Compact dual-/tri-/quad-band bandpass filters with independently frequency-tunable and switchable passbands

Abstract

This paper presents the design of frequency-tunable dual-band, tri-band and quad-band bandpass filters (BPFs). The proposed three BPFs can be independently tuned and individually switched by varying the capacitances of the varactors. In the designed tunable dual-band BPF (TD-BPF), common input/output feed lines are utilized for two tunable dual-mode resonators (TDRs). Further, three TDRs and four TDRs are employed to achieve tunable tri-band BPF (TT-BPF) and tunable quad-band BPF (TQ-BPF), respectively. Then, the TD-BPF and the TT-BPF are fabricated and measured to verify individual tunability and independent switchability. For the TD-BPF, the measurement results show that the center frequency (CF) of the first passband varies from 1.37 to 1.62 GHz, and the CF of the second passband varies from 2.3 to 2.64 GHz. In the measured TT-BPF, the tuning ranges of CFs of three passbands are 1.3–1.5 GHz, 2.36–2.6 GHz, and 3–3.54 GHz, respectively.

Multi-Band Bandpass Filter Using Novel Topology for Next-Generation IoT Wireless Systems

“…Nowadays, researchers are more focused on developing miniaturized quad-, penta-, and sext-band BPFs. Different design topologies have been adopted to develop quad-band BPF [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. A popular method to design a quad-band BPF is by using stub-loaded topology [9][10][11][12][13].…”

A Miniaturized Reconfigurable Quad-Band Bandpass Filter With W-Shaped Sirs

“…Multi-band bandpass filters (BPFs), which are key components of wireless systems, have become increasingly important with the rapid growth of multi-service wireless communication networks [1]. Many different BPFs with different operation bands have been proposed in recent years to achieve this goal [2][3][4][5][6]. Various techniques, such as loading distributed capacitors in the inner area of conventional dual-mode loop resonators [7], employing meander-loop resonators [8,9], open loop resonators, and hybrid loading different resonators, can be used to produce dual-band operations.…”