Instrumentation amplifier input offset

Hello Vasilis,

Regarding input offset voltage of TI operational and instrumentation amplifiers, you'll notice there are two values of interest in the datasheet - Typical and Maximum.

Typical values represent one standard deviation on a Gaussian distribution (or 67%), meaning that 67 out of every 100 devices will have an input offset at or below the Typical value, when tested using the conditions noted in the datasheet. Note that the Typical datasheet value represents the upper bound of this distribution, and that a majority of our devices will in actuality have a measured offset value that is very close to zero. Take for example the INA188 input offset distribution below; the Typical input offset voltage rating is 25 µV, but note the majority of the distribution is centered around 0 µV, meaning a majority of shipped devices will have close to zero input offset voltage. 

The other offset value of interest is the Maximum value. Maximum values are tested values, and every amplifier with a Maximum value is tested before leaving the factory to ensure the device specifications do not exceed the Maximum values; any tested device with an offset exceeding the Maximum value is disposed of. So again using the INA188 as an example, with a Maximum input offset value of 55 µV, there is no chance that any shipped units will ever have an offset that exceeds 55 µV - again, assuming the same testing conditions that are used to generate the datasheet values. 

So to answer your question, assuming you are referring to the Maximum input offset value of TI's instrumentation amplifiers, so long as you adhere to the same testing conditions outlined in the datasheet, shipped amplifiers will not exceed the Maximum datasheet value. 

Christopher Stemple

Product Marketing - Precision Amplifiers