[time-nuts] State of the art of crystal oscillator measurements

KA2WEU at aol.com KA2WEU at aol.com
Thu Aug 11 19:10:21 EDT 2016

    Values  of kT at 25°C (298 K) Units  kT = 4.11×10−21 _J_ 
(https://en.wikipedia.org/wiki/Joule)   kT = 4.114 pN⋅nm  kT = 9.83×10−22 _cal_ 
(https://en.wikipedia.org/wiki/Calorie)   kT = 25.7 _meV_ 
(https://en.wikipedia.org/wiki/Electron-volt)    Related quantities  kT/hc = 200 cm-1  kT/e = 25.7 _mV_ 
(https://en.wikipedia.org/wiki/Volt)   RT = kT ⋅ _NA_ 
(https://en.wikipedia.org/wiki/Avogadro's_number)  = 2.479 _kJ⋅mol-1_ 
(https://en.wikipedia.org/wiki/Joule_per_mole)   u = 0.593 _kcal⋅mol−1_ 
(https://en.wikipedia.org/wiki/Kilocalorie_per_mole)   _h_ (https://en.wikipedia.org/wiki/Planck_constant) 
/kT = 0.16 _ps_ (https://en.wikipedia.org/wiki/Picosecond) 
In a message dated 8/11/2016 7:02:13 P.M. Eastern Daylight Time,  
john at miles.io writes:

Right,  I'm speaking specifically of L(f).  The device being driven by the  
oscillator doesn't care about the NF of the driver stage, only what a PN  
analyzer would measure at the output jack.

For any 50-ohm source, the  practical L(f) floor is -177 dBm/Hz - the 
carrier power in dBm.  No  oscillator with an output of 0 dBm can be quieter than 
-177 dBc/Hz at any  offset, but an oscillator that puts out +20 dBm could 
approach -197  dBc/Hz.

Given a proverbial black box containing a +17 dBm oscillator  that measures 
-195 dBc/Hz at 100 kHz, the interesting question is, "What's in  the box?"  
There could be a passive resonator that's shaving off the  broadband noise 
after the last active stage without contributing additive  noise of its own. 
 Another possibility might be cross-spectral collapse  due to correlated 
thermal noise from the splitter.   

--  john, KE5FX
Miles Design LLC

> -----Original  Message-----
> From: time-nuts [mailto:time-nuts-bounces at febo.com] On  Behalf Of KA2WEU--
> - via time-nuts
> Sent: Thursday, August 11,  2016 2:37 PM
> To: time-nuts at febo.com
> Subject: Re: [time-nuts]  State of the art of crystal oscillator 
> NO, the  maximum  possible noise dynamic range is ( 177 +  Pout)   [dBm]  
> Transistor large signal NF ( dB),
>  the  signal to noise ration is dimensionless !!!!

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