EC6202-Electronic Devices and Circuits Semester/EC6202-Electronic... · EC 6202 Electronic Devices...

EC 6202 Electronic Devices And Circuits (2017-18) Odd semester.

VALLIAMMAI ENGINEERING COLLEGE

SRM Nagar, Kattankulathur – 603 203

DEPARTMENT OF

ELECTRICAL AND ELECTRONICS ENGINEERING

QUESTION BANK

III SEMESTER

EC6202 - Electronic Devices and Circuits

Regulation – 2013

Academic Year 2017 – 18

Prepared by

Mr. K. Sanjay, Assistant Professor(OG)/ECE

Ms. S. R. Preethi, Assistant Professor(OG)/ECE


VALLIAMMAI ENGINEERING COLLEGE SRM Nagar, Kattankulathur – 603 203.

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

QUESTION BANK

SUBJECT : EC6202 Electronic Devices and Circuits SEM / YEAR: III / II

EC 6202 ELECTRONIC DEVICES AND CIRCUITS

UNIT-I: PN JUNCTION DEVICES

PN junction diode –structure, operation and V-I characteristics, diffusion and transient capacitance -Rectifiers

– Half Wave and Full Wave Rectifier,– Display devices- LED, Laser diodes- Zener diode characteristics-

Zener Reverse characteristics – Zener as regulator

PART A

Q.NO QUESTIONS BT

LEVEL DOMAIN

1. Explain model diffusion capacitance in PN junction diode. BTL 3 Applying

2. What is a rectifier? Name it’s types? BTL 1 Remembering

3. How to represent the symbol of the following

PN diode, Zener diode, LED, UJT.

BTL 1 Remembering

4. Find the diffusion capacitance for a silicon diode with a 15 mA forward

current, if the charge carrier transit time is 70ns.

BTL 3 Applying

5. With suitable expression what is transition capacitance and Diffusion

capacitance?

BTL 3 Applying

6. What is laser diode and give its applications? BTL 1 Remembering

7. Give the diode current equation. BTL 1 Remembering

8. List out the factors on which barrier potential depends. BTL 4 Analyzing

9. Compose the effect of temperature on reverse saturation current of a diode. BTL 5 Evaluating

10. Outline transformer utilization factor and state its value for HWR and FWR. BTL 2 Understanding

11. Compare and contrast between p-n junction diode and zener diode. BTL 4 Analyzing


12. Explain the terms knee voltage and breakdown voltage. BTL 5 Evaluating

13. Describe peak inverse voltage. BTL 2 Understanding

14. Interpret the term diffusion capacitance or storage capacitance. BTL 2 Understanding

15. Locate some of the applications of laser diode. BTL 2 Understanding

16. A silicon diode has a saturation current of 7.5 μA at room temperature to 300

°K. Estimate the saturation current at 400 ° K.

BTL 6 Creating

17. Distinguish between Zener Breakdown and Avalanche breakdown. BTL 4 Analyzing

18. What is meant by dynamic resistance of diode? BTL 1 Remembering

19. A Ge diode has a saturation current of 10μA at 300ᵒ K. Estimate the saturation

current at 400ᵒK.

BTL 5 Evaluating

20. Show the VI characteristics of Zener diode. BTL 1 Remembering

PART –B

1. i) Assess the action of a full wave rectifier using diodes and give waveforms of

input and output voltages. (6)

ii) A FW diode rectifier has V1=100sinωt , RL=900Ω and Rf=100Ω. Come up

with the peak and dc load current, DC load voltage, the peak instantaneous diode

current, the PIV on the diode, AC input power, output power, Rectification

efficiency of the FW rectifier. (7)

BTL 6

creating

2. Briefly enumerate the following

(i) Laser diodes (7)

(ii) Zener diode as a voltage regulator (6)

BTL1

Remembering

3. With neat sketch compose the construction, operation and its characteristics of

PN junction diode. Also list its advantages, disadvantages and its applications.

