Lumped-element RF analog multi-band bandpass filter concept for software-defined-radio architectures

Future software-defined radios (SDRs) for modern wireless applications—e.g., 5G communications—could require reconfigurable RF analog circuits to enable multistandard/service operation with hardware miniaturization. In this context, a lumped-element multi-band bandpass filter concept is presented. This filter architecture consists of the in-series cascade of several multi-transmission-zero-(TZ)-generation cells that are shaped by a plurality of series-type resonant branches. It allows to synthesize multi-band transfer functions with arbitrary order and number of passbands with inter-band TZs. A theoretical analysis of the proposed multi-passband filter scheme is expounded. Also, its potential for fully-reconfigurable multi-band bandpass filter realization through TZ reallocation is studied at the ideal-design level.