[time-nuts] Distribution amplifier phase noise

John Ackermann N8UR jra at febo.com
Thu Mar 14 08:06:27 EDT 2013


Ulrich, I'm on the run right now, but I've done measurements of the HP 5087, TADD-1, Spectracom 8140-series line amp, and a new protoype ULN buffer amp.  I'll post the links later today.

John

On Mar 14, 2013, at 6:59 AM, "Ulrich Bangert" <df6jb at ulrich-bangert.de> wrote:

> Gentlemen,
> 
> although it has been discussed here by Bruce et al how the noise floor of
> integrated distribution amplifiers designs may compare to discrete designs I
> have never seen a *real* phase noise measurement of a *real* amplifier here.
> 
> My own measurements on a DIY AD8007 based distribution amplifier indicate a
> noise floor of abt. -160 dBc @ 100 kHz which may not meet the specs of the
> absolutely top line of oscillators by some 15 dB but is well in reach of
> Bruce's predictions for integrated designs.
> 
> Did any of you Timepod owners make measurements of your own on amplifier
> noise? Please note that I am not only out for the noise floor specs. Instead
> I am specially interested in specs for power supply induced spurs.
> 
> I just received an article covering ultra low noise oscillators to be found
> here:
> 
> http://www.crystek.com/documents/appnotes/ImpactUltralow.pdf
> 
> Clearly the phase noise diagram shows a power induced spur @ -100 dBc. Is
> this the measure for the amplifier to take care for? I.e. if the amplifiers
> has spurs down -120 dBc, is that good enough? 
> 
> Or to put it another way: What is the best phase noise that we can expect
> from an amplifier concerned power supply induced spurs? Can it be that the
> spurs to be seen are not a problem of the amplifier itself but are inherent
> to the measurement setup? If so, is there a recommended setup to minimize
> such problems?
> 
> Thanks in advance for your suggestions. I appreciate the expertise in this
> group a lot!    
> 
> Ulrich Bangert
> www.ulrich-bangert.de
> Ortholzer Weg 1
> 27243 Gross Ippener 
> 
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