(13)

BTL3 Applying

4. (i) Determine the minimum and maximum values of the load resistance of the

zener shut regulator to meet the following specifications VS=24V, VZ=10V,

iZMIN=3mA, IZMAX=50mA and RL=250Ω. (7)

(ii) Show the circuit diagram of a half wave rectifier for producing a positive

output voltage. Explain the circuit operation and sketch the waveforms. (6)

BTL 1

Remembering

5

Make use of a diagram recollect the working of Zener diode and its forward and

reverse characteristics. Also distinguish between Avalanche and Zener break

downs (13)

BTL2

Understanding


6

Draw the circuit diagram and compose the working of full wave bridge rectifier

with output filter and derive the expression of average output current and ripple

factor (13)

BTL5

Evaluating

7

(i) Summarize the effect of temperature on PN junction diode and draw its

switching characteristics (8)

(ii) The reverse saturation of a silicon PN junction diode is 10μA. Infer the diode

current for the forward bias voltage of 0.6V at 25ᵒ (5)

BTL 2 Understanding

8 (i) Explain the construction, operation and characteristics of LED.(7)

(ii) Describe the zener diode shunt voltage regulator. (6)

BTL 1 Remembering

9 Derive ripple factor, PIV, efficiency and TUF of Bridge rectifier with circuit

diagram and input/output waveforms (13)

BTL4 Analyzing

10 Explain the operation of half wave rectifier and derive FF, PF, RF, TUF,

PIV and efficiency. (13)

BTL4 Analyzing

11 (i) Review the expression for current throught the PN junction diode (7)

(ii) Outline the following characteristics of zener diode (6)

1. Avalance breakdown

2. Zener breakdown

BTL 2

Understanding

12 (i) Explain the VI characteristics of zener diode.(6)

(ii) Brief about the terms Diffusion capacitance and transient capacitance with

respect to the diode (7)

BTL 1

Remembering

13 (i) In what aspect is a LED different from a PN junction diode? State the

applications of LED. (7)

(ii)Explain the working of center tapped full wave rectifier with and without filter

with neat diagrams. (6)

BTL 4

Analyzing

14 A bridge rectifier is supplied with 230V, 50Hz supply with stepdown ratio of 3:1

to a resistive load of 10kΩ. If the diode forward resistance is 75Ω while the

transformer secondary resistance is 10Ω. Calculate the maximum and average

values of current, dc output voltage and rms voltage, efficiency, ripple factor,

peak factor, form factor, PIV and TUF. (13)

BTL 3

Applying

PART –C

1. An AC supply of 220V, 50 Hz is applied to a HWR through a transformer of turn

ratio 10:1. Find (i) Maximum RMS load Voltage (ii) Maximum RMS load current

(iii) Power delivered to the load (iv) AC power input (v) Efficiency and ripple

factor (vi) PIV, ripple frequency, ripple voltage and ripple current (15)

BTL 3

Applying

2. A 230 V, 50 Hz voltage is applied to the primary of a 5:1 stepdown center-tapped

transformer used in a FWR having a load of 900Ω. If the diode resistance and the

secondary coil resistance together has a resistance of 100Ω determine, (i) DC


voltage across the load (ii) DC current flowing through the load (iii) DC power

delivered to the load (iv) PIV across each diode (v) Ripple voltage and its

frequency (15)

BTL 3 Applying

3 A germanium diode has a contact potential of .2volt while the concentration of

accepted impurity atoms is 3x10^20/m^3. Calculate for a reverse bias of .1 volt,

the width of the depletion region. If the reverse bias is increased to 10volt,

calculate the new width of the depletion region. Assuming cross sectional area of

the junction as 1mm^2 , Analyse the transition capacitance values for both the

cases. Assume Ɛr=16 for germanium (15)

BTL 5

Evaluating

4 (ii)Estimate the ideal reverse saturation current density in a silicon PN junction

at T=300K, Consider the following parameters in the silicon pn junction. Nd

=Na= 10^16cm^-3, ni= 1.5×10^10 cm^-3, Dn =25 cm2/s, Tp0= Tn0=5×10^-7 s,

Dp=10cm2/s, Ɛr =11.7 .Comment on the result. (15)

BTL 6

Creating

UNIT II- TRANSISTORS

BJT, JFET, MOSFET- structure, operation, characteristics and Biasing UJT, Thyristor and IGBT -

Structure and characteristics. PART A

Q.No Questions BT

Level

Domain

1. List any two points of comparison between JFET with BJT. BTL 1 Remembering

2. Distinguish between h-parameter and hybrid π model. BTL 2 Understanding

3. Solve Icand IE for a transistor that has αdc = 0.99and IB= 150μA. Determine the

value of β dc for the transistor.

BTL 3 Applying

4. Show how an SCR can be triggered on by the application of a pulse to gate

terminal.

