Frequency Tunable Non-Reciprocal Bandpass Filter Using Time-Modulated Microstrip λg/2 Resonators

This brief presents a novel frequency reconfigurable microstrip non-reciprocal bandpass filter based on time-modulated microstrip λ g /2 resonators. The modulation is achieved by loading both ends of the λ g /2 transmission line resonators with time-modulated capacitors. The modulation voltage sourc...

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Bibliographic Details
Published in:IEEE transactions on circuits and systems. II, Express briefs Express briefs, 2021-02, Vol.68 (2), p.667-671
Main Authors: Wu, Xiaohu, Nafe, Mahmoud, Melcon, Alejandro Alvarez, Gomez-Diaz, Juan Sebastian, Liu, Xiaoguang
Format: Article
Language:English
Subjects:
Band-pass filters
Bandpass filter (BPF)
Bandpass filters
Bandwidths
Electric potential
Frequency modulation
Frequency ranges
Insertion loss
isolator
magnetless
Microstrip
Modulation
non-reciprocal
Radio frequency
Resonant frequency
Resonators
time-invariant
time-modulated
Transmission lines
tunable
Tuning
Voltage
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Summary:This brief presents a novel frequency reconfigurable microstrip non-reciprocal bandpass filter based on time-modulated microstrip λ g /2 resonators. The modulation is achieved by loading both ends of the λ g /2 transmission line resonators with time-modulated capacitors. The modulation voltage source is connected at the center of the resonator, where there is a natural voltage null, and a single inductor is used to further enhance the biasing isolation. The wideband nature of this isolation scheme enables the tuning of the devices over a wide frequency range. With more than 30-dB RF to modulation isolation, the proposed resonator structure also enables low insertion loss by eliminating RF signal leakage to the modulation ports. A 3-pole bandpass filter example is simulated and measured, showing a minimal insertion loss of 3.9dB, a 20-dB isolation bandwidth of 42 MHz at 1.0GHz, and frequency tuning range of 885-1031 MHz.
ISSN:1549-7747
1558-3791
DOI:10.1109/TCSII.2020.3014499