An attenuator with loss L >> 1 is followed by an amplifier with noise figure F and gain Ga = L.
a. Find the noise figure of the cascade at temperature T0.
b. Consider the cascade of two identical attenuator-amplifier stages as in part (a). Determine the noise figure of the cascade at temperature T0.
c. Generalize these results to N identical attenuators and amplifiers at temperature T0. How many decibels does the noise figure increase as a result of doubling the number of attenuators and amplifiers?