 MORE IN Electronic Devices & Circuits
SPPU Electronics and Telecom Engineering (Semester 3)
Electronic Devices & Circuits
May 2014
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Answer any one question from Q1 and Q2
1 (a) Explain what is meant by Thermal Runway in BJT circuits.
6 M
1 (b) The transistor in connected in CE amplifier with bypassed RE has R1=50 KΩ. R2=2 KΩ, RC=1 KΩ, RS=1 KΩ, RL=10 KΩ. Also h-parameters are hie = 1.1 KΩ, hfe=50, hoe=24 μ A/V, hre=2.5K× 10-4. Determine the value for Av, AI, Ri.
6 M

2 (a) Determine the operating point and draw DC and AC Load Line if VCC=12 V, R1=8 KΩ, R2=4 KΩ, RE=1KΩ, RC=1 KΩ, RL=1.5 KΩ. Assume VBE=0.7 V.
6 M
2 (b) Compare CE, CB and CC amplifier performance parameters.
6 M

Answer any one question from Q3 and Q4
3 (a) Draw hybrid -π CE Amplifier model at high frequency. Explain significance of each parameter.
6 M
3 (b) An amplifier has gain of 60 and distortion is 10 % without feedback. Determine: (i) Gain, (ii) Distortion, when negative feedback is applied. Assume feedback factor as 0.1
6 M

4 (a) Explain the effect of Emitter bypass capacitor on low frequency response of BJT amplifier.
6 M
4 (b) Explain RC Phase Shift Oscillator using BJT and determine the output frequency for R = 1 KΩ, C=0.01 μF.
6 M

Answer any one question from Q5 and Q6
5 (a) In a Class A amplifier VCE(max)=25 V, VCE(min)=5 V. Find the overall efficiency for: (i) series fed load, (ii) transformer load.
6 M
5 (b) With the help of neat circuit diagram, explain the operation of Class AB power amplifier. Explain the significance of Class AB.
7 M

6 (a) Draw and explain Transformer coupled Audio Power Amplifier. Derive the expression for its efficiency.
6 M
6 (b) A Class B push pull amplifier is supplied with VCC=50 V. The signal swings the collector voltage down to Vmin=10V. The total dissipation in both transistors is 40W. Find: i) Pin(dc), ii) Pα(x), iii) % η.
7 M

Answer any one question from Q7 and Q8
7 (a) Describe the internal capacitance and high frequency model of MOSFET.
6 M
7 (b) E-MOSFET biased in CS configuration has following parameters: R1=10MΩ, R2=6.8 MΩ, RD=2.2 K&OMega;, VDD=24 V, VT=3V, ID(ON)=5 mA, VGS(ON)=6 V. Determine the values for ID and VDS.
7 M

8 (a) Enlist biasing of EMOSFET in common source configuration and explain any one of them in detail.
6 M
8 (b) Explain various non-ideal current voltage characteristics of EMOSFET.
7 M

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