DHANALAKSHMI COLLEGE OF ENGINEERING DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING EC6202 ELECTRONIC DEVICES AND CIRCUITS UNIT-I - PN DIODEAND ITSAPPLICATIONS 1. What is depletion region in PN junction? 2. What are the other names of depletion region? 3. What is meant by barrier potential? 4. What is meant by biasing a PN junction? 5. What are the types of biasing a PN junction? 6. What is meant by forward bias and reverse bias in a PN junction? 7. What is meant by reverse bias in a PN junction? 8. What is meant by reverse saturation current? 9. Why do contact differences of potential exist in PN junction? 10. What is the static resistance of a diode? 11. Define Dynamic Resistance 12. What is meant by an amplifier? 13. Why do we choose q point at the center of the load line? 14. When does a transistor act as a switch? 15. What is meant by biasing? 1. Explain in detail, the drift current and diffusion current and derive equations for it. 2. Explain in detail, the construction and working of PN diode with a neat sketch. 3. Explain in detail, the construction and working of Zener diode with a neat sketch. 4. Explain the working of center tapped full wave rectifier(with and without filter) with neat diagrams and derive the necessary equations. 5. Explain in detail, the Zener shunt regulator. 6. Explain the effect of temperature of a diode. 7. Explain the construction and working of LED with its characteristics. 8. Draw the circuit diagram of half wave rectifier and explain its operation with necessary waveform. Also derive the expression for rectification efficiency and TUF. 9. Explain the principle and operation of Laser diode with neat diagram. 10. 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, calculate the transition capacitance values for both the cases. Assume r =16 for germanium.
UNIT II 2. Define Transistor 3. Write the current amplification factor for a CB transistor. 4. Write the formula for input resistance in a CB transistor 5. Write the current amplification factor for a CE transistor. 6. What is meant by transistor action? 7. Define Delay Time 8. Define Rise Time 9. Define Turn-on Time 10. Define Fall Time 11. Define Storage Time 12. Define Turn-off Time 13. Define Hybrid parameters. 14. What is the use of h-parameters? 15. Define Power Transistors 16. Which is the most commonly used transistor configuration? Why? 1. Explain the input and output characteristics of a CE transistor configuration. List out the comparisons between CE, CB and CC configurations. 2. Describe the static input and output characteristics of a CB transistor with neat circuit diagram. 3. Draw and explain the characteristics of CC configuration. 4. With a neat sketch explain the construction and characteristics of enhancement MOSFET. 5. With a neat sketch explain the construction and characteristics of DEMOSFET. 6. Explain the construction of N channel JFET and also explain the drain and transfer characteristics of the same. 7. Explain the construction and characteristics of UJT with a neat sketch. 8. Explain the working of UJT as relaxation oscillator in detail. 9. With a neat sketch explain the construction and working characteristics of a SCR. 10. With a neat sketch explain the construction and working characteristics of IGBT.
UNIT - III - FET AND ITS APPLICATIONS 1. What are the advantages of FET? 2. Define Latching Current 3. Define Holding Current 4. Define Turn-off Time 5. What are the advantage of SCR? 6. Write some applications of thyristor. 7. Define Finger Voltage 8. What is the name for solid state equivalent of thyristor? 9. Define Inter-base Resistance 10. Define Pinch-off Voltage 1. The hybrid parameters of a transistor used as an amplifier in the CE configuration are h ie = 800, h fe = 46, h oe = 80 x 10-6 and h re = 5.4x 10-4. If R L = 5K and R s = 500.Calculate Ai, Ri, Av,Pi. 2. Explain CE amplifier and derive the expression for h parameters of the same. Also derive the expression for gain, input impedence and output impedence of CE amplifier. 3. Explain CB amplifier and derive the expression for h parameters of the same. Also derive the expression for gain, input impedence and output impedence of CB amplifier. 4. Explain CC amplifier and derive the expression for h parameters of the same. Also derive the expression for gain, input impedence and output impedence of CC amplifier. 5. Explain CS amplifier and derive the expression for gain, input impedance and output impedance and also draw its small signal equivalent circuit. (May 2013) 6. Explain CD amplifier and derive the expression for gain, input impedence and output Impedence. 7. Explain the low frequency analysis of BJT and also determine the effect of Cs, Cc & Cc on the low frequency response of BJT. 8. Explain the high frequency response of FET and derive the expression for lower cut off frequency and upper cut off frequency. 9. The differential amplifier has the following values RC = 50 K, Re = 100K and Rs = 10K. Ad, Ac and CMRR in db.
