On delay-dependent passivity

Sufficient conditions for passivity (positive realness) are obtained for continuous-time, linear, retarded, and neutral-type systems. A delay-dependent solution is given in terms of linear matrix inequalities (LMIs) by using a descriptor model transformation of the system and by applying Park's inequality for bounding cross terms. A memoryless state-feedback solution is derived. Numerical examples are given which illustrate the effectiveness of the new theory.