Topic: Communication Systems
An amplifier has a gain of 50 dB, and noise figure of 10 dB. Assuming an ambient temperature of 300 K, what will be the total equivalent noise temperature at the input of the amplifier?
- A. 760 K
- B. 360 K
- C. 2700 K
- D. 3000 K
Answer: D. 3000 K
Explanation: Noise figure $F = 10\text{ dB}$, which corresponds to a linear ratio of $10^{10/10} = 10$.
Equivalent noise temperature of the amplifier $T_e = (F-1)T_0 = (10-1)300 = 9 \times 300 = 2700\text{ K}$.
Total equivalent noise temperature at the input $= T_{ambient} + T_e = 300\text{ K} + 2700\text{ K} = 3000\text{ K}$.