3.1 Introduction: The Current Conveyor Concept

A current conveyor is a four (possibly five) terminal device which when arranged with other electronic elements in specific circuit configurations can perform many useful analog signal processing functions ^[1 ^, 2 ^, 3 ^]. In many ways the current conveyor simplifies circuit design in much the same manner as the conventional operational amplifier (op-amp). This stems largely from the fact that the current conveyor offers an alternative way of abstracting complex circuit functions, thus aiding in the creation of new and useful implementations. This together with the fact that the actual terminal behavior of the current conveyor, like the op-amp, approaches its ideal behavior quite closely. This, as most designers of op-amp circuits know, implies that one can design current conveyor circuits that work at levels that are quite close to their predicted theoretical performance. Hence, once the functionality of the current conveyor is understood, the reader should be able to design complex analog circuits using current conveyors rather easily.

At the time of the introduction of the current conveyor (1968) it wasn't clear what advantages the current conveyor offered over the conventional op-amp. Moreover, the electronics industry was just beginning to focus its efforts on the creation and application of the first generation of monolithic op-amps. Without clearly stated advantages, the electronics industry lacked the motivation to develop a monolithic current-conveyor realization. After all, the op-amp concept was entrenched in the...