I found in the noise simulation that the noise spectral density of many operational amplifiers including OPA211 is not flat after it is greater than 1M. I want to know whether this is a problem with the model or the real situation. Looking forward to your reply, thank you!
There must be something wrong with this model, because the white noise area is also much larger than the manual. But I still see the same phenomenon in other op amp models like OPA1611.
Hi Yue,
I assume you intended to simulate the OPAx211 which is a different device than the legacy/discontinued OPA2111. These are different devices.
The model the first post is for the legacy OPA2111, which also has an old style legacy model architecture/topology.
Below is a TINA noise simulation using the latest OPAx211 available on ti.com. The noise density remains near constant at around ~1.22nV/sqrt(Hz) to 1.44nV/Sqrt(Hz) as you move to higher frequencies to the gain bandwidth of the op-amp. When performing TI op-amp TINA simulations, please ensure to download the model directly from TI.com:
Also, on the plot, I modified the Y-axis into the logarithmic scale to match the plot of the datasheet.
Thank you and Regards,
Luis
OPAx211 TINA Noise simulation file:
HI Yue,
The TINA model from the OPA1611 product landing page, also shows the correct spectral noise density:
Thank you and Regards,
Luis
