Nullor-Based Design of Compensators for Fast Transient Recovery of Switching Regulators

Compared to linear regulators, switching regulators are much slower in response to sudden load change. The dynamics are usually improved by introducing proper feedback loops whose design is based on frequency domain techniques and some appropriate models of the power stage. Fast transient recovery is generally difficult to achieve. In this paper, we present a new approach to designing compensators for achieving very fast transient recovery in switching regulators. Essentially, we create a “phantom" load for the switching regulator which, in the event of any rapid change of the actual load, remains as a slowly varying load. The design of such a phantom load is based on the use of two ideal elements, namely the nullator and the norator. Practical circuits can be easily constructed using active devices such as transistors and op-amps.