Analysis and design of ltered-x adaptive algorithms are conventionally done by assuming that the transfer function in the secondary path is a discrete-time system. However, in real systems such as active noise control, the secondary path is a continuous-time system. Therefore, such a system should be analysed and designed as a hybrid system including discreteand continuous- time systems and AD/DA devices. In this article, we propose a hybrid design taking account of continuoustime behaviour of the secondary path via lifting (continuoustime polyphase decomposition) technique in sampled-data control theory.