BTL 2 Understanding

5. Inspect why it is necessary to stabilize the operating point of transistor. BTL 4 Analyzing

6. Compare BJT and FET. BTL 2 Understanding

7. Make use of the values of transistor has β=150, find the collector and base

current if IE= 10mA.

BTL 3 Applying

8. Identify some applications of JFET. BTL 3 Applying

9. How does a transistor act as a switch? BTL 1 Remembering

10. Examine “thermal runaway” in transistors. BTL 4 Analyzing

11. Why FET is more temperature stable compared to BJT? BTL 1 Remembering

12. Formulate the relation between αdc and βdc. BTL 6 Creating


13. What is meant by biasing a transistor? BTL 1 Remembering

14. Draw the two transistor equivalent of SCR. BTL 1 Remembering

15. Discuss the advantages of FET over BJT. BTL 6 Creating

16. Define amplification factor of JFET. BTL 1 Remembering

17. Explain the intrinsic standoff ratio of a UJT. BTL 2 Understanding

18. Distinguish the latching current & holding current. BTL 4 Analyzing

19. A BJT has a base current of 200μA. Determine the collector current and β. BTL 5 Evaluating

20. In a n channel JFET IDSS=20 mA and VP= -6V. Estimate the drain current when

VGS= -3V.

BTL 5 Evaluating

PART –B

1. With the help of suitable diagram, explain the working of enhancement MOSFET

(13)

BTL 1 Remembering

2. Describe the construction and working of UJT with it’s equivalent circuit and VI

characteristics. (13)

BTL1 Remembering

3. Elaborate the construction and operation of NPN transistor with neat sketch. Also

comment on the characteristics of NPN transistor (13)

BTL 6 Creating

4. With neat sketch, illustrate the construction, operation and characteristics of

SCR. (13)

BTL1 Remembering

5. Enumerate the selection of Q point for transistor bias circuit and discuss the

limitations on the output voltage swing (7)

Show the cross section diagram of an N type enhancement mode MOSFET.

Briefly explain its operation (6)

BTL 5 Evaluating

6. Demonstrate the basic construction and equivalent circuit of a UJT. Briefly

explain the device operation (7)

Show the four layer construction of SCR and two transistor equivalent circuit .

Explain the device operation (6)

BTL 1 Remembering

7. Model the CE configuration of NPN transistor, and explain its input and output

characteristics with suitable diagrams. (13)

BTL 3 Applying

8. Elaborately discuss the drain current characteristics and transfer characteristics

of MOSFET. (13)

BTL 2 Understanding

9. Recall the input and output characteristics of a CE transistor configuration. List

out the comparisons between CE, CB and CC configurations. (13)

BTL 2 Understanding

10. (i) Illustrate early effect describe with relevant expressions and figure (6)

(ii) Demonstrate the input and output characteristics of CE configuration (7)

BTL 3 Applying


11. Explain the structure and operation of Insulated Gate Bipoar Transistor.

(7)

Distinguish MOSFET and IGBT (6)

BTL4 Analyzing

12. (i) Examine the various current components in a transistor. (7)

(ii) Explain the performance of FET as a voltage regulator. (6)

BTL4 Analyzing

13. (i) Take part in discussion of the two transistor model of a thyristor in detail. (7)

(ii) Sketch and explain the typical shape of drain characteristics of JFET for

VGS=0 with indication of four region clearly. (6)

BTL4 Analyzing

14. (i) Elaborately discuss the structure and characteristics of IGBT. (7)

(ii) Summarize the operation of UJT. (6)

BTL 2 Understanding

PART –C

1. Design a voltage divider bias circuit for transistor to establish the quiscent point

at VCE=12V, IC=1.5mA, stability factor S≤3, β = 50, VBE=0.7V, VCC=22.5V and

RC=5.6kΩ. (15)

BTL 6 Creating

2. Draw d.c load line and a.c load line for the following transistor configuration.

Obtain the operating point. (15)

BTL 3

Applying

3. (i) For an n-channel silicon FET with a=3x10-4 cm and Nd=1015 electrons/cm-3.

Evaluate (a) pinch off voltage (b) the channel half width for VGS= 0.5Vp. (5)

(ii) In biasing with feedback resistor method, a silicon transistor with feedback

resistor is used. The operating point is 7V, 1mA and VCC=12V. Assume β=100.

