Anna University
Regulation 2008
Department of Electronics and Communication Engineering
3rd Semester
EC 2205 Electronic Circuits- I Question Bank 16 Mark Questions
Unit I
1. Explain the need for biasing , Stability factor and Fixed bias circuit (16)
2. Explain in detail different types of biasing circuits (16)
3. Explain the advantage of self bias (voltage divider bias) over other types of biasing. (16)
4. Explain the various types of bias compensation techniques. (16)
5. i) Explain biasing of FET (8)
ii) Explain biasing of MOSFET (8)
Unit II
1. Explain the AC and DC Analysis of Common Emitter amplifier. (16)
2. Explain the AC and DC Analysis Common Base Amplifier. (16)
3. Explain the AC and DC Analysis Common collector Amplifier. (16)
4. Draw the circuit of a common source FET amplifier & explain its operation (16)
5. Briefly explain the operation of a Darlington emitter follower and also derive an expression for its performance measures (16)
6. What is a differential amplifier? Explain its working in common mode operation. Obtain its
AC equivalent circuit & drive the expression for voltage gain (16)
7. Draw the circuit diagram of a differential amplifier. Explain the operation in difference mode and common mode (16)
8. What are the methods to improve the CMRR of differential amplifier? Detail any two of them. (16)
9. i) Explain with circuit diagram the boot strapped Darlington emitter follower. (8)
ii) Draw the circuit diagram of self-bias circuit using CE configuration and explain how it stabilizes operating point. (8)
10. Draw the small signal hybrid model of CE amplifier and derive the expression for its AI,AV,RI and RO.
Unit III
1. Derive the expression for the CE short circuit current gain of transistor at high frequency (16)
2. i)What is the effect of Cb’e on the input circuit of a BJT amplifier at High frequencies? (8)
ii) Derive the equation for gm which gives the relation between gm, Ic and temperature. (8)
3. i) Draw the high frequency hybrid –π model for a transistor in the CE configuration and explain the significance of each component. (12)
ii) Define alpha cut off frequency. (4)
4. i) Define fα,fβ and fT and state the relation between fβ and fT (8)
ii) Explain the significance of octaves and decades. (8)
5. Define unity gain frequency. Obtain the necessary relation using transistor frequency response. (16)
6. Using hybrid π model for CE amplifier. Derive an expression for its short circuit current gain.
Unit IV
1. Draw a neat circuit diagram of push-pull class-B amplifier. Explain its working. (16)
2. For the transformer – coupled class A power amplifier circuit derive the expression for its efficiency. (16)
3. Prove that the maximum efficiency of class B amplifier is 78.5% and that of Class A type is
50%. (16)
4. i) Compare class A, class B and class C power amplifier in their performance and efficiency. (10)
ii) Give the design procedure for heat sinks. (6)
5. What is the difference between a voltage amplifier and a power amplifier? (16)
6. Discuss the advantage and disadvantage of a complementary symmetry class B amplifier (16)
7. With the help of neat diagram. Explain the characteristics of class A amplifier and also derive
an expression for its efficiency and figure of merit.
Unit V
1. i. Explain the Concepts of Feedback in Amplifier. (8)
ii. Give the properties of Negative feedback. (8)
2. Discuss the differential voltage/current-series/shunt feedback connections with expression for gain, input resistance and output resistance. (16)
3. Draw and explain various feedback amplifier topologies (16)
4. Determine the voltage gain, input and output impedence with feedback for Voltage series feedback having A =-100, Ri=10kΩ, Ro=20 kΩ and β= -0.1 (16)
5. With the topologies compare the four types of negative feedback amplifier? (16)