When reading this article, I couldn't understand the reason why CMRR is much higher in 3 op-amp topology:
In both above the resistor mismatch of the difference amplifier sections can be the same. What increases the CMRR in the second one. Can it be explained in simple terms?
In other words, how do the buffers which are added to the difference amplifier inputs have effects on the CMRR?
edit: According to this, the common mode voltage of A1 and A2 is buffered to A3, but what makes it reduced more? It is only subtracted at A3 as in differential amplifier. I dont get this. What increases the CMRR in the 3 amp model?