Determine the value of RB, Stability factor and the new operation point if β=50

and all other circuit values the same. (10)

BTL 4

Analyzing

4. The reverse leakage current of the transistor when connected in CB configuration

is 0.2 mA and it is 18 μA when the same transistor is connected in CE

configuration. Determine αdc &βdc of the transistor. Assume IB =30mA.

(15)

BTL 5

Evaluating


UNIT-III: AMPLIFIERS

BJT small signal model – Analysis of CE, CB, CC amplifiers- Gain and frequency response –

MOSFET small signal model– Analysis of CS and Source follower – Gain and frequency response-High

frequency analysis

PART A

Q.No Questions BT

Level

Domain

1. Show the hybrid model of BJT in CE configuration BTL 1 Remembering

2. What are amplifiers? Write it’s uses? BTL 1 Remembering

3. Model the small signal equivalent circuit of a CS JFET. BTL 3 Applying

4. Justify the need of coupling capacitors in amplifier design. BTL5 Evaluating

5. Explain the four h-parameters. BTL 4 Analyzing

6. For an amplifier, midband gain =100 and lower cut-off frequency is 1 kHz.

Estimate the gain of an amplifier at frequency of 20Hz.

BTL 6 Creating

7. Explain the significance of coupling and bypass capacitor on BW of amplifiers. BTL 2 Understanding

8. Explain the term bandwidth and gain bandwidth product. BTL5 Evaluating

9. How can a DC equivalent circuit of an amplifier be obtained? BTL 1 Remembering

10. A common emitter amplifier has an input resistance of 2.5kΩ and voltage gain

of 200. If the input signal voltage is 5mV. Find the base current of the

amplifier.

BTL 1 Remembering

11. Point out why CE configuration is preferred over CB configuration. BTL 4 Analyzing

12. Outline the procedure to draw the a.c. equivalent of a network. BTL 2 Understanding

13. Identify the reason for fall in gain at low and high frequencies. BTL 3 Applying

14. Define an intrinsic standoff ratio of UJT and draw its equivalent circuit. BTL 1 Remembering

15. Discuss about thermal runaway and how it could be avoided. BTL 6 Creating

16. Develop the expression for pinch off voltage with respect to JFET. BTL 3 Applying

17. When VGS of the FEET changes from -3.1V to 3V the drain voltage changes

from 1 mA to 1.3mA Calculate the value of transconductance.

BTL 4 Analyzing

18. Define desensitivity. BTL 1 Remembering

19. Show the frequency response curve of an amplifier and what is 3 dB frequency. BTL 2 Understanding


20. Compare the performance of CE,CB,CC amplifier configurations. BTL 2 Understanding

PART –B

1. Illustrate the h-parameter model of a BJT-CE amplifier and derive the equations

for voltage gain, current gain, input impedance and output impedance (13)

BTL 2 Understanding

2. Describe about small signal MOSFET amplifiers (NMOS) and obtain the

expression for it transconductance. (13)

BTL1 Remembering

3. Develop the h parameter equivalent circuit for a typical common emitter amplifier

and derive the expression for Ai, Ri, Av and Ro. (13) BTL1 Remembering

4. Derive the expression for the voltage gain of CS amplifier (6)

For CS amplifier, the operating point is defined by VGSQ=-2.5V,Vp= -6V and

IdQ=2.5mA with IDSS=8mA. Also RG=1MΩ, RS=1 KΩ, RD=2.2KΩ and

VDD=15V.Calculate gm, rd, Zi, Zo and Av (7)

BTL3

Applying

5. Discuss the factors involved in Ic, Rc and Re for a single stage common

emitter BJT amplifier circuit, using voltage divider bias (7)

A CC amplifier shown in below figure has VCC=15 V, RB=75kΩ and

RE=910Ω The β of the silicon transistor is 100 and the load resistor is

600Ω. Estimate rin and Av (6)

BTL6

Creating

6. The MOSFET shown in below figure has the following parameters.

VT=2V, β=0.5×10 -3, rD=75kΩ. It is biased at ID=1.93 mA. Determine the

impedance and voltage gain (7)

BTL 5

Evaluating


With neat circuit diagram, evaluate the ac analysis for common source

using equivalent circuit NMOSFET amplifier (6)

7. Explain about CS amplifier and derive the expression for gain, input impedance

and output impedance and also draw its small signal equivalent circuit (13)

BTL 2 Understanding

8. The hybrid parameters of a transistor used as an amplifier in the CE configuration

arehie = 800Ω, hfe = 46, hoe = 80 x 10-6 and hre = 5.4x 10-4. If RL = 5K and Rs

=500Ω. Find Ai, Ri , Av, Pi. (13)

