Bandpass filter design with active inductor by means of wave digital approach

We present a wave digital approach (WDA) for the design of active filters based on high-Q active inductors (AI). The first approach proposed in the paper makes use of scattering parameters of the AI and has been conceived for RF practical applications. The use of active inductors in place of spiral inductors significantly improves the overall performance of the filter and allows to enhance both shape and quality factor with respect to a traditional passive configuration. With the proposed method is possible to take into account these improvements already at the design stage, so allowing to define the better topology and filter order. As an example of application, the filter has been optimised for operating at 2250 MHz with a 3 dB bandwidth of 30 MHz and a very high slope factor.