FUNDAMENTAL OF ELECTRONICS

FUNDAMENTAL OF ELECTRONICS ENGINEERING
SEM-I, 2011
UTU PREVIOUS YEAR QUESTION PAPERS

Time: 3 hours

Total marks: 100

Attempt any four parts:

1. What happens to the conductivity of semiconductors with the rise in temperature? Compare with the conductivity of metals.
2. What is meant by Fermi level in semiconductor?
3. At room temperature, the reverse saturation current is 0.3µA when a reverse bias is applied to a Ge diode. Find the value of current flowing in diode when 0.15V forward bias is applied.
4. Define conductivity. Derive the expression of conductivity in intrinsic and extrinsic semiconductors.
5. Explain the formation of depletion layer in a p-n junction diode.
6. Explain the transition capacitance and diffusion capacitance of a p-n junction diode.

Attempt any two of the following parts:

1. Differentiate between clippers and clampers circuit. Discuss biased clippers.
2. With a neat diagram, explain the working of C-filter.
3. Discuss different rectifier circuits. The turns ratio of a transformer used in a half wave rectifier is N₁:N₂=12:1. The primary is connected to power mains 220V, 50Hz. Assuming the diode resistance in forward bias to be zero, calculate the dc voltage across the load. What is the PIV of the diode?

Attempt any two of the following parts:

1. Draw and explain the input and output characteristics of CE configuration of BJT. Indicate all regions of operation.
2. Define with respect to BJT the followingI_CEO, I_CBO, α, β, stability factor.
3. Derive the hybrid parameter expression of A_I, R_I, A_v, R_o, A_vs, A_IS for CE amplifier.

Attempt any two of the following parts:

1. Explain the working of and characteristics of n channel JFET.
2. Find the Q point and V_DS, for the fixed bias configuration using mathematical and graphical approach. Given V_DD= 15V, R_D= 2kΩ, R_G= 2MΩ, V_GG= 2V, I_DSS= 10mA, V_p= -6V.
3. Discuss and draw the drain and transfer characteristic of p channel D-MOSFET.

Attempt any two of the following parts:

1. Explain the following:(i) De Morgan’s theorem(ii) Universal gates.
2. Enlist the ideal op-amp characteristics. What is the drawback of open loop configuration? Explain op-amp as integrator and differentiator.
3. (i) Subtract (11011)₂ from (11101)₂ using 1’s compliment method.(ii) Add (6E)₁₆ from (34)₁₆(iii) Minimise using K-map Y=∑m(1,3,7,11,15) + d(0,2,5).

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