** Just looked up who Frank Siefert is:
Frank has a doctorate in Physics from Leibniz University and is employed at
the Max Plank Institute for Gravitational Physics. His special area is
control of high powered lasers as used in gravitation wave detectors.
Mention of his 2009 thesis can be seen here.
http://www.aei.mpg.de/english/contemporaryIssues/publications/doctoral/index.html
..... Phil
Reply by Phil Allison●May 8, 20112011-05-08
"John Larkin"
>
> It would be an interesting project to measure various resistors for
> shot noise. I wish I had the time.
>
** Frank Seifert had the time and the inclination:
https://dcc.ligo.org/public/0002/T0900200/001/current_noise.pdf
Nice procedures and results in line with maker's data and my expectations.
Thick film resistors ( Cermet) are the poorest, then carbon comp, carbon
film, metal films and the bulk foil and wire wounds come out as top dogs.
The high powered resistors shown in the Fig 9 are all forms of Cermet in
TO220, TO246 and similar style packs.
.... Phil
Reply by John Larkin●May 7, 20112011-05-07
On Sat, 7 May 2011 10:53:58 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:
>On Thursday, December 23, 2010 4:30:26 AM UTC-8, Kevin Aylward wrote:
>> "John Larkin" wrote \
>> >>>>OK: LT Spice resistors seem to not have shot noise.
>
>> >Do poly resistors have shot noise? Semiconductor currents generally
>> >have full shot noise.
>>
>> Poly resisters are continuous sheet of poly. There is no junction/potential
>> barrier, so no shot noise. Technically there are the end contacts, but these
>> are heavily doped to make them ohmic by construction.
Suppose a conventional resistor (metal plates with highly resistive
element between) were squashed very thin and flat, so that electrons
crossing between plates were far away from others laterally, and
crossed quickly enough that they had little likelyhood of interacting
with nearby ones. Wouldn't that result in shot noise? Geometrically,
that would be like a semiconductor junction, large area but very thin,
so electrons cross but don't get much opportunity to correlate.
>
>But, isn't there recombination noise? The charge carriers can enter
>and leave the channel by recombination, just as by injection,
>and that DOES carry some shot noise. It'd depend on the
>geometry of the resistor, and the (?Debye) distance scale.
I found this:
http://www.math.tamu.edu/~berko/banff/talk-slides/banff08-macucci.pdf
It says that mechanisms like geometry and scattering impurities can
break up electron ordering and result in values around 1/3 full shot
noise. Some geometries have Fano factors closer to 1.
As a practical matter, probably any resistor cruddy enough to have
shot noise would have unacceptable amounts of 1/f noise.
John
Reply by whit3rd●May 7, 20112011-05-07
On Thursday, December 23, 2010 4:30:26 AM UTC-8, Kevin Aylward wrote:
> "John Larkin" wrote \
> >>>>OK: LT Spice resistors seem to not have shot noise.
> >Do poly resistors have shot noise? Semiconductor currents generally
> >have full shot noise.
>
> Poly resisters are continuous sheet of poly. There is no junction/potential
> barrier, so no shot noise. Technically there are the end contacts, but these
> are heavily doped to make them ohmic by construction.
But, isn't there recombination noise? The charge carriers can enter
and leave the channel by recombination, just as by injection,
and that DOES carry some shot noise. It'd depend on the
geometry of the resistor, and the (?Debye) distance scale.
Reply by John Larkin●May 7, 20112011-05-07
On Sat, 7 May 2011 23:22:37 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:
>
>"John Larkin"
>>
>> There's not much available in the books I have, or online, about shot
>> noise, other than that tubes and semiconductors have it, and metallic
>> resistors don't.
>
>** Only pure metal resistors are free of excess noise - wire wound and "
>metal foil " types are two examples.
>
>Metal film ( sputtered metal ) resistors are not so blessed having excess
>noise typically quoted as in the order of 0.1uV/V/decade of frequency - as
>verified by my tests a couple of years back and posted here.
>
>Even Wiki has a neat summary of the basic facts:
>
>http://en.wikipedia.org/wiki/Resistor#Electrical_and_thermal_noise
>
>
>
>
>.... Phil
>
>
I still haven't found a reference that says whether nonmetallic
resistors and ionic liquids have true (uncorrelated electron) shot
noise. Shot and 1/f and whatever are usually lumped as "excess noise."
Electrons do like to spread out evenly. Even a vacuum diode has
somewhat less than shot noise because of mutual electron repulsion.
We needed a 50M low-noise resistor, to make a small bias current in
about a 2 MHz system, and cermets were terible. We used two 25M Dale
axials in series, RN55 types, probably vacuum coated films on ceramic
tubes, and they appered to have no excess noise. The rest of the board
was all surface mount, so we flew them over other parts, with a
mid-air solder joint.
