A Dual-Wideband Balanced Bandpass Filter Based on Branch-Line Structure With Controllable Common-Mode Suppression

In this paper, a novel dual-wideband balanced bandpass filter (BPF) based on branch-line structure is proposed. For analysis, the equivalent circuits of differential-mode (DM) and common-mode (CM) of the filter are built based on the even- and odd-mode method. With a proper synthesis design of DM bisection, dual passbands with a multi-order filtering response can be obtained. Additionally, three open-circuited stubs are centrally loaded on the CM bisection and six controllable transmission zeros are therefore generated. Thus, two stopbands are formed and then a favorable CM suppression within DM passbands is obtained. For demonstration, a third-order dual-wideband balanced BPF is designed with two passbands operating at 2.54 and 4.62 GHz. Good agreement between the simulated results and measured results is obtained, which verifies the validity of the proposed design method.

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Design of differential-mode bandpass filter with common-mode suppression using ring dielectric resonator

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078716001306 ◽

2016 ◽

Vol 9 (5) ◽

pp. 1029-1035 ◽

Cited By ~ 2

Author(s):

Jugul Kishor ◽

Binod K. Kanaujia ◽

Santanu Dwari ◽

Ashwani Kumar

Keyword(s):

Dielectric Resonator ◽

High Performance ◽

Bandpass Filter ◽

Ring Resonator ◽

Differential Mode ◽

Common Mode ◽

Mode Suppression ◽

Transmission Zeros ◽

System A ◽

Good Agreement

Synthesis of differential-mode bandpass filter (BPF) with good common-mode suppression has been described and demonstrated on the basis of ring dielectric resonator (RDR) for high-performance communication system. A RDR with two pairs of feeding lines has been used to excite TE01δ-mode. This unique combination of feeding lines and the ring resonator creates a differential passband. Meanwhile, TM01δ-mode of the DR can also be excited to achieve common-mode rejection in the stopband. Transmission zeros are created in the lower and upper stopband to further improve the selectivity of the proposed BPF. A second-order differential BPF is designed, fabricated and its performance is measured to validate the concept. There is good agreement between simulated and measured results.

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Design of differential mode wideband bandpass filter with Common mode suppression using modified branch line coupler

2015 International Conference on Smart Technologies and Management for Computing, Communication, Controls, Energy and Materials (ICSTM) ◽

10.1109/icstm.2015.7225423 ◽

2015 ◽

Cited By ~ 1

Author(s):

Sachin Kumar ◽

I. Srinivasa Rao

Keyword(s):

Bandpass Filter ◽

Differential Mode ◽

Common Mode ◽

Branch Line ◽

Mode Suppression

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A Balanced Filtering Directional Coupler with Wide Common-Mode Suppression Based on Slotline Structure

Electronics ◽

10.3390/electronics10182254 ◽

2021 ◽

Vol 10 (18) ◽

pp. 2254

Author(s):

Luyan Qiao ◽

Rui Li ◽

Ying Han ◽

Feng Wei ◽

Yong Yang ◽

...

Keyword(s):

Communication Systems ◽

Directional Coupler ◽

Design Method ◽

Wireless Communication Systems ◽

Common Mode ◽

Mode Suppression ◽

Transmission Zeros ◽

The Common ◽

Better Than ◽

Good Agreement

In this paper, a balanced-to-balanced filtering directional coupler (FDC) that can realize a 3 dB coupling degree directional coupler with high isolation and directivity is proposed. The design of the proposed FDC is primarily based on microstrip/slotline transition structures, resonance structures, and odd–even mode phase velocity compensation structures. A U-type microstrip feed line integrated with a stepped-impedance slotline resonator is adopted at the input and output ports, which makes the differential-mode (DM) responses independent of the common-mode (CM) ones, and brings superior DM transmission and CM suppression. In addition, by loading the microstrip stub-loaded resonators (SLRs), a DM passband with sharp filtering performance is realized, and transmission zeros (TZs) can be added into the design, which makes it more selective. Moreover, phase compensating slotlines are added into the coupling structure to enhance the isolation. In order to verify the feasibility of the proposed design method, an FDC prototype circuit was made and tested. The simulation results are in good agreement with the measured results. The designed coupler’s DM operating band covers 2.65 GHz to 3 GHz (FBW = 12.4%), and the insertion and return losses are 4.6 dB and 20 dB, respectively. The isolation degree is better than 15 dB, and the CM suppression is more than 55 dB. The total coupler size is about 67.7 mm × 63.8 mm. The designed balanced-to-balanced FDC can be widely used in S-band wireless communication systems.

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