Download Aptitude Crack
img not found img not found

Communication Systems - Engineering

Q1:

The noise figure of individual stages of a two stage amplifier is 2.03 and 1.54 respectively. If gain of first stage is 62, the overall noise figure is

A 2.03

B 2.055

C 3.05

D 6.05

ANS:B - 2.055

Noise figure is different from the noise factor. The total noise factor can be calculated using the Friis formula for cascaded amplifiers.

Total noise factor = f1+((f2-1)/A1), where f1 and f2 are the respective noise factors for the individual stages.

From that, the total noise figure can be solved by: Total noise figure = 10 log (Total noise factor).