Synthesis of Extracted-Zero Filters

We present an exact synthesis procedure for the low-pass prototype of extracted-zero filters. This type of filter has been recently introduced and it allows the realization of a true inline topology with up to two transmission zeros. Compared to other inline (or quasi-inline) solutions, the one here considered is the simplest to dimension and fabricate (the same techniques used for all-pole filters can be adopted). The procedure here presented has been applied to the synthesis of various prototypes and the results confirm the effectiveness of the proposed concept. A filter previously realized in a quasi-inline configuration has been re-designed in the new topology and the results obtained with the two topologies are compared and discussed.