BTL3 Applying

9. Inspect the high frequency response of FET and derive the expression for lower

cut off frequency and upper cut off frequency (13)

BTL4 Analyzing

10. Demonstrate the low frequency analysis of BJT and also determine the effect of

Cs, Cc & Cc on the low frequency response of BJT (13)

BTL 2 Understanding

11. Explain about CC amplifier and derive the expression for h parameters of the

same. Also derive the expression for gain, input impedance and output

impedance of CC amplifier. (13)

BTL4 Analyzing

12. (i) What are the factors affect the bias stability of a transistor? (6)

(ii) Define the stability factors with respect to the changes in ICO,VBE and β.

Why is the stability with respect to VCE not considered? (7)

BTL1 Remembering

13. (i) Show the low frequency h-equivalent model of a transistor amplifier operating

in CE mode and why is this circuit not valid for high frequencies (7)

(ii) Define the trans conductance of BJT in the CE mode. How it is related to h

parameters. (6)

BTL 4 Analyzing

14. Draw the circuit diagram of common drain MOSFET amplifier. Derive the

expression for its voltage gain, input resistance and output resistance. (13)

BTL1 Remembering

PART –C

1. Determine the mid band gain, upper cutoff frequency of a common-source

amplifier fed with the signal having internal resistance Rsig=100kΩ. The

amplifier has RG=4.7MΩ, RD=RL=15kΩ, gm=1mA/V, ro=150kΩ, Cgs=1 pF and

Cgd=0.4pF. (8)


(ii) For CS amplifier, the operating point is defined by VGSQ=-2.5V, VP=-6V and

IdQ=2.5mA with IDSS=8mA. Also RG=1MΩ, RS=1KΩ,RD=2.2kΩ and VDD=15V.

Calculate gm, rd, Zi, ZO and AV. (7)

BTL 3 Applying

2. Examine the midband gain and bandwidth of a CE amplifier. Assume lower

cutoff frequency is 100Hz. Let Hfe=β=100, Cbe=4pF, Cbc=0.2pF and VA=∞.

(15).

BTL 4 Analyzing

3 The figure shows a common-emitter amplifier. Determine the input resistance,

ac load resistance, voltage gain and ouput voltage. (15)

BTL 3

Applying


4 For a CB amplifier driven by voltage source of internal resistance Rs=1200Ω.

The load impedance is resistor RL=1000Ω. The H parameters are Hin=22Ω,

Hcb=3x10-4, Hfb= -0.98 and Hinf=0.5A/V. Estimate the current gain A, Input

impedance Ri, voltage gain Av, overall gain Ais, overall voltage gain Avs and

output impedance Zo. (15)

BTL 5

Evaluating

UNIT-IV: MULTISTAGE AMPLIFIERS AND DIFFERENTIAL AMPLIFIER

BIMOS cascade amplifier, Differential amplifier – Common mode and Difference mode analysis – FET input

stages – Single tuned amplifiers – Gain and frequency response – Neutralization methods, power amplifiers

–Types (Qualitative analysis).

PART A

Q.No Questions BT

Level

Domain

1. What are cascaded amplifiers? BTL 1 Remembering

2. Model the ideal tuned circuits and write the expression for it’s resonant

frequency.

BTL 3 Applying

3. Explain how the differential amplifier can be used as an emitter coupled phase

inverter

BTL 4 Analyzing

4. Elaborate the need for neutralization. BTL 6 Creating

5. Identify the need for cascading the amplifiers. BTL 3 Applying

6. What is CMRR? Examine various methods of improving CMRR. BTL 4 Analyzing

7. Recall the applications of differential amplifier. BTL 1 Remembering

8. Why neutralization is important? And give its types. BTL 1 Remembering


9. Construct a Differential amplifier and what is the ideal value of CMRR? BTL 3 Applying

10. Distinguish common mode and difference mode. BTL 4 Analyzing

11. Summarize the Advantages and performance of class-c amplifier. BTL 2 Understanding

12. Explain the term cross over distortion. BTL 4 Analyzing

13. Illustrate the ideal tuned circuit and write the expression for it’s resonant

frequency. BTL 2 Understanding

14. State Miller’s theorem. BTL1 Remembering

15. Explain the bootstrapping technique. BTL5 Evaluating

16. Compare the performance of various power amplifier types. BTL 2 Understanding

17. Discuss need of Complementary symmetry amplifiers. BTL 6 Creating

18. Tell the advantages of Push pull amplifier. BTL1 Remembering

19. Enumerate the advantages of single tuned amplifiers. BTL1 Remembering

20. Outline the need for constant current source for difference amplifier. BTL 2 Understanding

PART B

1. Illustrate the circuit of emitter coupled BJT differential amplifier, and derive

expressions for differential gain, common mode gain and CMRR (13)

