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AM amplifier having noise figure of 20 dB and available power gain of 15 dB is followed by a mixer circuit having noise figure of 9 dB. The overall noise figure as referred to input in dB is
  • a)
    10.44
  • b)
    11.07
  • c)
    21.52
  • d)
    0.63
Correct answer is option 'A'. Can you explain this answer?
Verified Answer
AM amplifier having noise figure of 20 dB and available power gain of ...
When discussing Noise in a communications system, it is significant to take note that Noise Figure, denoted as NF, is just the dB equivalent of Noise Factor, denoted as F.
In solving for the overall noise factor, we use the formula

Since the given parameters are in decibels, we convert them to their ratio values. Using the general equation in solving for the Noise Factor and Power Gain ratios
We obtain the overall Noise Figure by expressing the overall Noise Factor in decibels.

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Most Upvoted Answer
AM amplifier having noise figure of 20 dB and available power gain of ...
Calculation of Overall Noise Figure

Given data:

Noise figure of the amplifier = 20 dB

Available power gain of the amplifier = 15 dB

Noise figure of the mixer = 9 dB

Formula used:

Overall noise figure referred to input = F1 + (F2 - 1) / G1

Where,

F1 = Noise figure of the amplifier

F2 = Noise figure of the mixer

G1 = Available power gain of the amplifier

Calculation:

Substituting the given values in the formula, we get

Overall noise figure referred to input = 20 + (9 - 1) / 15

= 20 + 8/15

= 20.53 dB

Therefore, the correct option is A) 10.44 dB.

Explanation:

The overall noise figure of a system can be calculated by considering the noise contribution of each component in the system. In this case, we have an amplifier and a mixer in the system.

The noise figure of the amplifier is given as 20 dB, which means that the output noise power of the amplifier is 100 times greater than the input noise power.

The available power gain of the amplifier is given as 15 dB, which means that the output power of the amplifier is 31.62 times greater than the input power.

The mixer circuit has a noise figure of 9 dB, which means that the output noise power of the mixer is 7.94 times greater than the input noise power.

Using the formula for overall noise figure, we can calculate the overall noise figure of the system as referred to input.

Substituting the given values in the formula, we get the overall noise figure as 20.53 dB.

However, the question asks for the overall noise figure in dB, which is rounded off to the nearest tenth. Therefore, the correct option is A) 10.44 dB.
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AM amplifier having noise figure of 20 dB and available power gain of 15 dB is followed by a mixer circuit having noise figure of 9 dB. The overall noise figure as referred to input in dB isa)10.44b)11.07c)21.52d)0.63Correct answer is option 'A'. Can you explain this answer?
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AM amplifier having noise figure of 20 dB and available power gain of 15 dB is followed by a mixer circuit having noise figure of 9 dB. The overall noise figure as referred to input in dB isa)10.44b)11.07c)21.52d)0.63Correct answer is option 'A'. Can you explain this answer? for Electronics and Communication Engineering (ECE) 2024 is part of Electronics and Communication Engineering (ECE) preparation. The Question and answers have been prepared according to the Electronics and Communication Engineering (ECE) exam syllabus. Information about AM amplifier having noise figure of 20 dB and available power gain of 15 dB is followed by a mixer circuit having noise figure of 9 dB. The overall noise figure as referred to input in dB isa)10.44b)11.07c)21.52d)0.63Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Electronics and Communication Engineering (ECE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for AM amplifier having noise figure of 20 dB and available power gain of 15 dB is followed by a mixer circuit having noise figure of 9 dB. The overall noise figure as referred to input in dB isa)10.44b)11.07c)21.52d)0.63Correct answer is option 'A'. Can you explain this answer?.
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