Elec Circuits & Comm. Fundamentals : Question Paper Dec 2014 - Computer Engineering (Semester 3) | Mumbai University (MU)

Elec Circuits & Comm. Fundamentals - Dec 2014

Computer Engineering (Semester 3)

(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.
1 (a) Mention five important specifications of ADC/DAC that are looked at while selecting them for any application.(5 marks) 1 (b) Discuss the factors that influence modulation index of an FM wave.(5 marks) 1 (c) Draw FET based Hartley and Colpitt Oscillator. What is the frequency of oscillation if
i) L1=10 mH, L2=10 mH and C=0.1 ?F for Hartley tank circuit.
ii) L=10 mH, CI=0.1 ?F and C2=0.1 ?F for Colpitt tank circuit.
(5 marks)
1 (d) A public address system is connected to a microphone that has a maximum output voltage of 10mV. The microphone is connected to a 10 watt audio amplifier system that is driving an 8 Ohm speakers. The voltage amplifier is non-iverting op-amp circuit. Calculate the maximum voltage gain for the voltage amplifier stage and determine the resistor values to obtain the desired gain. Assume the power amplifier stage has a voltage gain of 1.(5 marks) 2 (a) With proper circuit diagrams and transfer characteristics indicating Q-points do comparison of JFET bias circuit in detail.(10 marks) 2 (b) Find R1 and R2 in the lossy integrator so that the peak gain is 20 dB and the gain is 3dB down from its peak when ?=10,000 rad/s. Use capacitance of 0.01 ?F.(10 marks) 3 (a) Sketch a block representation for an n-channel JFET, showing bias voltages, depletion regions, and current directions. Label the devices= terminals and explain its operation. Explain the effect of increasing levels of negative gate source voltage. Also sketch a typical drain characteristics for VOS=0 for an n-channel JFET. Explain the shape of the characteristics, identify the regions, and indicates the important current and voltage levels.(10 marks) 3 (b) Draw the spectrum of an amplitude modulated wave and explain its components.(5 marks) 3 (c) Draw and explain OP-amp non inverting comparator. Draw input and output waveforms for Vref positive and also for Vref negative.(5 marks) 4 (a) Explain the working of a superheterodyne receiver with the help of a neat block diagram. Show the waveform at the ouput of each block.(10 marks) 4 (b) What is DSBSC wave? Explain its generation using balanced modulator.(10 marks) 5 (a) Draw the PAM, PWM and PPM waveforms in time domain assuming a sinusoidal modulating signal. Explain them in brief.(10 marks) 5 (b) The maximum deviation allowed in a FM broadcast system is 75 kHz. If the modulating signal is a single tone sinusoidal of frequency 15 kHz, find the bandwidth of the FM signal. How does the bandwidth change if the modulating frequency is doubled?(5 marks) 5 (c) How is adaptive delta modulation superior to delta modulation?(5 marks) 6 (a) What do you understand by signal multiplexing? Explain TDM and FDM with suitable examples.(10 marks) 6 (b) With neat circuit diagram explain the use of PLL as phase shifter.(5 marks) 6 (c) Give advantages and disadvantages of SSB over full carrier DSB amplitude modulated wave.(5 marks)


Continue reading

Find answer to specific questions by searching them here. It's the best way to discover useful content.

Find more