I have a problem finding information on the subject of noise level relationship to current flowing through a HV zener in the breakdown mode.
Somehow the manufacturers don't elaborate on the noise issues in Zeners.
The only graph I found so far is Fig. 2 in the 5612568 patent.
I'd post a link to it, but I am new, so the system prevented me from posting direct link. It is on freepatentsonline website as 5612568.pdf
I also found a paper which might be interesting, but its paid per view so no luck here. ["Noise studies in internal field emission diodes"; G. Lecoya, R. Alabedraa and B. Barbana]
Elsewhere I read there is a significant noise increase at the very low levels of current however the current increase will also increase the noise levels. [exactly as shown in the graph in the patent mentioned previously]
So I am very interested in finding that current minimum - learning the optimal current value for a 200V zener so the noise is at the minimum. My application is basicaly a voltage reference circuit with a resistor in series so I can set it at any current I wish and it will stay there at all times. I suspect the minimum noise density might be around 250 microampers for a typical product like 2EZ200, 1N5388B, 1N5281B, 1N5956B, Z4KE200, ZGL41-200, BZX85-C200 - but I would prefer to be sure. Can anyone help?