Introduction of a pseudo-6th order 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 lowpass (LP) topology. The LP-to-BS topology change reduced the amount of filter stages: a LP ISDN splitter requires an 8th 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-6th 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%

Active-tunable inductor effected by a novel impedance synthesis

This paper describes a novel impedance synthesis (IS) circuit: the impedance of an inductor is made tunable as a function of the frequency by means of a transconductance function g(m)(s) that is located in the feedback loop. In order to show the potential of this novel IS circuit, the effect of several basic transconductance functions onto the synthesized impedance is presented. The specific case of g(m)(s) similar to s(-1) brings up the 'coil enhancement' feature of this IS circuit: the synthesized impedance is purely inductive with an actual boosted inductance level compared to the inductance of the physical inductor. Based upon this 'coil enhancement' property, the IS circuit is incorporated in new plain old telephone service' (POTS) low-pass filter which is fully compliant to the 'TS 101 952-1-1 V1.2.1' standard([1]) of the European Telecommunications Standards Institute (ETSI)

Development of the area-reducing active 'coil-enhancement' principle, practised onto an ADSL-POTS splitter

This paper describes the theory behind the "coil-enhancement" principle: The impedance of an inductor is made controllable as a function of the frequency by means of a transconductance function g(m) (s) that is located in the feedback loop. In order to show the potential of the coil-enhancement circuit, the effect of several basic transconductance functions onto the synthesized impedance is presented. The specific case of g(m) (s) similar to s(-1) produces the coil-enhancement situation and is discussed in detail. One drawback of the coil-enhancement circuit is found in the series resistance of a second inductor, also positioned in the feedback loop. The influence of this series resistance onto the synthesized impedance is addressed and a work-around is presented. A newly developed active "plain old telephone service" (POTS) splitter, based upon the coil-enhancement principle, is derived from a fully passive POTS splitter in which two large inductors are merged together into one active inductor. The active POTS splitter is fully tested and is found compliant with the standard "TS 101 952-1-1 V1.2.1 (option A)" of the European Telecommunications Standards Institute. The area reduction that comes together with the passive-to-active conversion is 40%