In article , Eeyore
wrote:


Ian Bell wrote:

So apart from the possible variation of gm with anode current, the
noise added by a triode seems to to fairly independent of anode
current. This seems strange to me since shot noise is caused by random
fluctuations in anode current so I would expect higher anode currents
to produce higher noise.

Not because of the shot effect for sure.

Erm... the shot noise level rises with the current level. The reasons for
this are well explained by theory.

A higher anode current means the relative size of the unit electronic
charge is actually *smaller* in influence.

For an individual charge, yes. The snag is that there are many more of them
when the current is higher, and it is the statistics that matter. The
result is that with a 'Normal' distribution of statistics the shot noise
level rises with the mean current level. Standard result regardless of
device type. Also comfirmed in general observations. Indeed, I think the
theory for this, and the measurements, we established long before solid
state devices gain became common.

So, yes, I'd expect the shot noise contribution to rise with bias current.

Slainte,

Jim

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