JNTU QUESTION BANK ELECTRONIC CIRCUIT ANALYSIS MODEL QUESTION PAPER PREVIOUS YEAR QUESTION PAPER FOR 2ND YEAR FIRST SEMESTER ECE,CEET BRANCHES
JNTU QUESTION BANK ELECTRONIC CIRCUIT ANALYSIS MODEL QUESTION PAPER PREVIOUS YEAR QUESTION PAPER FOR 2ND YEAR FIRST SEMESTER ECE,CEET BRANCHES
II B.Tech I Semester Regular Examinations, November 2007
ELECTRONIC CIRCUIT ANALYSIS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) With the help of necessary equations, discuss the variation of AI ,AV ,Ri, andRo with RS and RL in Common Emitter configuration.
(b) For a CE configuration, what is the maximum value of RS for which Ro differs
by no more than 10 percent of its value for RS = 0. The h-parameter values
are hfe = 50, hie =1.1K
, hre = 2.5x10−4, hoe = 25 µA/V. [10+6]
2. A two-stage amplifier circuit (CE-CC configuration) is shown in figure 2. The h-
parameter values are hfe = 50, hie=2 K
, hre =6× 10−4, hoe = 25µA/V.
hfc = -51, hic =2 K
, hrc = 1, hoc = 25µ A/V.
Find the input and output impedances and individual, as well as overall voltage
and current gains.
Figure 2
3. (a) Draw Hybrid - π model for a transistor in the CE configuration and explain
the significance of every component in this model.
(b) Given a germanium p-n-p transistor whose basewidth is 10−4 cm. At room
temperature and for a dc emitter current of 2 mA, find
i. emitter diffusion capacitance,
ii. fT [Assume Diffusion constant as 47 cm2/sec]. [8+8]
4. (a) In series fed Class - A power amplifier, explain the importance of the position
of operating point on output signal swing. Show that the conversion efficiency
is 25%.
(b) Discuss the origin of various distortions in transistor amplifier circuits. [10+6]
5. Draw the circuit diagram of a Double tuned amplifier and derive the expression for
3-dB bandwidth. [16]
6. Explain the reasons for oscillations in a tuned amplifier. Briefly explain the methods
used to stabilize the tuned amplifiers against oscillations? [16]
7. (a) Explain why voltage regulators are called as closed loop control systems?
(b) A power Supply having output resistance of 2 ohms supplies a full-load current
of 100mA to a 50 ohms load. Find the percent voltage regulation and no-load
output voltage of the supply?
(c) Draw and explain the load voltage and load current characteristic for a current
limited regulator. [4+6+6]
8. (a) What is catcher diode and explain the necessity of catches diode in Switch
Regulator with the help of circuit diagram.
(b) List the operating ratings and electrical characteristics of IC 723. [8+8]
II B.Tech I Semester Regular Examinations, November 2007
ELECTRONIC CIRCUIT ANALYSIS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Draw the circuit diagram of CB- amplifier and its h-parameter equivalentcircuit. List out the characteristics of a CB amplifier.
(b) In a single stage CB amplifier circuit, RE = 20K,RC = 10K, VEE = −20V, VCC =
20V,RL = 10KandRS = 0.5K. Find AI ,Ri,Ro,AV . (8+8)
2. (a) How are multistage amplifiers classified depending upon the type of coupling.
(b) Write a note on distortions in amplifiers.
(c) If eight identical amplifiers are cascaded each having fH =200 KHz, determine
the overall upper 3dB frequency f
h. Assume non interacting stages. [5+6+5]
3. Derive all components in the Hybrid - π model in terms of h parameters in CE
configuration. [16]
4. (a) Classify large signal amplifiers based on their operating point. Distinguish
these amplifiers in terms of the conversion efficiency. [8]
(b) Draw the complimentary symmetry class-B power amplifier and explain its
operation. [8]
5. (a) Draw and explain the circuit diagram of a single tuned Capacitance coupled
amplifier. Also explain its operation?
(b) Draw and explain the significance of Gain versus Frequency curve of tuned
amplifiers when they are used in radio amplifiers?
(c) Draw the Ideal and actual frequency response curves of a single tuned ampli-
fier? [8+4+4]
6. (a) What is synchronous tuning ? Derive an expression for bandwidth of an n-
stage synchronously tuned amplifier?
(b) Show that for an ‘n’ stage synchronously tuned amplifier, maximum. band-
width is obtained when the single stage gain is 4.34dB. [8+8]
7. (a) Draw and explain a circuit which limits the current that can be drawn from
the supply to a certain specific maximum.
(b) Determine the minimum and maximum values for series resistor, required for
a zener diode regulator with an output voltage of 5.6V, if the supply voltage
varies from 10 V to 50V. The maximum load current is 20mA and minimum
zener current is 3 mA. [8+8]
1 of 2
Code No: R059210404 Set No. 2
8. (a) Specify suitable component values to get Vo=7.5V in the circuit of (Given
figure8a). Using a 7805 regulator. From data sheet. IQ=4.2mA and VR=5V,
choose IR1=25mA.
Figure 8a
(b) Draw the functional diagram SMPS and explain its operation.
II B.Tech I Semester Regular Examinations, November 2007
ELECTRONIC CIRCUIT ANALYSIS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Draw the circuit diagram and low frequency equivalent circuit of commonsource amplifier and derive an expression for its voltage gain.
