Question

An amplifier operating over the frequency range of 470 to 480 KHz has 300KS input resistor.
Calculate the rms noise voltage at the input of this amplifier of the ambient temperature is 272​

Answer 1

Explanation:

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Answer 2

Given:

B = 300K Ω

R = 480 - 470 =10KHz

T = 272​ °C

To find:

RMS noise voltage =?

Explanation:

RMS noise voltage is given by

$\displaystyle E_n = \sqrt{4KTRB}$

where

K = Boltzmann's constant = 1.38 $\times 10^{-23$ J\K

T = absolute temperature

R = input resistance

B = noise bandwidth

Put given values in above equation

$\displaystyle E_n$      = $\DISPLAYSTYLE \sqrt{4 \times 1.38\times10^{-23}\times272\times10\times10^3\times300\times10^3}$

     = 671.14 $\times10^{-8$

     = $6.71 \times10^{-6$

$\displaystyle\mathbf{ E_n = 6.71 \mu \d\B\m}$ dBm