TLV9001: Offset voltage

Hello Rui,

There is indeed an explanation for this.

You will see this occur with some rail-to-rail input op amps.  What happens is that if you have an input stage that is purely NMOS or purely PMOS, then you will not be able to take the input all the way from one rail to the other due to the input voltage needed to keep the input in its proper operating range.  To allow for full rail-to-rail operation, some amplifiers correct for this by having two input stages: one NMOS and one PMOS.  Depending on the input voltage, one will be on and the other will be off.

The benefit is that you get the full input range.  The downside to this topology is that when you cross the common mode voltage region that turns off one stage and turns on the other, the offset voltage will change.  We call this "crossover distortion." 

If this is an issue, you can make sure your common-mode voltage does not pass through the transition region or choose a rail-to-rail amplifier without this topology.

To learn more about crossover distortion, you can see our TI Precision Labs video on the subject.  Please let me know if you have any follow up questions.

Regards,

Daniel

Hi Rui,

see also section 8.3.2 of datasheet.

Kai