Paul wrote:-
<<You should read about different types of noise -->
http://www.aikenamps.com/ResistorNoise.htm >>
Well, I read this webpage. Maybe you misunderstand. When they say
<<The thermal noise of a resistor is equal to:
Vt = SQRT(4kTBR)
where:
Vt = the rms noise voltage
k = Boltzmann's constant
T = temperature(Kelvin)
B = noise bandwidth
R = resistance >>
you are taking this to mean that the noise voltage is generated solely by
the temperature of the resistor whether or not there is a current flow and
this is what the equation seems to suggest; however, this is a sound
engineer's equation, not a physicist's. I think it means that if the
resistor is ACTUALLY resisting current, then the noise voltage is dependent
upon temperature and the "shot noise" depends upon the current. I put it to
you that when there is no current though the resistor, there is no
electrical noise at all. Still no free lunch.
Nick Palmer
