Introduction of a pseudo-6th ISDN splitter with bandstop topology

A newly developed `integrated services digital network´ (ISDN) splitter with bandstop (BS) topology is presented and compared to an actual ISDN splitter with a traditional low-pass (LP) topology. The LP-to-BS topology change reduced the amount of filter stages: a LP ISDN splitter requires an 8<sup>th</sup> order elliptic-like filter in order to be compliant to the standard `TS 101 952-1-4 V1.1.1´ [1] of the European Telecommunications Standards Institute (ETSI), whereas the BS ISDN splitter only needs a pseudo-6^th order elliptic-like filter. The design of the new BS ISDN filter is discussed in the light of the enforced ETSI specifications. Furthermore, both the ISDN splitters are compared in the field of their specific stopband performance and their physical implementation. The area reduction that comes together with the introduction of the new ISDN splitter with BS topology is more than 25%.