Microvolt power supply

[Paul98]

I hope it's the right section.I need to generate a stabilized voltage of +100uV. Is it feasible to get it with any voltage regulator that provides 1.25 or more volts and lower the voltage with a drop resistor in series or voltage divider without knowing the drain? The purpose of this circuit is to test micro-signal amplification devices. The length of wiring is short and i think is needed few mA of current. Thanks.

 

[KlausST]

Hi,

What accuracy/precision do you need?
Fixed output voltage or adjustable? (what range and resolution?)
You need to give at least an idea of load current range or load resistance range.

Klaus

 

[FvM]

Consider a buffer amplifier built with a "zero offset" OP.

Calculating the voltage drop of a passive divider is however easy.

 

[danadakk]

Consider noise when designing divider, and resistor type -

https://eepower.com/resistor-guide/resistor-fundamentals/resistor-noise/#

Johnson–Nyquist noise - Wikipedia

en.wikipedia.org

Thermal noise of resistor – Calculator | Audio Perfection

www.audio-perfection.com

Use a low noise Vref as well.


Regards, Dana.

 

[Paul98]

@KlausST
100uV +/-10% may be enough . Once set it will be fixed but only so as not to complicate the circuit.

@FvM
Did you mean with negative Gain? Never tried but i think is feasible.

@danadakk
I would prefer to use THT resistors as they are easier to remove in case of replacement. I also know that the material produces noise. I wonder if an SMD resistor can make more noise than a wire wound THT resistor.

 

[KlausST]

Hi,

100uV +/-10% may be enough

Is the +/- 10% the expected accuracy, the expected precision, or the adjustment range?
But without current ... it´s meaningless anyways.

Klaus

 

[danadakk]

@KlausST
100uV +/-10% may be enough . Once set it will be fixed but only so as not to complicate the circuit.

@FvM
Did you mean with negative Gain? Never tried but i think is feasible.

@danadakk
I would prefer to use THT resistors as they are easier to remove in case of replacement. I also know that the material produces noise. I wonder if an SMD resistor can make more noise than a wire wound THT resistor.

A good reference -

Current-Induced Resistor Noise

www.beis.de

Regards, Dana.

 

[Paul98]

@KlausST

Expected 100uV . It's also ok from 90uV to 110uV. Once the voltage closest to 100uV is obtained it will be fixed and permanent.

@danadakk

When we talk about micro signals I understand that it is therefore not recommended putting resistors in the signal line. At this point it is convenient to discard the idea of a resistor as a voltage drop on the signal. It seems the best solution is an op amp as suggested by @FvM or your Vref advice.

 

[KlausST]

It seems the best solution is an op amp as suggested by @FvM or your Vref advice.

Maybe, maybe not. It depends.

If the current is 1A, then a usual OPAMP can´t drive it. If it is 1nA then the OPAMP may cause more error than anything else....
Somewhere inbetween an OPAMP may make sense... one has to do error calculations...

Klaus