BTL 2 Understanding

2 What is Neutralization? Explain any one method in brief? (13) BTL 1 Remembering

3. With neat sketch explain two stage cascaded amplifier and derive its overall Av,

AI,RI and Ro (13)

BTL 3 Applying

4. Show the differential amplifier and its ac equivalent circuit. Derive for Ad and

Ac. (13)

BTL 1 Remembering

5. With neat sketch, explain the BJT differential amplifier with active load and

derive Ad, Ac and CMRR. How CMRR can be improved (13)

BTL 1 Remembering

6. Explain the different types of neutralization technique used in tuning amplifier

(13)

BTL 2 Understanding

7. Develop the equation for differential mode gain and common mode gain of a

differential amplifier. (13)

BTL 3 Applying

8. Interpret the qualitative analysis for power amplifiers. (13) BTL 5 Evaluating

9. Discuss the complementary symmetry class B amplifier and obtain its

efficiency (7)

Elaborate the operation of class AB amplifier to avoid cross over distortion

(6)

BTL 6 Creating

10. The dual input balanced output differential amplifier having Rs=100Ω, RC

=4.7KΩ, RE =6.8KΩ,hfe=100,VCC=+15V, VEE=-15V. Find operating point

BTL 1 Remembering


values, differential &common mode gain, CMRR and output if Vs1=70mV(p-p)at

1 kHz and Vs2=40mV(p-p) (13)

11. A Class C amplifier with VCC=25V has RL=680Ω,Cp=4300pF,Lp=20μH and

Rw=0.06Ω.The transistor has VCE(sat)=0.6V.Calculate the appropriate signal

frequency, the output power and circuit efficiency (13)

BTL 4 Analyzing

12. Draw a circuit diagram to show how the current in the output transistors of a

power amplifier can be limited to a desired maximum level. Examine the circuit

operation. (7)

Compare MOSFET to power BJT (6)

BTL 4 Analyzing

13. Classify the power amplifiers and calculate the efficiency each types (13) BTL 2 Understanding

14. Explain about Class A transformer coupled amplifier and derive the expression

for efficiency of the same. (13)

BTL 4 Analyzing

PART-C

1 Compare and differentiate the types of neutralization methods (15) BTL4 Analyzing

2 Solve the gain and frequency response of single tuned amplifiers. (15) BTL 6 Creating

3 The differential amplifier has the following values RC = 50 K, Re = 100K and

Rs = 10K. The transistor parameters are rπ = 50K= hie, hfe = Vo = 2 x10^3, ro =

400K.Determine Ad, Ac and CMRR in db. (15)

BTL 5 Evaluating

4 Construct BiMOS cascade amplifier. (15) BTL 3 Applying

UNIT-V: FEEDBACK AMPLIFIERS AND OSCILLATORS

Advantages of negative feedback – voltage / current, series, Shunt feedback –positive feedback –Condition

for oscillations, phase shift – Wien bridge, Hartley, Colpitts and Crystal oscillators.

PART A

Q.No Questions BT

Level

Competence

1. Tell the disadvantages of negative feedback in amplifiers and how it can be

overcome.

BTL 1 Remembering

2. Show the expression for the frequency of oscillations of a wein bridge

oscillator.

BTL 2 Understanding

3. Summarize the advantages of negative feedback circuits. BTL 2 Understanding

4. What is the advantage of a Colpitts oscillator compared to a phase shift

oscillator?

BTL 1 Remembering

5. Which is the most commonly used feedback arrangement in cascaded amplifier

and why?

BTL 1 Remembering

6. Recall the Barkhausan criterion for an oscillator. BTL 1 Remembering

7. Identify the difference between an oscillator and amplifier. BTL 3 Applying


8. Name two high frequency oscillators. BTL 1 Remembering

9. Outline the advantages of crystal oscillator. BTL 2 Understanding

10. Discuss about Nyquest’s stability criteria for feedback amplifiers. BTL 6 Creating

11. Develop the oscillator model uses both positive and negative feedback? Why? BTL 3 Applying

12. Determine the operating frequency of transistor Hartley oscillator if L1=50μH,

L2=1mH, and mutual inductance between the coils M=10 μH and C=10pF.

