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

27. Draw the circuit diagram of a differential amplifier using BJTs, define common mode and differential modes of working. Derive expression for Ad , Ac and CMRR.
28. With neat circuit diagram discuss working of Cascode Amplifier.
29. For the provided CE amplifier with voltage divider bias has the subsequent specifications : Rs=1k, R1=45k , R2=5k, Rc=2k, Rl=2k, Re=500?, hfe=50, hie=1.1k, obtain out Ai, Zi, Av, Ais, Avs, Z0t



Unit - IV
PART –A
1. Explain the effect of coupling capacitors.
2. Explain the effect of bypass coupling capacitors.
3. Discuss the internal BJT capacitances and discuss their effects.
4. In an ac amplifier, which capacitance affect the low frequency gain?
5. How is the high frequency gain of an amplifier limited?
6. When can coupling and bypass capacitors be neglected?
7. Express power gain in dB.
8. Express voltage gain in dB.
9. Define critical frequency.
10. Convert the power gain of 25 to dB.
11. How much increase in true voltage gain corresponds to +12dB?
12. How do you determine the mid range voltage gain?
13. Describe how RC circuits affect gain.
14. For the voltage divider biased capacitor-coupled amplifier, identify the 3
high-pass RC circuits.
15. Determine the lower critical frequency of the input RC circuit.
16. Discuss the gain roll-off in terms of dB/decade and dB/octave.
17. Determine the phase shift of the input RC circuit.
18. Determine the lower critical frequency of the output RC circuit.
19. Determine the phase shift of the output RC circuit.
20. Determine the lower critical frequency of the bypass RC circuit.
21. Describe a Bode plot.
22. A certain amplifier exhibits three critical frequencies in its low frequency
response. fc1 = 130Hz, fc2 = 167 Hz and fc3 = 75Hz. What is the
dominant critical frequency?
23. A certain RC circuit has an fc = 235 Hz, above which the attenuation is 0 dB.
What is the dB attenuation at 23.5 Hz?
24. Determine the Miller input capacitance of a BJT or an FET.
25. Determine the Miller output capacitance of a BJT or an FET.
26. Determine Cin(Miller) if Av = 50 and Cbc = 5pF.
27. Determine Cout(Miller) if Av = 25 and Cbc = 3pF.
28. State Millers theorem.
29. Describe how internal capacitances affect the gain of BJT amplifier.
30. Identify the high frequency input RC circuit in a capacitively coupled
amplifier and determine the upper critical frequency of the high frequency

Earning:   Approval pending.