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# SRM University 2007 B.Tech Information Technology EC205 -- ELECTRONIC CIRCUITS - I - Question Paper

Wednesday, 30 January 2013 07:20Web
Unit – III
Part –A
1. Why models are necessary? Draw a hybrid model for a BJT.
2. Draw a small signal Low Frequency Model of JFET.
3. Define Cascode Amplifier?
4. Define CMRR of a differential amplifier.
5. For a CE Amplifier, provided Rc=2K hfe=100 hic=1.4k. obtain out AV
6. Give 1 application of a Cascode Amplifier.
7. Why RE is change by a current source in differential amplfier.
8. What is darlington pair?
9. What is overall current gain of Cascode amplfier?
10. What is the difference ranging from cascode and cascade amplifier?
11. What is common mode signal?
12. How does 1 describe small signals?
13. What is differential amplifier?
14. Obtain LF hybrid model of BJT for CE amplifier?
15. What is the action of bypass capacitor?
16. What is need for coupling capacitors?
17. What is meant by bootstrapping?
18. For CC amplifier draw hybrid model.
Part – B

19. Draw the small signal hybrid equivalent circuit of CE amplifier with fixed bias using approximate hybrid model and derive the expression for current gain, iinput impedance, voltage gain and output impedance

20. Draw the small signal hybrid equivalent circuit of CE amplifier with Voltage divider bias and with bypass capacitor (Ce) using approximate hybrid model. Derive the expression for current gain, input impedance, voltage gain and output impedance.

21. Draw the small signal hybrid equivalent circuit of CB amplifier with voltage divider bias using approximate hybrid model and derive the expression for current gain, input impedance, voltage gain and output impedance. presume the bypass capacitor [Cb] connected to the base terminal.

22. Draw the small signal hybrid equivalent circuit of CC amplifier with voltage divider bias using approximate hybrid model and derive the expression for current gain, input impedance, voltage gain and output impedance

23. Draw the small signal equivalent circuit of CS amplifier with voltage divider bias and with bypass capacitor (Ce). Derive the expression for input impedance, voltage gain and output impedance.

24. For the provided CE amplifier with Rs=1k, R1=50k , R2=2k, Rc=2k, Rl=2k, Re=500?, hfe=50, hie=1.1k, obtain out Ai, Zi, Av, Ais, Avs, Z0t

25. For the circuit shown beneath draw the small signal equivalent circuit. presume
hrb=0, hob=0, hib=25?, hfb= -0.99. compute Ai, Zi, Av, Avs, Z0t

26. Draw the circuit diagram of emitter coupled differential amplifier and find its dc analysis