[time-nuts] Phase noise test set reference articles

Alexander Pummer alexpcs at ieee.org
Tue Mar 29 20:06:50 EDT 2016


and here is with very good literature: 
https://www.google.com/search?q=Haas+Mixer+noise&ie=utf-8&oe=utf-8#q=Maas+Mixer+noise

On 3/29/2016 3:28 PM, Gerhard Hoffmann wrote:
> Am 29.03.2016 um 16:53 schrieb Charles Steinmetz:
>>
>> (10) Phase_detector_with_low_flicker_noise_BARNES_etal_NIST_2011: 
>> Describes a DIY double-balanced mixer phase detector using 
>> diode-connected 2N2222 transistors.  [Note that only the flicker 
>> noise is improved -- the white noise floor is actually significantly 
>> higher than with DBMs using diodes.  NB: There are much better 
>> transistors than the 2N2222 for this application.]
> .. and they are NOT really used as diodes. They are used as switching 
> transistors with most current flow C-E, saturation enforced.
> That turns faster on than the diode exp-law.
> Somewhere they also say that they use 50 Ohm load.
>
> I really wonder where all that ring mixer noise is to come from. The 
> diodes are just switches, the transformers
> have close to no loss and behave properly in power dividers, and even 
> when the diodes are resistors for a moment,
> their noise is only half-thermal.
>
> I find it easy to believe that high power mixers produce more noise. 
> In that app note by Watkins-Johnson that everybody copies,
> there it is clearly shown that they may use resistors to generate bias 
> voltages.
>
> If I use two 1:4 Wilkinsons, 4 low power ring mixers and put the 
> outputs in series, will it also turn worse? I don't think so.
>
> Are there anywhere musings about the equivalent noise resistance of a 
> ring mixer IF output?
> If it is really something like 500 Ohms, even a single AD797 may be 
> excessively over-optimized
> for voltage, and not current noise.
>
> regards, Gerhard
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