OPA211-HT: Parameter Testing of OPA211

Hi Nader,

Can you share where you are seeing this circuit. I am not too familiar with this, but I am not sure how Vos from the 2nd amplifier would not be a factor in the value seen at the output.

Best Regards,

Ignacio

I saw that in Precision labs series: Op amps | TI.com., Vos & Ib specifications video 

Hi Nader,

Yes, the output does take into account vos and ib error due to the 2nd amplifier as well. There is a section in the video that breaks down the math, it is taken into account by the fact that they multiply vos and ib error by the gain of both stages.

Best Regards,

Ignacio

Hi Ignacio,

Thanks for the support. I checked the calcs again and I don't see that VOS and IB of both op amps are taken into account. The correct cal should be:

Error Due to OP Amp1: (VOS+VIB)*G1*G2 

Error Due to OP Amp2: (VOS+VIB)*G2 

Total Error: (VOS+VIB)*G1*G2 + (VOS+VIB)*G2 

Please correct me if I am wrong. Thanks

Hi Ignacio,

I have another inquiry, more urgent one. 

I purchased OPA211SHJK and OPA2333SHJK. The ICs are embedded into white plastic frame. How do I carefully remove the ICs from the plastic frame ? Thanks

Hi Nader,

That is correct I am not sure if they are referring to the first stage only, but the output should have error due to the second stage as well. Your formulas are correct. Regarding your second question, I am not sure what exactly you're asking. Do you mean how to safely handle one of our devices? Or is the packaging itself difficult to open?

Best Regards,

Ignacio

Hi Ignacio,

Thanks very much for your response. 

1. Regarding testing VOS & IB, could you find out if the video formula is incorrect and if it is could you provide the correct formula ? Thanks

2. For my second issue, I have attached (below) a snapshot of the plastic "holder", which holds the IC. I am not sure how I remove the IC from the "holder". Could you provide separation/removal instructions ? Thanks

Hi Nader,

The equations you are using are correct. Regarding your second question, you should be able to just pop out the IC by pressing onto the case as there is a plastic piece that will pop out that is holding the device in place.

Best Regards,

Ignacio