Does input offset voltage of opamp reverse polarity with temperature change?

Does input offset voltage of opamp reverses polarity with temprature change?

It's well known that input offset voltage of opamp changes with temprature. My question is, let us say we have +30uV offset voltage and let's assume noninverting input is higher than the inverting input. it's going to change with temprature with some spesific value. Can the polarity of the offset voltage change with temprature. To clarify with temprature change, can offset voltage be -30uV or some other negative voltage?

Re: Does input offset voltage of opamp reverses polarity with temprature change?

Offset is caused by an error in balance at the input due to small unavoidable manufacturing variations.

The initial error could go either way, positive or negative.
And there will be two errors, input voltage offset error and input bias current offset error.

Which predominates depends on the source resistance at the inputs.
If the input has a very low source resistance, bias current can be practically ignored, and the main problem then will only the voltage offset.

If the input resistance is unusually high, differences and changes in bias current will predominate, and dwarf any initial voltage offset.

Voltage offset change with temperature is usually much less than the change in input bias current with temperature, and both can go either way.

Things to consider are input resistance, and the op amp process (bipolar, jfet, mosfet).

If this all becomes too much, there are chopper stabilised amplifiers available that continually self correct for input offset.

Re: Does input offset voltage of opamp reverses polarity with temprature change?

I think that you cannot make a generate statement about whether the offset polarity can change with temperature.
My feeling is that it's not likely, but I have no concrete evidence to back that up.

Re: Does input offset voltage of opamp reverses polarity with temprature change?

Offset voltage temperature drift can of course change the offset polarity. It's likely to happen if the initial offset voltage is small (in the middle of the specified tolerance band).

Re: Does input offset voltage of opamp reverses polarity with temprature change?

Let us assume a device with a square law model.
Then the input offset voltage would depend both upon the mobility and threshold voltage.
So yes, there can be reversal.

Re: Does input offset voltage of opamp reverses polarity with temprature change?

Precision Amplifiers with Vos<= 10µV from Linear Technology all have ;
Temp coeff. <=+/- 1%*Vos(max)/°C

This type with higher Vos are worse in tempco. %*Vos(max)/'C

but always +/-.

Re: Does input offset voltage of opamp reverses polarity with temprature change?

"Can"? Sure. Especially in an amplifier that happens to
be close to its ideal Vio but within a wider spec window,
on competing defects these "features" can exhibit differing
tempcos individually and in sum.

Autozeroed amplifiers that use charge storage to null
the front end, can see drifts in the zeroing from drifts
in the switch timing and charge injection (the turnoff
tails, where the switch has cut out but the gate charge
still is looking for a way out, tend to be difficult to rein
in across all corners). An attempt is made to balance
and minimize charge injection but nothing ever succeeds
100.000000000000000000000000000000000000000000%.