Co-designed quasi-reflectionless low-noise amplifier with bandpass filter and RF switching functionalities
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Date
2026-04-01
Authors
Cheng, Steven Matthew
Fontana, Andres
Psychogiou, Dimitra
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Abstract
In this letter, a reflectionless low-noise amplifier (LNA) filter (RLNAF) is presented, incorporating four distinct functions: 1) filtering; 2) reflection cancellation; 3) low-noise amplification; and 4) RF switching within a single component. It is comprised of a transmissive path and two absorptive paths. Specifically, a complex-termination methodology is applied to the transmissive path incorporating a bandpass filter (BPF) and LNA functionalities, removing the need for additional interstage matching networks (MNs). The absorptive paths are composed of a bandstop filter terminated with a loading resistor in one port to selectively dissipate the out-of-band reflected RF signals. Moreover, switch-off functionality is demonstrated by reconfiguring the bias of the transistor. For proof-of-concept validation purposes, two RLNAF prototypes are designed, manufactured, and measured at C-band. The RF characteristics are given as follows: RLNAF I: fcen=4.65 GHz, gain = 15.8 dB, noise figure (NF) = 2.07 dB, and quasi-reflectionless characteristics better than 10 dB from DC to 4.27 and 4.34 GHz to 6.42 GHz and at least 9.8 dB from 4.27 to 4.34 GHz; RLNAF II: fcen=3.7 GHz, gain = 15.3 dB, NF = 1.09 dB, and quasi-reflectionless characteristics better than 10 dB from DC to 4.75 and 5.75 GHz to 7.03 GHz and at least 6 dB from 4.75 to 5.75 GHz.
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© 2026, the Authors. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0
Keywords
Absorptive filter , Active filters , Band-pass filters , Circuits , Feeds , Filtering , Filters , Frequency modulation , Isolators , Notch filters , Radio broadcasting , bandpass filter (BPF) , Bandstop filter , low-noise amplifier (LNA) , Reflectionless filter , [EngineeringArchitecture] , [Tyndall]
Citation
Cheng, S M, Fontana, A & Psychogiou, D 2026, 'Co-designed quasi-reflectionless low-noise amplifier with bandpass filter and RF switching functionalities', IEEE Microwave and Wireless Technology Letters, pp. 1-4. https://doi.org/10.1109/LMWT.2026.3676313
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