Tunable semi-lumped dual response filter using active capacitor circuit for multistandard systems

This paper deals with the design of a novel tunable dual response active filter aiming to allow the coexistence in a single terminal of the respective standards, DVB-H for digital TV reception, WIMAX for internet connectivity and GSM for cellular telephony. The filter concept is based on the combination of an active low-pass filter and a semi-lumped tunable active notch filter. Both of two filters have been modified by adding for each network an active capacitor in order to improve their performances. Moreover, the tunability of the notch filter has been demonstrated while achieving a very high degree of miniaturization, thanks to the slow-wave behaviour introduced by capacitively loaded transmission line. The complete design has been fully simulated and experimental prototypes realized and measured, demonstrating the benefits of the proposed design.