[time-nuts] how to find low noise transistors

[KA2WEU at aol.com]

The first reference is audio only, no RF component, 
 
Ref 2 is questionable as the SSB analyzer lacks the low frequency dynamic  
range, at 1 Hz and below it should be more like 40dB/Hz , a 100 MHz crystal  
oscillator as a test would have ben better . But he is much more hones 
using  AF=2, maybe slightly off, but not 1 as some use.
 
About CEL :  

FOR SSB noise not useful but at least it shows that AF and KF , both, are  
bias dependent, must forget this .
 
SILVACO page 112 again is low frequency modeling, not applicable for RF,  
one need to know the AM/PM conversion.
 
This is a real tough subject and  most approaches are incorrectly, use  
curve fitting or test equipment with not enough dynamic range ... 
 
 
73 de Ulrich , N1UL
 


 
 
In a message dated 7/19/2015 10:36:10 A.M. Eastern Daylight Time,  
azelio.boriani at gmail.com writes:

For a  method to extract AF and KF try  this:
<http://joerg-berkner.de/Fachartikel/pdf/2000_AKB_Berkner_1f_noise.pdf>

see  also
<http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=2270&context=etd>
from  page 55, on the parameter extraction for the BJTs

usually AF is greater  than 1, as you can see in this appnote from  CEL:
<http://www.cel.com/pdf/appnotes/an1026.pdf>

A SILVACO  appnote on how to model for SPICE2 for 1/f (from page  45):
<http://www.silvaco.com/content/kbase/noise_modeling.pdf>

On  Sun, Jul 19, 2015 at 4:59 AM, John Miles <john at miles.io>  wrote:
>
>> -----Original Message-----
>> From:  time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of  
KA2WEU--
>> - via time-nuts
>> Sent: Saturday, July 18, 2015  3:40 PM
>> To: time-nuts at febo.com
>> Cc:  akpoddar at synergymwave.com; Alexander.Roth at rohde-schwarz.com
>>  Subject: Re: [time-nuts] how to find low noise  transistors
>>
>>  BFG540
>>
>>
>
> That's what I mean -- both  BFG540 and BFG591 have been discontinued by 
NXP.  Guess they don't sell  enough of them these days.
>
> -- john, KE5FX
> Miles Design  LLC
>
>
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