BTL5 Evaluating

13. List the five characteristics of an amplifier which are modified by negative

feedback.

BTL4 Analyzing

14. Elaborate on Piezo electric effect. BTL 6 Creating

15. List out the advantages of crystal oscillator. BTL 1 Remembering

16. Examine the effects on bandwidth and output impedance due to various types

of feedback.

BTL4 Analyzing

17. Illustrate the expression for frequency of oscillation of a Wein bridge oscillator. BTL 2 Understanding

18. Distinguish the negative and positive feedback. BTL4 Analyzing

19. Identify the limitations of LC and RC oscillators. BTL3 Applying

20. A wein bridge oscillator is used for operate at fo=10KHz. If the value of R is

100Ω. Estimate the value of capacitor.

BTL 5 Evaluating

PART-B

1. Illustrate the circuit of CE amplifier with current series feedback and obtain the

expression for feedback ratio, voltage gain, input and output resistances. (13)

BTL 2 Remembering

2 Explain the operation of Colpitts Oscillator with neat circuit diagram. Also

derive the expressions for the frequency of oscillation and the condition for

maintenance of oscillation. (13)

BTL 2 Remembering

3. Calculate Rif, Rof, Av and Avf for the following

(i) Voltage hunt feedback amplifier (7)

(ii) Current series feedback amplifier (6)

BTL 4 Analyzing

4. Outline the following with neat diagram.

(i) RC phase shift oscillator.(7)

(ii) Hartley oscillator. (6)

BTL 2

Understanding

5 Make use of a circuit diagram explain the operation of the following

oscillators.

(i) Wein bridge oscillator (4)

(ii) Design a Wein bridge oscillator circuit to oscillate at a

frequency of 20kHZ. (4)

(iii) Crystal oscillator. (5)

BTL 3 Understanding


6 Sketch a circuit diagram of a two stage capacitor coupled BJT amplifier that uses

series voltage negative feedback. Describe how the feedback operates.

(13)

BTL 1 Remembering

7 Show the circuit diagram explain the operation of an RC phase shift oscillator

and derive the condition for oscillation and resonant frequency with BJT. (13)

BTL 1 Remembering

8 Take part in the discussion of the four types of topology for feedback of an

amplifier. Derive the expression for gain with feedback. Mention the advantages

of negative feedback amplifier. (13)

BTL 4 Analyzing

9 Solve the frequeny of expression for any two types of oscillator (13) BTL6 Creating

10 A Hartley oscillator is designed with L1 = 2mH, L2 = 20μH and a variable

capacitance. Find the range of capacitance value if the frequency of

oscillation is varied between 950 to 2050 KHZ (13)

BTL 1

Remembering

11 Explain the general characteristics of a negative feedback amplifier.

Represent voltage series, voltage shunt, current series and current shunt.

(13)

BTL 4

Analyzing

12 What is the condition for oscillation of a Hartley Oscillator. Briefly explain

the operation and derive the equation for fr and hfe. (13)

BTL 1 Remembering

13 Compare and differentiate the types of oscillators (13)

BTL 5

Evaluating

14 With a neat circuit diagram, describe the working of a Wien bridge

oscillator. Derive an expression for the resonant frequency. Give its

advantages and disadvantages (13)

BTL 3

Understanding

PART-C

1 Two identical amplifier stages , each with voltage gain of 20dB and B.W

of 25kHz are cascaded. To improve gain stability the cascade is provided

with negative feedback to the extent of 10%. Estimate the effective gain

and bandwidth. (15)

BTL4 Analyzing

2 Interpret the various feedback arrangements (15) BTL 5 Evaluating

3 Construct phase shift oscillators (15) BTL 3 Applying

4 Design a Colpitts oscillator with C1 = 100pf and C2 = 7500pf. The inductance is

variable. Determine the range of inductance values, if the frequency of oscillation

is to vary between 950 KHz and 2050 KHz. (15)

BTL 6 Creating

Date post:	19-Mar-2018
Category:	Documents
Upload:	ngodiep
View:	260 times
Download:	12 times

EC6202-Electronic Devices and Circuits Semester/EC6202-Electronic... · EC 6202 Electronic Devices...

Documents