## EC2151 EDEC part -B important questions ( all five units )

EDC IMPORTANT  QUESTIONS
1. ENERGY BAND THEORY OF SOLIDS

1. Hall effect and its applications
2.  Continuity equation
3.  Diffusion and drift currents
4.  Problems on Î±,j, n, u, p.

2.  Semiconductor diodes

1.  Diode V-I characteristics and formula for diode current.
2.  Diffusion capacitance and transition capacitance (definitions and derivations)
3.  All special diodes with construction, working, characteristics and applications.

3.  Diode rectifiers

1. All rectifiers working, circuits, waveforms derivations of formulae with and without filters.
2.  Compare three rectifiers.
3.  Problems

4.  Bipolar junction transistor

1.   C.B,C.E  and  C.C basic configurations and characteristics (I/P and O/P characteristics)
2.  Compare three amplifier configurations w.r.t voltage gain, current gain, and power gain, input and    output impedances.
3. What is base width modulation and explain the corresponding effects.
4. Discuss about transistor current components.
5. Derive relations among Î±, Î², and Î³.

5. JEET

1.  Explain working of NJFET and give it characteristics.
2.  Compare BJTS and UJTS.
3.  Obtain small signal low frequency model for a FET.
4.  Derive formulae like  Î¼= gm rd, vp , gm , Idss, gmo (see worked out problem).
5.  Mosfet – Enchanemode and depletion mode working and characteristics ( with neat diagrams).
6. Explain FET biasing.
7.  Explain FET as VVR.

6. TRANSISTOR BIASING CIRCUITS
1.   Explain fixed bias and self bias techniques in a BJT with circuits.
2.  What is thermal runaway and how to avoid it(condition).
3.  Describe bias compensation circuits (diode compensation for V BE and I co) (thermistor    compensation for Ico).

7. SMALL SIGNAL LOW FREQUENCY TRANSISTOR BIASING CIRCUITS.

1.   Obtain h-parameter mode (small signal low frequency model) for a transistor and draw h- parameter model for CB, CE and CC amplifiers.
2.  Derive Av, AVs, AI, AIs, Zi and Yo for a transistor amplifier in terms of h-parameters (Exact formulae).
3. See approximate formulae also.
4.  See conversion formulae, problem may be given on cc.amplifier with CE h-parameters given in the data.
5.  Derive Ri and Ai of a Darlington amplifier.
6.  Prove that CE with RE is more stable.
7. What is a bypass capacitor?
8.   Rc coupled amplifier and frequency response, derivations of AVi, AVm and AVh.
9.  Describe high frequency model (hybrid-Ï€) model of a BJT.
10.  Millers theorem and its dual- problems