Passification of linear systems with respect to given output

The concepts related to passifiability (feedback passivity) of systems with the given output are introduced. They are intended to study passifiability of systems with respect to output y by output feedback based on output y₁ for the case when y₁ differs from y (extended passifiability). Necessary and sufficient conditions for extended passifiability of linear systems by linear output feedback are established. Links of the obtained results to the high gain stabilization are shown and an extension to passifiability with different inputs is given. The proofs are based on a version of the celebrated Yakubovich-Kalman-Popov lemma (KYP-lemma) and Meerov¿s results on high-gain stabilization.