It would be an interesting project to measure various resistors for
shot noise. I wish I had the time.
John
Reply by TheGlimmerMan●May 7, 20112011-05-07
On Sat, 07 May 2011 10:35:16 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
>Phil Allison wrote:
>> "John Larkin"
>>>
>>> There's not much available in the books I have, or online, about shot
>>> noise, other than that tubes and semiconductors have it, and metallic
>>> resistors don't.
>>
>> ** Only pure metal resistors are free of excess noise - wire wound and "
>> metal foil " types are two examples.
>>
>> Metal film ( sputtered metal ) resistors are not so blessed having excess
>> noise typically quoted as in the order of 0.1uV/V/decade of frequency - as
>> verified by my tests a couple of years back and posted here.
>>
>> Even Wiki has a neat summary of the basic facts:
>>
>> http://en.wikipedia.org/wiki/Resistor#Electrical_and_thermal_noise
>>
>>
>>
>>
>> .... Phil
>>
>>
>>
>
>Excess noise (aka flicker noise and 1/f noise) is a different issue from
>shot noise. Flicker noise is caused by conductance fluctuations, and is
>concentrated at low frequency, whereas shot noise is caused by
>decorrelation of the electrons and is white.
>
>(IIRC you pointed that out in one of our recurrent discussions of this
>topic.)
>
>Cheers
>
>Phil Hobbs
You forgot to describe one over f.
Reply by Phil Hobbs●May 7, 20112011-05-07
Phil Allison wrote:
> "John Larkin"
>>
>> There's not much available in the books I have, or online, about shot
>> noise, other than that tubes and semiconductors have it, and metallic
>> resistors don't.
>
> ** Only pure metal resistors are free of excess noise - wire wound and "
> metal foil " types are two examples.
>
> Metal film ( sputtered metal ) resistors are not so blessed having excess
> noise typically quoted as in the order of 0.1uV/V/decade of frequency - as
> verified by my tests a couple of years back and posted here.
>
> Even Wiki has a neat summary of the basic facts:
>
> http://en.wikipedia.org/wiki/Resistor#Electrical_and_thermal_noise
>
>
>
>
> .... Phil
>
>
>
Excess noise (aka flicker noise and 1/f noise) is a different issue from
shot noise. Flicker noise is caused by conductance fluctuations, and is
concentrated at low frequency, whereas shot noise is caused by
decorrelation of the electrons and is white.
(IIRC you pointed that out in one of our recurrent discussions of this
topic.)
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net
Reply by Phil Allison●May 7, 20112011-05-07
"John Larkin"
>
> There's not much available in the books I have, or online, about shot
> noise, other than that tubes and semiconductors have it, and metallic
> resistors don't.
** Only pure metal resistors are free of excess noise - wire wound and "
metal foil " types are two examples.
Metal film ( sputtered metal ) resistors are not so blessed having excess
noise typically quoted as in the order of 0.1uV/V/decade of frequency - as
verified by my tests a couple of years back and posted here.
Even Wiki has a neat summary of the basic facts:
http://en.wikipedia.org/wiki/Resistor#Electrical_and_thermal_noise
.... Phil
Reply by John Larkin●May 6, 20112011-05-06
On Fri, 06 May 2011 12:59:45 +0200, Uwe Hercksen
<hercksen@mew.uni-erlangen.de> wrote:
>
>
>John Larkin schrieb:
>
>> Shot noise is the random arrival of electrons, Poisson statistics. One
>> amp is one amp, no matter how it's generated. If the electrons are
>> uncorrelated, you have full shot noise. Metals are remarkable because
>> physical phenomena correlate the electrons, at least if the conductor
>> is long enough.
>
>Hello,
>
>if 1 amp is flowing 1 second long, 6,241,509,629,152,650,000 electrons
>are passing. It is hard to detect shot noise under this condition, but
>this is no proof that it does not exist.
Yup. Full shot noise at 1 amp is 5.66e-10 amps RMS.
If we think about 1 nA flowing
>1 �s long, we have only 6,241 electrons passing, but it may be 6,242
>electrons also. With current less than 1 nA, shot noise is detectable.
It's approaching 0.1% in a KHz bandwidth.
>
>Bye
A photodiode pulse of, say, 100 nA has obvious shot noise as seen on
an oscilloscope.
We measured a bunch of 50 meg resistors for excess noise. The cermets
were very noisy compared to metal films. It's a tricky measurement but
not impossible. The spectrum suggested that a lot of the noise was
shot noise, but it's hard to keep the bandwidth up at the impedances
involved.
I conjecture that some very cruddy materials, like cermets and ionic
liquids, don't have the long-term ordering that fixes shot noise in
metals.
There's not much available in the books I have, or online, about shot
noise, other than that tubes and semiconductors have it, and metallic
resistors don't.
John