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Description
The study emphasizes a switchable characteristic of narrow-band coupled resonators of a dual-band filter developed based on the reactance transformation method as a single filter structure. The filter is realized on Mercurywave 9350 multi-layer substrate. The substrate was chosen for various reasons, including its relatively constant permittivity over frequency. The designs feature a dual-path topology connected in parallel, known as transversal topology. In this topology, modifying any of the resonators negatively impact the filter's response across both frequency bands. The total number of resonators employed (eight for the dual-band filter) makes the modification of individual resonators practically unviable. As a result, a basic non-resonant transmission line pre-selection approach is employed to select the desired passband, thus preventing frequency response deterioration in the selected band while eliminating the unwanted band. This approach involves integrating a pre-selection circuit with a dual-band filter to enable band switching. The switchable filter operates between two frequency bands: 3.1 GHz to 3.3 GHz and 3.6 GHz to 3.8 GHz. The non-resonant pre-selection circuit was integrated on a Mercury wave substrate in the uppermost layer and comprises four Skyworks PIN diodes (SMP1345-079LF) for switching purposes. Through the reversed and forward biasing of the diodes, the non-resonant pre-selection circuit eliminates one band while selecting another (selects one passband at a time).
Keywords – Switchable filters, coupled resonators, reactance transform, dual band
| Stream | Science or Engineering |
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