Properties of zeros of discretised system using multirate input and hold

The paper investigates the proprieties of limiting zeros of a discrete-time system discretised by the use of multirate input and hold. The stability conditions of the limiting zeros for sufficiently small sampling periods are derived in the case that the relative degree of a continuous-time system is equal to two or three. It is also shown that the intersample behaviour arising from the multirate input can be localised by appropriately selecting the design parameters based on the stability condition of the zeros.