let's consider this logarithmic multi - stage amplifier:
Each stage is an amplifier with this mechanism: if the input signal is small (under a certain threshold), it is amplified with high gain A; if it is large (over the previous threshold), it is amplified with unitary gain.
The purpose of this multi - stage amplifier is that of getting a Voutput - Vinput curve like that in the previous picture. But I do not understand the presence of the Adder circuit. I think that simply the cascade of the previous amplifier will generate a curve like that, in which small signals are amplified a lot, and high signal are amplified less.
Can you help me on understanding the presence of the adder?
This circuit is analyzed here.