A Wideband Bandpass Filter with Broad Stopband and Ultra-Wide Reflectionless Range for 5G Applications

Liu, Changkun; Deng, Zhixian; Liu, Xiaohui

doi:10.1109/mwsym.2019.8700856

Cited by 21 publications

(7 citation statements)

References 6 publications

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“…For very high data rate transmission, the researchers also suggest the millimeter waves (mmWaves) as a vacant spectrum that can entirely be utilized for the 5G applications. However, the spectrum that is extended along the frequency band (2-8 GHz) is divided into a number of sub-bands to form the 5G 6 GHz sub-band (mid-band) communications, in order to be compatible with the already existing 4G devices [9,10]. The 6 GHz sub-bands used in the US are the (3.1-3.55 GHz) and (3.7-4.2 GHz) bands.…”

Section: Introductionmentioning

confidence: 99%

A Low-Cost Microwave Filter with Improved Passband and Stopband Characteristics Using Stub Loaded Multiple Mode Resonator for 5G Mid-Band Applications

et al. 2021

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This paper presents the design and implementation of a printed circuit microwave band-pass filter for 5G mid-band applications, using a Stub Loaded Multiple Mode Resonator (SL-MMR) technique. The objective of this article is to introduce a low-cost microstrip filter with improved passband and stopband characteristics, based on a mathematical analysis of stub loaded resonators. The filter cost is reduced by selecting the low-cost FR4 dielectric material as a substrate for the proposed filter. Based on the transmission line model of the filter, mathematical expressions are derived to predict the odd-mode and the even-mode resonant frequencies of the SL-MMR. The mathematical model also highlights the capability of controlling the position of the SL-MMR resonant frequencies, so that the 5G sub-band that extends along the range (3.7–4.2 GHz) can perfectly be covered with almost a flat passband. At the resonance frequency, a fractional bandwidth of 12.8% (500 MHz impedance bandwidth) has been obtained with a return loss of more than 18 dB and an insertion loss of less than 2.5 dB over the targeted bandwidth. Furthermore, a pair of parasitic elements is attached to the proposed filter to create an additional transmission zero in the lower stopband of the filter to enhance the suppression of the filter stopband. The measured and simulation results are well agreed, and both reveal the acceptable performance of the stopband and passband characteristics of the filter.

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Section: Introductionmentioning

confidence: 99%

A Low-Cost Microwave Filter with Improved Passband and Stopband Characteristics Using Stub Loaded Multiple Mode Resonator for 5G Mid-Band Applications

et al. 2021

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“…In Refs. 10–12, absorptive bandpass filters (ABPFs) based on a two‐branch structure is proposed. In addition, absorptive tunable BPFs were proposed in Refs.…”

Section: Introductionmentioning

confidence: 99%

“…13,14, which can be applied to reconfigurable RF front‐ends. However, the absorption performance is exhibited only at their input terminals 9–14 . In Ref.…”

Section: Introductionmentioning

confidence: 99%

An X‐band centrosymmetric microstrip bandpass filter with reflectionless range over 3.9–18.6 GHz and stopband up to 40 GHz

Zhang

Liu

2021

Micro & Optical Tech Letters

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In this letter, the design of a centrosymmetric absorptive bandpass filter (ABPF) with ultra‐wide reflectionless band at both input and output port and wide stopband is reported. It is based on a balanced‐circuit structure, consisting of a pair of 3‐dB couplers and two channels of conventional reflective bandpass filters (BPFs). The bandwidth of the 3‐dB couplers is maximized, which covers from C‐band up to beyond Ku‐band, to extend the reflectionless band of the ABPF. It is realized by introducing a cross‐fingered defected ground structure (DGS) into the classical coupled‐line coupler to strongly enhance the coupling effect while maintaining a compact size. To suppress the harmonics outside the passband, two C‐shaped DGSs are employed at the input and output ends of the coupled‐line‐based BPF which introduces extra transmission zeros in the stopband. A prototype of the proposed ABPF is fabricated and tested. Measured input/output return loss are better than 10 dB over 3.94–18.63 GHz, which is commonly viewed as the reflectionless band. Moreover, the upper stopband is extended up to 40 GHz with suppression higher than 23 dB. The presented ABPF features advantages in convenient integration, dual‐port ultra‐wide reflectionless band and broad stopband.

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“…and lumped-elements [26], split-type input-reflectionless multiband filters [27], filtering power dividers [28], dual-band microstrip BPF [29], and multiplexers [30], [31]. In [32], the main banpass channel, which consists of a bandpass filter and supur-lines, together with the bandstop auxiliary channel lead to a wideband bandpass filter with broad stopband and ultra-wideband reflectionless at the input port. Similarly, a wideband reflectionless filtering coupler is presented in [33] To achieve symmetrical two-port reflectionless properties using the complementary diplexer architecture, auxiliary absorptive circuits need to be loaded at both the input and output ports [22], [34].…”

Section: Introductionmentioning

confidence: 99%

Quasi-Reflectionless Microstrip Bandpass Filters With Improved Passband Flatness and Out-of-band Rejection

Wu¹,

Li²,

Liu³

2020

Preprint

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High-order quasi-reflectionless bandpass filters with improved passband flatness and good impedance matching both in-band and out-of-band are proposed in this work. The proposed design consists of conventional coupled-lines bandpass sections loaded with the presented absorptive stubs at the input and output. Analysis shows that the absorptive stub is equivalent to a 2-pole bandstop filter. Compared to the prior art, the higher-order nature of the presented absorptive stub enables a flatter passband and better out-of-band rejection. The overall filter stopband attenuation can be readily improved by increasing the number of coupled-lines sections without altering the passband responses. Furthermore, cross-coupling between the two absorptive stubs can be used to improve the out-of-band rejection by introducing two transmission zeros without affecting the absorption characteristics. The proposed design concepts are experimentally validated by the design and fabrication of a set of 2.4-GHz 1-, 2-, and 3-pole microstrip quasi-reflectionless bandpass filters. Measured frequency responses of these filters closely match those of the simulation.

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A Wideband Bandpass Filter with Broad Stopband and Ultra-Wide Reflectionless Range for 5G Applications

Cited by 21 publications

References 6 publications

A Low-Cost Microwave Filter with Improved Passband and Stopband Characteristics Using Stub Loaded Multiple Mode Resonator for 5G Mid-Band Applications

A Low-Cost Microwave Filter with Improved Passband and Stopband Characteristics Using Stub Loaded Multiple Mode Resonator for 5G Mid-Band Applications

An X‐band centrosymmetric microstrip bandpass filter with reflectionless range over 3.9–18.6 GHz and stopband up to 40 GHz

Quasi-Reflectionless Microstrip Bandpass Filters With Improved Passband Flatness and Out-of-band Rejection

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