(b) For the emitter follower circuit with RS = 0.5K and RL = 5K, calculate
AI ,Ri,AV ,AV S, and R0. Assume, hfe = 50, hie =1K, hoe = 25 µA/V. [8+8]
2. (a) Discuss about different types of distortions that occur in amplifier circuits
(b) Three identical non interacting amplifier stages in cascade have an overall
gain of 1 dB down at 30 Hz compared to mid band. Calculate the lower cutoff
frequency of the individual stages. [8+8]
3. (a) Draw Hybrid - π model for a transistor in the CE configuration and explain
the significance of every component in this model.
(b) Given a germanium p-n-p transistor whose basewidth is 10−4 cm. At room
temperature and for a dc emitter current of 2 mA, find
i. emitter diffusion capacitance,
ii. fT [Assume Diffusion constant as 47 cm2/sec]. [8+8]
4. (a) Classify large signal amplifiers based on its operating point. Distinguish these
amplifiers in terms of the conversion efficiency. [8]
(b) Draw the push-pull power amplifier circuit. Derive the expression for the
output current in push ?pull amplifier with base current as ib = Ibm sinwt. [8]
5. (a) Draw and explain the circuit diagram of a single tuned Capacitance coupled
amplifier. Also explain its operation?
(b) Draw and explain the significance of Gain versus Frequency curve of tuned
amplifiers when they are used in radio amplifiers?
(c) Draw the Ideal and actual frequency response curves of a single tuned ampli-
fier? [8+4+4]
6. Explain how the stagger-tuned design is superior over synchronously tuned design
in the design of a multistage amplifier? Also draw their circuit diagrams and their
equivalent circuits? [16]
7. (a) What is Voltage regulator? Explain with the help of neat circuit diagram how
zener diode is used as a shunt voltage regulator?
1 of 2
Code No: R059210404 Set No. 3
(b) In figure 7 shown Vi=20V, Rs=200 ohms and Vz=12V, VBE =0.65V find
output voltage, collector to emitter voltage of the transistor and the current
in 200 ohms resistor? [8+8]
Figure 7
8. (a) Draw and explain the output of pulse width modulator for different types of
inputs with respect to switching regulator.
(b) Draw the circuit and explain the operation of basic switching type regulator.
[8+8]
⋆ ⋆ ⋆ ⋆ ⋆
II B.Tech I Semester Regular Examinations, November 2007
ELECTRONIC CIRCUIT ANALYSIS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Draw the circuit diagram of CB- amplifier and its h-parameter equivalentcircuit. List out the characteristics of a CB amplifier.
(b) In a single stage CB amplifier circuit, RE = 20K,RC = 10K, VEE = −20V, VCC =
20V,RL = 10KandRS = 0.5K. Find AI ,Ri,Ro,AV . (8+8)
2. (a) How multistage amplifiers are classified depending upon the type of coupling.
(b) Write a note on distortions in amplifiers.
(c) In an R-C coupled amplifier, AVM = 60, fL = 50Hz and fH=100KHz. Find
the values of frequencies at which the gain reduces to 50 on either side of mid
band region. [4+6+6]
3. (a) What are the typical values of various components in Hybrid - π model? Show
that at low frequencies the Hybrid - Ï€ model with rb′e and rce taken as infinite
reduces to the approximate CE h- parameter model.
(b) The following low- frequency parameters are known for a given transistor at
IC = 10mA, VCE =10 V, and at room temperature,
hie = 500
hoe = 4x10−5 A/V
hfe = 100
hre = 10−4.
At the same operating point, fT = 50MHz and Cc=3PF, compute the values
of all the Hybrid - π parameters [8+8]
4. (a) Define thermal resistance of a power BJT.
(b) A transistor with a maximum junction temperature specification of 1500C
dissipates a maximum power of 40 watts at a case temperature of 250C and 2
watts at an ambient temperature of 250C. Find
i. The thermal resistance between the junction and the case.
ii. The thermal resistance between the junction and ambient.
iii. Maximum power dissipation capability for safe operation in free space at
a temperature of 500C. [4+4x3]
5. (a) What is meant by the term Tuned amplifier and briefly explain the various
methods of classification of tuned amplifiers?
1 of 2
Code No: R059210404 Set No. 4
(b) A constant generator drives a parallel tuned circuit consisting of a loss less
capacitor ‘C’ and a coil ‘L’ (having small resistance ‘R’). Derive the expression
for the frequency of resonance? [8+8]
6. (a) Explain the principle of a wideband amplifier?
(b) Derive the expression for Optimum value of collector circuit resistor (RC, opt)
of one stage of a CE cascade amplifier. Draw the graph showing the variation
of Bandwidth, Gain and Gain bandwidth product as a function of RC and
write the comments from the graph to improve the bandwidth. [4+12]
7. (a) With the help of a neat circuit diagram, explain the operation of BJT shunt
voltage regulator.
(b) What is a voltage reference? Why is it needed?
(c) What is the function of a series pass transistor? [8+4+4]
8. (a) Explain how three terminal IC 7805 is used as a current source with a neat
circuit diagram. [8]
(b) What is a Voltage multiplier? Draw and explain any one circuit of it and give
its applications. [8]
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