Dual-band differential bandpass filter using stepped impedance resonators

In this article, two high selectivity balanced filters with multiple transmission zeros using ring resonators are proposed. Four, and six transmission zeros are easily realized to improve the differential mode passband selectivity and common mode suppression. Over five octaves common mode suppression can be realized by the bandstop performance of the coupled lines and stubs. Two balanced filters with 3-dB bandwidths of 23.6 and 23.5% are designed and measured. Good agreement can be found between the theoretical and measured results. | I NT ROD UCTI ONBalanced circuits including filters, power dividers, and diplexers are becoming more and more important components, due to their environmental noises suppression, better dynamic range, and lower electromagnetic interference in RF/microwave communication systems.1,2 Different techniques such as cascaded couplers, double-sided parallel-strip lines, microstrip-slot-microstrip structures, T-shaped structures are used to design single/dual-band, and wideband balanced filters with common mode suppression. [3][4][5][6][7] The main advantages of these balanced filters in 3-7 are the high selectivity near the differential mode passband, however, the out-of-band harmonic suppression for the differential mode and the common mode suppression are not so ideal due to lack of transmission zeros. In our former woks, 8 two high selectivity balanced filters with two and four transmission zeros near the differential passband are realized, and the common mode suppression can be extended over five octaves. In this work, another two Figure 1A,B are shown in Figure 2, due to the added half-wavelength open stubs of Figure 1B, two transmission zeros are located at 0.5f 0 and 1.5f 0 . When the filter of Figure 1B is used to design balanced filters, the ring resonator with asymmetrical shorted/open stubs can be used to realize a high selectivity passband for the differential mode with four transmission zeros, and the dual-mode ring resonator with asymmetrical open stubs can be used to suppress the common mode over a wide frequency band. Next, detailed theoretical design for the two balanced filters with four/six transmission zeros will be given.Int J RF Microw Comput Aided Eng. 2018;28:e21174.

Section: Measured Results and Discussionmentioning

confidence: 99%

Section: Eas U Red R Es Ult S and Discussionsmentioning

confidence: 99%

High selectivity balanced filters with multiple transmission zeros using ring resonators with loaded stubs

Deng

Chen

Feng

2017

“…Differential topology is widely applied in constructing microwave circuits and systems because of its high immunity to noise and crosstalk. Corresponding to this trend, many devices have been designed in differential configuration, such as power dividers, phase shifters, antennas, and filters . In earlier works, the differential bandpass filters (BPFs) have been extensively developed by using various technologies, such as the printed circuit board, the low temperature co‐fired ceramic, and the substrate integrated waveguide .…”

Section: Introductionmentioning

confidence: 99%

Compact differential dual‐band bandpass filter using single quad‐mode metal‐loaded dielectric resonator

Yuan

Zhou

2019

This letter presents a novel miniaturized differential dual‐band bandpass filter (BPF) using a single quad‐mode metal‐loaded dielectric resonator (DR). The differential dual‐band BPF is designed in a single‐cavity configuration with one quad‐mode DR and four feeding probes, featuring compact size. The rectangular DR is directly mounted on the bottom of the metal cavity and covered by a metal plate on the top surface. It allows two pairs of orthogonal modes (LSE10 and LSM10), which can be differentially excited and coupled by introducing proper perturbation for constructing dual‐band differential‐mode frequency response. To validate the proposed idea, a compact differential BPF with good performance using a quad‐mode DR cavity is designed, fabricated, and measured. The simulated and measured results with good agreement are presented.

“…Balanced circuits with higher immunity to environmental noises, lower electromagnetic interference, and better dynamic range are important components in modern circuits and systems . In recent years, several different balanced circuits, such as filters, crossovers, power dividers, diplexers, and active circuits were proposed . The main attentions of former works are mainly paid to design balanced‐to‐balanced circuits, and the power division ports isolation are not so ideal due to lack of isolation resistors.…”

Section: Introductionmentioning

confidence: 99%

Balanced power dividers with improved bandwidth using folded lines

Feng

Che

2017

Two novel wideband balanced‐to‐unbalanced power dividers based on transmission lines and coupled lines are proposed in this article. Multifunction can be realized without cascading single devices with common mode suppression. The desired power divider configurations can be obtained using the even/odd‐mode characteristic impedance of the coupled lines and characteristic impedance of the transmission lines. A resistor in the middle of two single‐ended ports is used to realize isolation between output ports. Two prototypes of wideband balanced‐to‐unbalanced power dividers operating at 2.3 GHz with differential‐mode bandwidths of 79.6 and 134.1% are designed and fabricated. The theoretical and measured results are in good agreement and show good in‐band performances.