A Miniaturized Low-Loss Switchable Single- and Dual-Band Bandpass Filter

In this paper, a novel switchable bandpass filter is proposed. By switching p-i-n diodes on/off, the proposed filter can be switched between the single-band bandpass filter and the dual-band bandpass filter. The filter is mainly composed of eight pairs of series LC resonators, which generate passbands and transmission zeros. Considering the requirement of miniaturization and low cost, the filter is realized by interdigital capacitors and microstrip section inductors. The layout is designed by 3D simulation software HFSS, and the active part is designed by ADS software. The proposed filter has a compact structure, and its size is only 22.20 mmx25.66 mm. For a demonstration, a switchable bandpass filter has been designed, fabricated, and measured. The simulated and measured results have a good agreement.