[time-nuts] SMD TADD-1 distribution amplifier

[Charles Steinmetz]

Bruce wrote:

>Such blanket statements aren't a particularly useful guide unless 
>calibrated by measurements.
>*     *     *
>The input voltage noise @1Hz can't be used directly to estimate the 
>PN noise at 1Hz offset.

My message referred readers to previous list messages for a more 
detailed explanation, and recommended a particular search term.  If 
you had done that, you would have gone straight to a message in which 
I explained that one cannot directly correlate noise density 
measurements with PN because each amplifier implementation has its 
own specific mechanism of AM-PM conversion.

That said, when one limits the discussion to inductorless, monolithic 
amplifiers, I have not observed anywhere near the quantitative 
differences between amplifiers (with respect to AM-PM conversion) 
that it would take to equalize the PN contributions of two amplifiers 
whose baseband noise voltage densities differ by more than 40dB (as 
is the case when comparing the MAX477/AD8055 with available low-noise 
parts).  So, yes, when a part has an input voltage noise density 
*that* much worse than other available parts, one can conclude 
without detailed measurements that it is not a promising candidate 
for use as a low-PN amplifier.

Best regards,

Charles