Micpre of Graham
in [Design]
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From: Eeyore on 22 Mar 2007 19:54 Fred Bartoli wrote: > Eeyore a �crit : > > > > John Larkin wrote: > > > >> But metal film resistors don't have shot noise current. > > > > You mean they're not supposed to surely ? I thought only bulk metal types can be > > considered to be truly 'noiseless' like that. > > > LOL! > Resistors don't have shot noise. Shot noise comes from the electrons > getting through a potential barrier, which resistors haven't. > > You're probably confusing with excess noise, which shows as 1/F noise > and is proportional to the current flowing through the resistor since > it's basically resistor fluctuation. Yes. They sound similar though. Graham
From: John Larkin on 22 Mar 2007 21:50 On Thu, 22 Mar 2007 22:30:20 +0000, Eeyore <rabbitsfriendsandrelations(a)hotmail.com> wrote: > > >John Larkin wrote: > >> But metal film resistors don't have shot noise current. > >You mean they're not supposed to surely ? I thought only bulk metal types can be >considered to be truly 'noiseless' like that. > >Graham Vile Vishay propaganda. They publish some criminally silly nonsense. I tested an assortment of resistors for shot noise and couldn't see any, at least not as much as 20% of full shot statistics, which was about my noise floor. And that included the cheapest surface mount and axial carbon film 5%'s I could find. Some day I want to do a more sensitive test, with a mess of low-noise jfets or something. I still think carbons may have some shotty behavior. John
From: Fred Bartoli on 23 Mar 2007 04:01 Eeyore a �crit : > > Fred Bartoli wrote: > >> Eeyore a �crit : >>> John Larkin wrote: >>> >>>> But metal film resistors don't have shot noise current. >>> You mean they're not supposed to surely ? I thought only bulk metal types can be >>> considered to be truly 'noiseless' like that. >> >> LOL! >> Resistors don't have shot noise. Shot noise comes from the electrons >> getting through a potential barrier, which resistors haven't. >> >> You're probably confusing with excess noise, which shows as 1/F noise >> and is proportional to the current flowing through the resistor since >> it's basically resistor fluctuation. > > Yes. They sound similar though. > > Graham > Not quite. Shot noise has a strict flat PSD and is proportional to current, while excess noise PSD is almost 1/F and is proportional to current^2. -- Thanks, Fred.
From: Ian on 23 Mar 2007 08:02 "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message news:n7c603p8dpud39oa9kgn5oocjfcb78khe1(a)4ax.com... > On Thu, 22 Mar 2007 22:30:20 +0000, Eeyore > <rabbitsfriendsandrelations(a)hotmail.com> wrote: > >> >> >>John Larkin wrote: >> <snip> > > I still think carbons may have some shotty > behavior. > > John > I thought you misspelt that for a minute... Regards Ian ;-)
From: John Larkin on 23 Mar 2007 12:34
On Fri, 23 Mar 2007 09:01:11 +0100, Fred Bartoli <fred._canxxxel_this_bartoli(a)RemoveThatAlso_free.fr_AndThisToo> wrote: >Eeyore a �crit : >> >> Fred Bartoli wrote: >> >>> Eeyore a �crit : >>>> John Larkin wrote: >>>> >>>>> But metal film resistors don't have shot noise current. >>>> You mean they're not supposed to surely ? I thought only bulk metal types can be >>>> considered to be truly 'noiseless' like that. >>> >>> LOL! >>> Resistors don't have shot noise. Shot noise comes from the electrons >>> getting through a potential barrier, which resistors haven't. >>> >>> You're probably confusing with excess noise, which shows as 1/F noise >>> and is proportional to the current flowing through the resistor since >>> it's basically resistor fluctuation. >> >> Yes. They sound similar though. >> >> Graham >> > >Not quite. >Shot noise has a strict flat PSD and is proportional to current, while >excess noise PSD is almost 1/F and is proportional to current^2. Do you mean noise power? Shot noise current is proportional to the square root of DC current. http://en.wikipedia.org/wiki/Shot_noise John |