Current-mode realization of negative feedback SAB´s

The authors present a method of realizing the current-mode counterparts of the classical single amplifier biquad filters, especially those based on negative feedback. These filters are essentially combinations of a passive network with one or two finite-gain voltage controlled voltage sources. These sources can be inherently stable or not, depending on the op amp polarity. After the adjoint transformation has been applied, the voltage sources become current sources that in turn are inherently stable or not stable. These current sources can be practically implemented using a building block recently proposed by the authors. Practical examples and computer simulations are given to demonstrate the validity of the ideas. Even though the realization of the current-based active elements cannot be considered optimal, the resulting current-based filters exhibit an improved frequency response compared to their voltage-based counterparts