[time-nuts] Effect of EFC noise on phase noise

David davidwhess at gmail.com
Wed Aug 3 16:51:43 EDT 2016

On Wed, 3 Aug 2016 14:01:30 -0400, you wrote:

>Rick wrote:
>> Anyway, what I was led to believe is that
>> certain JEDEC 1N___ part numbers, with suffixes
>> indicating noise properties, from particular
>> vendors had much lower than average noise.  Thus
>> if a run of the mill zener diode has 1,000's of
>> nV/sqrtHz of noise, these "golden" diode might
>> have only 100's, or even dozens.
>I don't think the improvement was ever anywhere near two orders of 
>magnitude.  I'm not sure it was typically even one OOM.  But in any 
>case, the noise figure I quoted is the maximum rated noise for one of 
>those golden parts, not just some random ~6v zener diode.
>Best regards,

I wonder if the difference could be design and processing.

Avalanche type transient voltage suppressors and avalanche rated
rectifiers are optimized to have a very uniform junction so that all
areas of the junction break down at the same voltage.  Normal
rectifiers have a softer breakdown knee because different areas or
spots break down before others which leads to hot spots and poor power
handling capability.

How much would this affect the noise performance at low voltages where
a reference diode's temperature coefficient is well controlled?
Variations in processing might explain the wide variations in noise
and the golden parts.

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