 MORE IN Elec Circuits & Comm. Fundamentals
MU Computer Engineering (Semester 3)
Elec Circuits & Comm. Fundamentals
May 2015
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) Draw and explain FET based Hartley and Colpitt Oscillator.
5 M
1 (b) Comment on the following ADC/DAC specifications
i) Resolution
ii) Linearity
iii) Accuracy
iv) Settling Time
v) Stability.
5 M
1 (c) How is adaptive data modulation superior to delta modulation?
5 M
1 (d) Discuss the factors that influence modulation index of an FM Wave.
5 M

2 (a) A sketch a block representation for an n-channel JFET, showing bias voltage, depletion regions, and current directions. Label the device terminals and explain its operation. Explain the effect of increasing levels of negative gate-source voltage.
Also sketch a typical drain characteristics for VGS-0 for an n-channel JFET. Explain the shape of the characteristics, identify the regions, and indicate the important current and voltage levels.
10 M
2 (b) Design an op-amp differentiator that will differentiate an input signal with tmax=100 Hz. Draw the output waveform for a sine wave of 1V peak at 100 Hz applied to the differentiator. Also repeat it for square wave input.
10 M

3 (a) Explain the different methods of biasing JFET along with their characteristics in detail.
10 M
3 (b) Explain any one technique used of conversion of analog signal to digital with ADC.
5 M
3 (c) Draw and explain op-amp inverting comparator. Draw input and output waveform for Vref>0 and also for Vref<0.
5 M

4 (a) Draw Foster Seeley Descriminator with circuit diagram and explain its working with phasor diagrams?
10 M
4 (b) What is DSBSC wave? Explain its generation using balanced modulator.
10 M

5 (a) Draw the PAM, PWM and PPM waveform in time domain assuming a sinusoidal modulating signal. Explain them in brief.
10 M
5 (b) In an AM radio receiver the loaded Q of the antenna circuit at the input to the mixer is 100. If the intermediate frequency is 455 Khz, calculate the image frequency and its rejection at 1MHz.
5 M
5 (c) With neat circuit diagram explain the use of PLL in frequency translator.
5 M

6 (a) What do you understand by signal multiplexing? Explain TDM and FDM with suitable example.
10 M
6 (b) Draw the spectrum of an amplitude modulated wave and explain its components.
5 M
6 (c) Compare class A and Class C power amplifiers.
5 M

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