Q. The noise voltage (Vn) and the signal bandwidth (B) are related as- Published on 15 Oct 15a. Vn is directly proportional to bandwidth
b. Vn is directly proportional to √bandwidth
c. Vn is inversely proportional to absolute temperature
d. Vn is inversely proportional to bandwidth
ANSWER: Vn is directly proportional to √bandwidth
Maximum Noise power is given by P
n = V
2/ R
R
L = R, for maximum power transfer from V
n to load resistor R
LIn the above figure, according to voltage divider method,
V = V
n/2
P
n = V
2/ R
= (V
n/2)
2/ R
= V
n2/ 4R
V
n2 = 4R P
nV
n = √(4R P
n)
Noise power P
n = KTB
Where
K = 1.381 × 10
- 23 J/K, joules per Kelvin, the Boltzmann constant
B is the bandwidth at which the power P
n is delivered.
T noise temperature
Therefore, V
n = √(4R KTB) or V
n is directly proportional to √bandwidth.
