Basic Electronics Engineering 2018 Question Paper — Government Colleg…
The 2018 Basic Electronics Engineering previous year question paper (Government College of Engineering and Technology, Jammu), with every question and its marks.
- University: Government College of Engineering and Technology, Jammu
- Subject: Basic Electronics Engineering
- Course: Basic Electronics Engg.
- Year: 2018
- Paper: end-term
- Duration: 180 minutes
- Total marks: 100
Instructions
- Attempt five questions in all, selecting at least two questions from each section.
- Use of calculator is allowed.
- Assume suitable data, wherever missing.
Questions
SECTION—A
- Q1. (a) In a semi-conductor at room temperature, the intrinsic Carrier Concentration and resistivity are $1.5 \times 10^{16}/\text{m}^3$ and $2 \times 10^3 \; \Omega\text{-m}$ respectively. It is converted into an extrinsic semiconductor with a doping concentration of $10^{20}/\text{m}^3$. For the extrinsic semi-conductor, calculate the (i) Minority carrier concentration (ii) Minority carrier concentration when its temperature is increased to a value at which the intrinsic carrier concentration doubles. Assume that mobility of minority and majority carriers to be same. (10) (b) Define and explain "The Mass-Action Law" with reference to Semiconductor material. Explain the extrinsic semiconductors and find out the carrier concentrations in P and n- type of semiconductors. (10) [20 marks]
- Q2. (a) Explain the construction, working & V-I characteristics of a Tunnel diode. (10) (b) Explain the capacitances in the diode under forward and reverse bias conditions. Calculate the barrier capacitance of a Ge Pn junction whose area is $1 \text{ mm} \times 1 \text{ mm}$ and whose space charge thickness is $2 \times 10^{-4} \text{ cm}$. The dielectric constant of Ge is 16. (10) [20 marks]
- Q3. Draw and explain the working of a Centre-tapped full wave rectifier with reference to different waveforms. Drive the expressions for its DC value of voltage, ripple factor & rms value of voltage. A centre-tapped full wave rectifier has $R_L = 1\text{ k}\Omega$. Each diode has a Forward resistance $r_f = 10\Omega$. The voltage across half the secondary winding is $220 \text{ Sin } 314t$. Find Peak, average, & rms values of current. Also find PIV rating of each diode & ripple factor of the rectifier. (20) [20 marks]
- Q4. (a) Draw and explain the operation of Shunt, series clipper ckts. Draw and explain the operation of clamper ckt also. (12) (b) Draw the full wave rectifier ckt with capacitor filter circuit and explain how the filter ckt removes the ripple contents in the output wave forms? (8) [20 marks]
SECTION—B
- Q5. (a) Draw and explain CE Transistor input & output characteristics & hence explain the different regions of operation of the transistor and discuss the effect of base width modulation on the output characteristics. (12) (b) Starting from the equation $I_C = \alpha I_E + I_{CO}$ for the transistor operating in the active region, drive the expression for Collector Current ($I_C$) of CE Transistor operating in Active region and the reverse Saturation current $I_{CEO}$ . (8) [20 marks]
- Q6. Why do we fix the Q-pt at the centre of the characteristics of a BJT. List the objectives of the biasing ckt. Draw the voltage divider biasing ckt and drive the expression for its operating point. Find the $I_B$, $I_C$, $V_{CE}$ & $V_C$ for the ckt of Fig. 1 For the circuit shown in Fig-1. [20 marks]
- Q7. (a) What are the various blocks of a receiver system used in radio Communication? Explain each one of them in detail. (10) (b) Draw the functional block diagram of a digital communication system and explain the elements of such system. (10) [20 marks]
- Q8. (a) Explain the various frequency bands used for Communication. (8) (b) What do you mean by "Communication"? With functional diagram, Explain the various blocks of a Communication System. (12) [20 marks]