A unifying framework for the circle criterion and other quadratic stability criteria

摘要

We present a result on the existence of a common quadratic Lyapunov function for a pair of linear timeinvariant systems. We show that this result characterises, generalises, and provides new perspectives on several well-known stability results. In particular, new time-domain formulations of the Circle Criterion and Meyer's extension of the KYP lemma are presented.