Noise in resistor interesting article

[Overspeed]

Hello

An interesting article on noise in resistors

Regards
OS

[tggzzz]

Hello

An interesting article on noise in resistors

Regards
OS

Characterization of low-frequency noise sources
in planar devices using cross-shaped 4-terminal

Vincent Mosser and Alexandre Kerlain
Itron France, 50 avenue Jean Jaures, F-92120 Montrouge
vincent.mosser@itron.com, +33 146 00 66 74

Abstract. We promote here the use of cross-shaped 4-terminal devices (Hall crosses) to measure
LF noise spectra in planar technologies. The implementation of this method is described. When
investigating LF noise for the purpose of material or process characterization, such a procedure
is more simple and straightforward compared to conventional differential noise measurements
based on a Wheatstone bridge or single-ended measurements based on proprietary electronic
circuitry. As an example of application, we then use it to extract information on the energetic as
well as spatial location of a trap in Metal-Insulator-Semiconductor PHEMT pseudomorphic
heterostructures.
Keywords: GaAs, LF-noise, P-HEMT, LF-Noise measurement set-up.

[Overspeed]

@TGGZZZ

Hello

Thanks , I have this french article . I am in process to machine some maganin parts do test cross shape geometry.
 I will post a report asap I have solved my reference resistor question / concern

Regards
OS

[Kleinstein]

The cross shape may be useful for relatively noise parts with relatively high resistance. A downside of the cross shape is that there is quite some resistance outside the active zone and thus more heat problems.

With a manganin resistor one usually gets very low excess noise, up to the point that is can get tricky to see it all. It makes sense to have a shape to minimize the avoidable heat. A more conventional bridge arangement (could still be from 1 part) may be better suited.
Chances are one would have to use an AC excitation and measurement to avoid 1/f noise from the test setup.

A hall effect like probe would also be sensitive to actual hall effect and fluctuations in the magnetic field.

[Overspeed]

Hello

Regarding heat as I use low current levels and maganin resistor are nor very small I have a chance to limit the ''bad side '' , but I will run a monitoring of the temperature inside the housing

up to right now I have used DC , current generated by a voltage ref IC + OpAmp + resistor as in the video of eevblog on YT

I have started circuit as described in the linked PDF but JFET are costly and hard to find

I dont want to invest in a Keithley 2600

I plan :
to use an AC square current
to use frequency over 50 Hz

But I need to work on the MOSFET circuit I have just received my first PCB from PCBWAY

right now I use two 4 wires Isabellenhutte 0.001 Ohm components in parallel with a home PCB built with copper foil on a FR4 plate 

Advantage of cross maganin metal parts will the nois and the possible connection each other

Regards
OS

[Kleinstein]

The excess noise level from a manganin resistor is expected to be very small and proportional to the drive voltage. I would expect a noise index of better than -60 dbi  , at least when not nusing a very small one. That would be something like  < 1 nV  (for 1 decade, like 0.1 - 1 Hz) when using 1 V as excitation.  Unless the resistor is dirven rather hard, it would be difficult to see anything. As manganin resistors are usually low ohms (e.g. < 100 ohm) heat will be a problem and a low drive amplitude is not really an option.  I would aim for AC drive (likely sine to avoid EMI problems) with a few 100 Hz and lock in type detection, likely with a transformer to get a good noise ( << 1 nV /sqrt(hz)) with the low resistance.

I would still aim for a bit higher resistance, maybe 1 ohm or so from a thin (e.g. 0.1 mm) maganin wire.

For testing the concept with excess noise, I would first do a test with some much more noisy (but still low TC) resistors. Something like NOMCA or AORN resistor arrays or low TC thinck fim resistors of some 1-10 K would be a relatively easy target.