Question about the gain-boosting method for OTA

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nathanee

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gain-boosting OTA

Hi, there,

In order to improve the gain of an OTA, the gain-boosting method is an useful thchnique.
what is the relationship between main OTA, and "A" shown in the figure?
Supposed that the UGB of main OTA is 200MHz, how about the opamp "A"?
Is any systematic calculation document?


 

gain-boosting OTA

Since you are only boosting at low frequencies, I do not see a reason to have gain at frequencies you do not want to boost.

So first design your main amp. Find the -3dB point of the open loop gain. Then make the boost amps with a UGBW slightly higher then that -3dB point.

This could cause a slow settling behavior though.
 

Re: gain-boosting OTA

the UGBW of A is near to the UGBW of main OTA, that is ok
 

Re: gain-boosting OTA

Read the material that ljy4468 provided. Be careful about the relationship of UGBW between booster and main amplifier, which may cause doublet.
 

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