# ANU B.Tech 1st Semester Electronic Circuits II April 2014 Question Paper

III/IV B.Tech Degree Examinations, April 2014
College: Bapatla Engineering College
QP University / Exam Board: Acharya Nagarjuna University
First Semester
Electronic Circuits II
Time : 3 hours
Maximum Marks : 60
Answer ONE question from each Unit

1. Briefly explain following [12 x 1 = 12M]
a) Given transistor Ic = 26 m A. Find the value of gm at room temperature.
b) What is the relation between fβ and fT?
c) What is the value of CE short circuit current gain at signal frequency f = fβ?
d) Write the formula for emitter diffusion capacitance Ce in terms of gm and fT.
e) Draw the small signal model of FET
f) What are the advantages of SMPS over conventional power supplies?
g) Compare series and shunt voltage regulators.
h) Write the formula for overall upper 3 dB frequency of n cascaded stages.
i) In low frequency region the amplifier acts as which filter?
j) Write the formula for bandwidth of parallel resonant circuit.
k) Mention the applications of Tuned amplifiers.
l) Draw the frequency response of double tuned amplifier.

UNIT - I [1 x 12 = 12M]

2. a) Draw the circuit of hybrid-π CE transistor model and define the components.
2. b) The following low-frequency parameters are known for a given transistor at Ic = 10 m A, Vce = 10 V at room temperature. hie = 500 ohms, hoe = 4x10-5 A/V, hfe = 100 and hre = 10-4 at the same operating point, fT = 50 M Hz and Cob = 3 pF. Compute the values of all the hybrid-π parameters. (OR)
3. a) Derive the expression for CE current gain with resistive load using equivalent circuit.
3. b) Given the germanium p-n-p transistor whose base width is 10-4 cm. At room temperature and for dc emitter current of 2 mA, find the emitter diffusion capacitance and fT.

UNIT - II [1 x 12 = 12M]

4. a) Draw the equivalent circuit of common source (CS) amplifier at high frequencies and Explain.
4. b) Derive the expressions for voltage gain, input admittance and input capacitance of CS amplifier at high frequencies. (OR)
5. a) Explain the operation of SMPS with neat block diagram.
5. b) Explain design of Shunt regulator with example.

UNIT - III [1 x 12 = 12M]

6. a) Derive the low frequency response and high-frequency response of RC-coupled amplifier with expressions and graph.
6. b) Explain distortions in amplifiers. (OR)
7. a) Derive the expressions for over all band pass of cascaded stages.
7. b) Three identical cascaded stages have individual upper 3 dB frequency of 100 kHz and lower 3 dB frequency of 100 Hz. What is overall fH and fL?

UNIT - IV [1 x 12 = 12M]

8. a) Draw the Parallel-Resonant circuit and explain with Impedance function and bandwidth.
8. b) Draw the circuit of single tuned amplifier and explain its operation with frequency response. (OR)
9. a) Draw the circuit of double tuned transformer coupled amplifier and explain its operation with frequency response.
9. b) Draw the circuit of tuned secondary amplifier and explain its operation.