[time-nuts] Phase noise measurement (was - no subject)

[Adrian]

Rick,

thank you again for having pointed me to the AMC123 that were just 
available when you mentioned them.
Part of the magic is the 10 dB gain and typical +23 dBm output.
So, you don't saturate it with a 10811, which would be bad in terms of 
phase noise, and, on the other hand, if you overdrive it accidentally, 
there is no risk to damage the +23 dBm mixer (phase detector) in the 
11848A test set.
There are some other interesting Anzac models featuring the lossless 
feedback design, but this one fits best.

I was lucky to find some Q-Bit anps (QBH-137 and 138) that are based on 
an almost identical patent but, with 12 to 15 dB, have more gain and 
maybe slightly higher PN.

Anzac patent: 3,624,536 which is the original David E. Norton patent 
from 1971.
Q-Bit patent: 4,042,667 from 1977 
http://www.freepatentsonline.com/4042887.pdf

To comment on the Mini Circuits amp, for my needs it has way too much 
gain and +5 dBm 1 dB compression makes it completely useless for PN 
measurement purposes.

Adrian


Rick Karlquist schrieb:
> It is good that you asked this FAQ.  Basically, what is magic
> about the AMC-123 is that it has certifiably low phase noise,
> guaranteed by design and characterization, although not specified
> by Anzac.  The other 99.9% of amplifiers that seem plausible, like
> this one, do not have the sophisticated negative feedback scheme
> of the AMC-123, and likely do NOT have good enough phase noise.
> In any event, we have zero information about the phase noise of
> this Mini-Circuits amplifier.  Having a low noise figure is necessary
> but not sufficient to have good phase noise.
>
> Of course you could always get lucky.  But then you have to also
> build an amplifier phase noise measurement system, which generally
> entails a line stretcher.
>
> Again, thank you for asking this question.  It comes up often.
>
> Would anyone else like to suggest a known good low phase noise
> buffer amplifier?  Maybe something from a Fred Walls paper?
>
> Rick Karlquist N6RK
>
>
> Mark J. Blair wrote:
>    
>> On Aug 20, 2010, at 11:17 AM, Rick Karlquist wrote:
>>      
>>> On the 10811 production line, they would use Anzac AMC-123 amplifiers
>>>        
>> How does this amplifier look for this application?
>>
>> http://minicircuits.com/pdfs/ZFL-500LN.pdf
>>
>> If I understand the specifications properly, the noise figure is better
>> and it has higher reverse isolation and higher gain, but a lower output
>> intercept point.
>>
>>
>>
>> --
>> Mark J. Blair, NF6X<nf6x at nf6x.net>
>> Web page: http://www.nf6x.net/
>> GnuPG public key available from my web page.
>>
>>
>>
>>
>>
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>
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