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ECE Objective Questions { Microwave Devices and Circuits }



22. It spectrum density of thermal noise at room temperature is 4 x 10-21 W/Hz, then available noise power for a bandwidth of 1 MHz is ___ watt.
A. 4 x 10-27
B. 4 x 10-21
C. 4 x 10-15
D. 4 x 10-9

23. Ceramic filters
A. are used for single-sideband generation
B. use magnetostrictive materials in their construction
C. use a lattice configuration just like crystal filters
D. are similar in construction to mechanical filters

24. The value of thermal noise voltage for a resistor of 4 K for a bandwidth of 1 MHz and 'spectrum density of 4 x 10-21 W/Hz is
A.0.8
B.8
C.0.64
D.80

25. Indicate the noise whose source is in a category different from that of the other three.
A. solar noise
B. cosmic noise
C. atmospheric noise
D. galactic noise

26. Ten telecommunication links working in tandem each have an S/N ratio of 60 dB. Their overall S/N ratio is ___ dB.
A.20
B. (60)1/2
C.50
D.60

27. Noise figure is used as figure-of-merit of
A. oscillator
B. amplifier
C. modulator
D. isolator

28. Indicate which one of the following types of noise does NOT occur in transistors
A. shot noise
B. flicker noise
C. partition noise
D. resistance noise

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