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Precision op amps - is 1 microvolt offset believable?

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I saw it in a data sheet of an Analog Devices MOSFET-input precision op amp. Has anyone tried to use such an op amp, so you can tell me if
1 µV voltage offset is true?
 

1 uV offset, or even a bit lower, can be achieved with chopper stabilized amplifiers.
 

Yes, in a chopper or zero drift opamp. They use various switching architectures that can theoretically cancel all offset and drift. The switching comes with some downsides however - usually residual voltage and current noise. However they keep improving.

See Opa189 for a recently released example with impressive specs.
 

Hi,

For sure this is true.
But you need some schematic and PCB layout experience to achieve this with your application.

Klaus
 

Chopper amplifier of microvolt DC signals

I understand that a chopper keeps flipping the input DC signal so that an AC signal is obtained and amplified.
But to do it with microvolt signals requires using noise-free switches. The only relatively noise-free method of
switching that comes to my mind is using photoresistors and proper light sources. But I know that photoresistors
are slow - 10s of milliseconds.
So how is it done?
 

its an Analog Devices part
they've been making analog parts for a long time
you can believe the data sheets

follow the instructions in the data sheets and ap notes
talk the the applications engineers at Analog Devices
 

The only relatively noise-free method of switching
Click to expand...
that you know of ...

- - - Updated - - -

read the data sheet very carefully - you may learn something ...
 

Hi,

I understand that a chopper keeps flipping the input DC signal so that an AC signal is obtained and amplified.
But to do it with microvolt signals requires using noise-free switches.
Click to expand...
Don't mix different things:
* offset is DC
* noise is AC
Low offset doesn't mean low noise.The one has nothing to do with the other.

And generally chopper stabilized Opamps are more noisy than standard Opamps....especially the older ones.
In former this was a problem, but modern ones greatly improved in this.

Klaus
 
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