram.
Q-3: a) State and prove Miller’s theorem. What is its application?
b) Figure 2 shows an ac amplifier with a midband voltage gain of 200. If the cutoff frequencies
are f1 = 20 Hz and f2 = 20 kHz, what does the frequency response look like? What is the
voltage gain if the input frequency is 5 Hz?
Fig. 2
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Q-4: In an n-channel JFET biased by potential divider method, it is desired to set the operating point
at ID = 2.5 mA and VDS = 8 V. If VDD = 30 V, R1 =1 MΩ and R2 = 500 kΩ, find the value of RS.
The parameters of JFET are IDSS = 10 mA and VP = -5 V.
Fig. 3
Q-5: Give various types of differential amplifier. Discuss DC analysis of differential amplifier.
Q-6: What are lead and lag networks. Discuss the frequency response, cut off frequency, half power
point and stiff coupling in lead network.
Q-7: Write short notes on the following:
a) OP-Amp as Integrator
b) OP-Amp as summing amplifier
Q-8: What do you understand by voltage regulation? Discuss the working of transistor series voltage
regulator.
Q-9: a) Draw the equivalent circuit of UJT and discuss its working from the circuit.
b) The intrinsic stand-off ratio for a UJT is determined to be 0.6. If the inter-base resistance is
5 kΩ, what are values of RB1 and RB2?
Q-10: In the given circuit (Fig. 4), calculate currents in the branches AB, BC and BE, making use of
superposition theorem.
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Fig. 4
SECTION-B (LONG ANSWER TYPE QUESTIONS)
Instructions: Answer any four questions in detail. Each question carries 10 marks.
(4 X 10 = 40 Marks)
Q-1: a) Describe common emitter (CE) transistor amplifier and discuss its a.c. model.
b) In the following circuit (Fig. 5) the transistor has β = 50. Find the output voltage if input
resistance Rin= 0.5 kΩ.
Fig. 5
Q-2: a) What is zener diode? Draw the equivalent circuit of an ideal zener in the breakdown region.
Explain how zener diode maintains constant voltage across the load.
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b) A zener is used to regulate output voltage for which the load current varies from 12 mA to
100 mA. Find the value of series resistance to maintain a voltage 7.2 V across the load. The
input voltage is constant at 12 V and the minimum zener current is 10 mA.
Q-3: What is the difference between a JFET and BJT? Explain the construction and working of a
JFET. Also give its drain and trans-characteristics. When a reverse voltage of 15V is applied to
a JFET, the gate current is 10-3 μA. Find the resistance between gate and source.
Q-4: Describe non-inverting voltage feedback amplifier. Also discuss the effect of non-inverting
voltage feedback input and output impedances of an op-amp. In Fig. 6, the 741C has an open
loop gain of 100,000, Rin of 2 MΩ and an RCM of 200 MΩ. What is the closed loop voltage
gain and input impedance?
Fig. 6
Q-5: a) What is a 555 IC timer? Explain it’s working by its functional diagram, how is it used as
monostable multivibrator?
b) What will be the output voltage of an op-amp inverting adder for the input voltages V1 = -
10V, V2 = +10V, V3 = +5V and the resistances R1 =600 kΩ, R2 = 3000 kΩ and R3 = 2 MΩ
if the feedback resistance is considered to be 2 MΩ?
Q-6: a) What is the basic principle of a Schmitt trigger? Explain its working with the help of op-amp
circuits.
b) Describe low pass, high pass, band pass and band reject filters.
Q-7: What is the criterion for oscillations? What is positive feedback in amplifiers? Discuss Wien
Bridge Oscillator using OP-AMP with circuit diagram.
Q-8: Explain the construction and working of an SCR with necessary equivalent circuits and also
explains the terms breakdown voltage, holding current and forward current rating.
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