LM324: Input offset current drift

Edward,

1. The offset current drift should have a +/- symbol in front of it.  Sorry for the oversight in the data sheet.  We should always state the polarity but sometimes it is overlooked.
2. You didn't explicitly ask this but here is an explanation of this devices bias current specifications:
   1. This circuit has PNP input transistors  without bias current cancelation.  This means that the bias current is always negative because the bias current is the base current for the transistors.
   2. The bias current offset is the mismatch in the input transistors.  This mismatch is not deterministic.  That is, you cannot predict which of the input transistors will have higher IB.  Thus, IOS positive or negative.  This is correctly identified in the data sheet.
   3. Since the direction of IOS can be positive or negative the drift can also go in either direction.  You cannot predict which of the two input transistors will have a higher IB at higher temperature.
3. In general IB and IOS will get worse at high temperatures.
4. Op Amp Offset Voltage and Bias Current Limitations covers IB and Vos in detail.  

Best regards, Art

Edward,

Yes, you are correct. 

Best regards, Art