  We solve the problem of output feedback stabilization of a class of nonlinear
systems, which may have unstable zero dynamics. We allow for any globally
stabilizing full state feedback control scheme to be used as long as it
satisfies a particular ISS condition. We show semi-global stability of the
origin of the closed-loop system and also the recovery of the performance of an
auxiliary system using a full-order observer. This observer is based on the use
of an extended high-gain observer to provide estimates of the output and its
derivatives plus a signal used by an extended Kalman filter to provide
estimates of the remaining states. Finally, we provide a simulation example
that illustrates the design procedure.
