On the SPRification of Linear Descriptor Systems via Output Feedback

We consider input-output systems in descriptor form and ask when such systems can be rendered strictly positive real (SPR) via output feedback. Time- and frequency-domain conditions are given to determine when and how this is possible. In addition, a synthesis procedure for controller design is also derived. Together, the results provide a complete answer to when a linear descriptor system can be made SPR via output feedback, and provide a recipe for design of a feedback controller when one exists.