Low-Voltage, Low-Power CMOS Current Conveyors

CCII block is powerful and simple at the same time, but the wide spread of possible applications has led to the development of evolutions and improvements of the basic CCII topology.
The simplest modification of the basic CCII topology is represented by its dual output version. As shown in the first chapter of this book, we usually distinguish between positive (CCII+) and negative (CCII-) implementations, depending on the I Z current sign with respect to the I X one, assuming the block itself as reference (see figure 4.1).
Current conveyors are often employed in applications that require a feedback between input and output terminals. In some applications, it can be useful to have both output currents inverted and non-inverted available. For this reason a dual output CCII, whose block scheme is shown in figure 4.2, can be implemented.
In the previous chapter, several solutions for current conveyor implementation have been presented. A dual output version of a given CCII is easily obtained simply adding some current mirrors at the output node. In this sense, starting, for example, from the circuit shown in figure 2.19, the corresponding dual output version of Z terminal is presented in figure 4.3.
A particular attention in current mirror design has to be paid if better performance of the improved CCII are...