LMP7731 is the input transistor NPN or PNP whichever?

Hello Masashi,

It has both...

It is a standard Rail-to-Rail bipolar input stage, so it has both NPN and PNP input pairs.

The NPN pair is on from V+ down to about 1V above V-, where it switches to the PNP pair to V-.

Regards,

Another clue is from an Input Bias Current vs. Common Mode Input Voltage graph.

When the NPN is active, as it will for positive (in respect to mid-supply) input voltage, the input bias current is positive.
When the PNP is active, as it will for negative (again, in respect to mid-supply) input voltage, the input bias current is negative.

Although, the LMP7731 seems to be opposite. Did someone flip a meter during characterization?

-Ken