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Two architectures of fully-planar differential-mode dual-band bandpass filters (DB-BPFs) with enlarged common-mode-suppression bandwidth are reported. The first one, which aims at designs with broadly-separated wide passbands, exploits the loading of extra lines in its balanced symmetry plane. Thus, multiple common-mode transmission zeros (TZs) are created to make wider the DB-BPF common-mode-rejection range. The second one can be used for realizations with closely-spaced passbands and employs a properly-balanced quasi-bandpass-type DB-BPF topology. In this case, the common-mode-mitigation bandwidth broadening is performed by adequately selecting the type of implementation for the short-circuit terminations of its resonating lines- i.e., virtual or physical short circuits in the differential-mode operation-. For experimental-validation purposes, two microstrip DB-BPF prototypes are manufactured and tested.
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Dynamically tuning and reconfiguring microwave bandpass filters using optical control of switching elements
Abstract We report a novel approach for dynamically tuning and reconfiguring microwave bandpass filters (BPFs) based on optically controlled switching elements using photoconductivity modulation in semiconductors. For a prototype demonstration, a BPF circuit featuring a second‐order design using two closely coupled split‐ring resonators embedded with multiple silicon chips (as switching elements) was designed, fabricated, and characterized. The silicon chips were optically linked to fiber‐coupled laser diodes (808 nm light) for switching/modulation, enabling dynamic tuning and reconfiguring of the BPF without any complex biasing circuits. By turning on and off the two laser diodes simultaneously, the BPF response can be dynamically reconfigured between bandpass and broadband suppression. Moreover, the attenuation level of the passband can be continuously adjusted (from 0.7 to 22 dB at the center frequency of 3.03 GHz) by varying the light intensity from 0 to 40 W/cm2. The tuning/reconfiguring 3‐dB bandwidth is estimated to be ~200 kHz. In addition, the potential and limitations of the proposed approach using photoconductivity modulation are discussed. With the strong tuning/reconfiguring capability demonstrated and the great potential for high‐frequency operation, this approach holds promise for the development of more advanced tunable filters and other adaptive circuits for next‐generation sensing, imaging, and communication systems.
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- Award ID(s):
- 2223949
- PAR ID:
- 10534885
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Microwave and Optical Technology Letters
- Volume:
- 66
- Issue:
- 2
- ISSN:
- 0895-2477
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/mop.34082
