OPA27: Why the improved filter make the circuit stable

Hi user4090349,

user4090349 said:

Could you give some explanation of that? How R2 and C2 assure the stability of the circuit? Why R2*C2 = 2*R1*C1?

Op amp is not suited to drive capacitive load, especially larger capacitive load without proper compensation due to poor phase margin. The circuit below refers to dual feedback compensation, and I am unable to explain this in a few paragraph. 

The answer to you questions are summarized in the table below. 

https://www.ti.com/lit/an/sboa602/sboa602.pdf?ts=1740155848211&ref_url=https%253A%252F%252Fwww.google.com%252F

There is a version of Chinese translation over the TI website, but it is translated poorly and it is translated by I. I have tried to correct the mistakes in the Chinese version, but I do not believe that it has been revised. Anyway, you can read about it and it should answer 95% of your questions. The 0.5 refers to 1 octave or 2X (theoretical guideline). In actual practice, it should be close to 4X or 2 octaves, which I explained in the application note. 

If you have other questions, I will be happy to answer it for you. I am going to close the query for now. 

Best,

Raymond