A note on stabilization by dynamic high gain output feedback

In this note we study the problem of stabilization by dynamic output feedback. For a certain class of linear systems we establish the existence of pairs of subspaces(Im, upsilon_{a}), whereImis a minimum phase input subspace contained in an almost stabilizability snbspaceupsilon_{a}. By applying a recent theorem by Sehumacber, this result leads to the existence of stabilizing high gain compensators for the linear systems under consideration. In particular, it will be shown that invertible minimum phase systems can always be stabilized by dynamic compensators of dynamic order equal to the excess of poles over zeros minus the number of inputs