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Comps_SEM3_ECCF_MAY18 Mumbai University

NS: (1) Question No. 1 is compulsory

(2) Solve any three from remaining five Questions.

(3) Figures to the right indicate full marks.

Q1.

A: Draw input and output characterstics of BJT. State significance of DC load line. 5

B: For an AM DSBFC modulator with carrier frequency fc = 100KHz and a maximum

Modulating signal frequency fm = 5KHz, determine 5

i) Frequency limits for the upper and lower side bands

ii) Bandwidth

iii) Draw the frequency spectrum

C: Write a note on zero crossing detector using omp-amp and waveforms. 5

D: Compare class A and Class C amplifiers. 5

Q2.

A: Explain Superhetrodyne receiver with suitable diagram. 5

B: Implement summing operational Amplifier using inverting configuration of Op-amp. 5

C: For the emitter bias network of figure below, determine: 10

(a) Ib, (b) Ic, (c) Vce- (d) Vc+ (e) Rth Q.3

A: Explain generation of DSBSC using balanced Modulator along with its frequency

And power spectrum 10

B: With suitable waveforms explain how op-amp can be used as Differentiator 10

Q4.

A: For an AM DSBSC envelope with Vmax = 20V and Vmin = 4V; determine: 10

i) Peak amplitude of USF AND LSF

ii) Peak amplitude of carrier

iii) Peak change in the amplitude of envelope

iv) Modulation coefficient

v) Draw the AM Envelope

B: Differentiate between TDM and FDM 5

C: State Shannon’s Theorem and explain its significance 5

Q5.

A: Draw PAM, PWM and PPM waveforms in time domain using a sinusoidal signal

And explain in brief. 10

B: Define and explain in brief Amount of information, average information, information

Rate and channel capacity of a communication system. 10

Q6.

A: State significance of modulation in Communication. 5

B: Write a note on Pluse Code Modulation with waveforms. 5

C: Explain and give ideal values of following parameters of an Op-Amp: 10

i) CMRR

ii) Slew rate

iii) Offset Voltage

iv) Input Resitance

v) Output Impedance