A compact size switched reconfigurable tri-band BPF for modern wireless applications

This paper presents a novel reconfigurable triband BPF with two-state frequency responses, where tri-band and dual-band bandpass characteristics can be conveniently switched by turning pin diodes on and off. The filter can operate as a tri-band BPF with center frequencies 900 MHz, 2.45 GHz and 3.5 GHz for GSM and WiMAX applications. On the other hand, it can operate only at 2.45 GHz and 3.5 GHz for (WiMAX) rejecting 900 MHz GSM signals. The design proposes simple resonance microstrip structures integrable with pin diodes. Bias circuits are designed and optimized with precisely selected practical lumped components. The proposed filter is simulated, optimized, and fabricated using low loss Teflon substrate. The filter provides significant size reduction and superior enhancement in insertion losses.