UNIT IV - AMPLIFIERS AND OSCILLATORS 1. Define DC Load Line 2. What is the necessity of the coupling capacitor? 3. Why is the operating point selected at the centre of the active region? 4. Define Operational Amplifier 5. What happens when the common terminal of V+ and V- sources is not grounded? 6. Define Input Offset Voltage 7. Define Input Offset Current 8. Define CMRR of an op-amp 9. In practical op-amps, what is the effect of high frequency on its performance? 10. Define Slew rate 11. Write any two audio frequency oscillators. 12. Write some of the linear applications of op amps. 13. Write some of the non linear applications of op-amps. 14. What are the areas of application of non-linear op- amp circuits? 1. Draw the circuit diagram of an emitter coupled BJT differential amplifier and derive expressions for differential gain, common mode gain, CMRR, input impedance and output impedance. 2. Explain the Class A transformer coupled amplifier and derive the expression for efficiency of the same. 3. Explain the Class B pushpull amplifier and derive the expression for efficiency of the same. 4. Explain with a neat sketch the working of single tuned voltage amplifier using FET. 5. Derive the frequency response of single tuned voltage amplifier and also give its limitations. 6. Explain the Class AB amplifier in detail. Give its advantages and disadvantages. 7. Explain Class C amplifier in detail. 8. Explain the Class A RC coupled amplifier and derive the expression for efficiency of the same. 9. With a neat sketch explain stagger tuned amplifier. 10. Explain the working of complimentary symmetry class B push pull amplifier. What are its merits and de-merits?
UNIT V PULSE CIRCUITS 1. What is meant by multivibrator? 2. What is meant by monostable multivibrator? 3. What is meant by astable multivibrator? 4. What is meant by bistable multivibrator? 5. What are the requirements for producing sustained oscillations in feedback circuits? 6. What is meant by filter? 7. What are the demerits of passive filters? 8. What are the advantages of active filters? 9. List out some commonly used active filters. 10. List out some applications of 555 timer: 11. List out the applications of 555 timers in monostable mode of operation: 12. List out the applications of 555 timers in Astable mode of operation: 13. What is meant by combinational logic? 14. Explain the design procedure for combinational circuits. 1. Draw and describe the four types of topology for feedback of an amplifier. Derive the expression for gain with feedback. Mention the advantages of negative feedback amplifier. 2. With a neat diagram explain about Colpitt oscillator & derive the expression for frequency of oscillation and condition of oscillation. 3. With a neat diagram explain about Hartley oscillator & derive the expression for frequency of oscillation and condition of oscillation. 4. Explain the operation of crystal oscillator with neat diagram and write the expression for its frequency of oscillation. 5. A colpitt oscillator is designed 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. 6. With a neat circuit diagram, describe the working of a Wien bridge oscillator. Derive an expression for the resonant frequency. 7. With neat circuit diagram explain the operation of an RC phase shift oscillator and derive the condition for oscillation and resonant frequency with BJT. 8. Voltage series negative feedback amplifier has a voltage gain without feedback of A=500, input resistances (R i )=3kΏ, output resistance R o =20kΏ, and feedback ratio of β= 0.01. Calculate the voltage gain A F, input resistance (R if ) and output resistance (R of ) of amplifier with feedback. 9. A Hartley oscillator is designed with L1 = 2mH, L2 = 20µH and a variable capacitance. Determine the range of capacitance value if the frequency of oscillation is varied between 950 to 2050 KHZ.