EC6304 Electronic Circuits-I, Second year, Department of Electronics & Communication Engineering, First and second Units Questions

Answer All Questions
PART- A (10 x 2 = 10 Marks)
1.      Why biasing is necessary   in BJT Amplifier?
2.      Define Stability factor.
3.      List out the various biasing circuits for BJT.
4.      What is loading effect?  And how to minimize it?
5.      Draw the simplified small signal hybrid  equivalent circuit for npn transistor.
6.      What is transconductance?
7.      What is thermal run away?
8.      Draw and explain the concept of DC Load line.
9.      What is voltage swing limitation?
10.  Why are CE amplifiers more popular?

PART-B (5X13=65Marks)

11.  a)  Determine the bias resistor  RB for fixed bias and collector to base bias circuit and compare the stability factor ‘S’ for both of them. Given Vcc=12V, RL=330Ω, IB=0.3mA,β=100,VCEQ=6v.
(OR)
      b) Explain in detail about Emitter Stabilized Bias circuit.        
1.      a) Explain in detail about various bias compensation techniques in BJT.                                           
(OR)
            b) Explain the concept of fixed bias circuit for BJT and derive its various stability factors.               
2.      a) Explain in detail about voltage divider bias circuit for JFET with neat diagram and steps.  
(OR)
      b) Explain in detail the small signal analysis of Common Emitter Amplifier with bypassed RE and Unbypassed RE with neat sketch.                                                                                                          
14.             a) Derive the expression of Ri, Av and Ro for Common Collector amplifier.
(OR)
      b) Derive the expression of Ri, Av and Ro for Common Base amplifier.       
15. a) With neat sketch, explain in detail about Cascode amplifier.
(OR)
      b)i) Design a collector to base bias circuit for the specified conditions: VCC=15V, VCE=5V, IC=5mA and β=100
          ii) Design a collector to base bias circuit to have operating point of (10V,4mA). The circuit is supplied with 20V and uses a silicon transistor of hfe=250.                    
PART-C (1X15=15)
16.  With neat circuit diagram, explain in detail about the voltage divider bias circuit and derive the expression for the stability factor of voltage divider bias circuit.