Topological emulation of continuous-time passive prototypes using wave port adaptors

A novel systematic method for designing high-order wave active filters is proposed in this study. This is based on an appropriate description of both the behaviour of passive elements and the topology of the prototype filter using the wave variables. The fulfillment of the Kirchhoff´s laws is achieved by employing wave port adaptors. The proposed realisation of the topological emulation of prototype filter is performed using current-mirrors as active elements. This is originated from the fact that summation/subtraction and scaling operations are required for the realisation of wave port adaptors. An attractive characteristic of the proposed method is that the derivation of high-order filters is a one-step procedure because of the availability of the wave active equivalents of passive elements and adaptors. A third-order elliptic filter has been designed in AMS 0.35 μm CMOS process and its performance has been evaluated and compared through simulation results.