ST02v03

# ST02v03 - Types of electrical noises(i Johnson Noise...

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1 Types of electrical noises (i) Johnson Noise Johnson noise occurs in any device that dissipates power, such as resistor, hence it is very common. Principle of equipartition of energy states: For a system in thermal equilibrium with its surroundings : The mean kinetic energy of each degree of freedom is ½ kT , where k =Boltzmann’s constant (1.4×10 J/K) 1. 1 joule = 0.2388 calorie. It is named after James Joule. When the point of application of a force of one Newton moves, in the direction of the force, a distance of one metre. 2. Boltzmann's constant ( k ): The number that relates the average energy of a molecule to its absolute temperature. 3. T = the absolute temperature (thermodynamic temperature): A measure, in Kelvin (K), proportional to the thermal energy of a given body at equilibrium. -23

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Note 1: A temperature of 0 K is called "absolute zero," and coincides with the minimum molecular activity ( i.e. , thermal energy) of matter. Note 2: Thermal noise power, per hertz, is equal throughout the frequency spectrum, depending only on k and T . Note 3: For the general case, the above definition may be held to apply to charge carriers in any type of conducting medium. The electrons in a conductor thus have a mean square velocity (in one
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## This note was uploaded on 01/23/2012 for the course EE 4580 taught by Professor Gu during the Fall '10 term at LSU.

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ST02v03 - Types of electrical noises(i Johnson Noise...

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