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Encyclopedia > Noise temperature

Noise temperature: At a pair of terminals, the temperature of a passive system having an available noise power per unit bandwidth at a specified frequency equal to that of the actual terminals of a network.


The noise temperature of a simple resistor is the actual temperature of that resistor. The noise temperature of a diode may be many times the actual temperature of the diode.


  Results from FactBites:
 
Noise Figure - Microwave Encyclopedia - Microwaves101.com (898 words)
Signal to noise ratio always worsens from input to output due to entropy or one of those other depressing laws of the universe; as the S/N ratio at output is less than S/N ratio at input, noise factor is always greater than unity.
The "290" in the expression is used to denote a standardized temperature, which in this case is close to room temperature (290 K is an IEEE standard).
Note that noise temperature of an amplifier is not directly related to the temperature of an amplifier.
Reduce noise in distributed communications systems (2846 words)
Essentially, noise temperature is the ratio between noise at the terminals of a network and the noise that exists at the reference temperature (290§K) of a totally passive system.
Noise factor, then, is a multiplier used to predict the amount of amplifier noise power output compared with the noise power output that would occur in a perfect amplifier under the same conditions.
Noise characteristic is input-based The noise characteristic of any device is fundamentally set by its input network, whether it is the base of a transistor or the first stage of a complex amplifier or receiver.
  More results at FactBites »


 

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