difference between current conveyors

[azerty1]

Hello everyone,
I work on current conveyors and I found that there is three generations. what you can tell me about the difference between these three generations and the advantage of one over the others?
thank you

 

[LvW]

The classical second generation conveyor CCII has one high-resistive input , one low-resistive input (x) and one high-resistive output (z).
The first generation device CCI has two low-resistive inputs. And I do not know any practical application of this active unit.

I am not sure, but I suppose that the third generation CC has two output nodes. Thus, the versatility of the CCII (with a large range of applications) is even increased due to the second output (with reversed sign).