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Aiming at high and wideband output isolation, a new topology of filtering power divider based on complex isolation impedance and surface wave mitigation techniques is proposed. Different from previously published filtering power dividers using pure resistor, an analytical design method by using complex impedance is proposed in this article. To formula the complex impedance, the LC equivalent circuit model is introduced, and the closed-form derivation is given accordingly. Based on the calculated impedance, high isolation can be theoretically realized in circuit level. However, the output isolation is limited below 20 dB in practical EM simulations. To solve this issue, the filtering power divider is further investigated in field level. To reduce the crosstalk between adjacent filtering channels, the surface wave mitigation techniques are investigated. Accordingly, a 16-dB enhancement of output isolation is realized, without sacrificing other filtering specifications. For experimental verification, a filtering power divider is designed, fabricated, and measured. A significant size reduction and 36-dB output isolation with over 500% isolation bandwidth can be observed, verifying the validity of the proposed design method. [ABSTRACT FROM AUTHOR]

Two new types of multi-functional RF wide-band differential-mode-to-single-ended filtering power dividers are reported in this brief. Their first configurations exploit half-wavelength ring resonators and coupled-line sections to attain common-mode suppression throughout a broad spectral range. Furthermore, asymmetrical coupled-line stages are incorporated in more-advanced schemes to enlarge upper-stopband bandwidth. Two demonstrative microstrip prototypes for the different structures of this RF tri-functional circuit concept that operate at the 1.7–2.7-GHz 4/5-generation long-term-evolution band are built and tested. [ABSTRACT FROM AUTHOR]

Two novel high selectivity balanced-to-unbalanced filtering power dividers using ring resonators are proposed. The even-/odd-mode analysis method is applied to obtain the design equations at the operating frequency. The ring resonators can bring two transmission zeros in each side of the passband for the differential mode for the filtering power divider (structure I). Moreover, the three-quarter wavelength transmission lines are applied to produce the additional two transmission zeros of differential mode for structure II, which can further improve the differential-mode harmonic suppression and common-mode suppression. Two fabricated prototypes with 4-dB bandwidths of 11.2% and 11.6% are designed and measured to prove the proposed methods. All the structures show good performances for differential-mode power division and common-mode suppression. [ABSTRACT FROM AUTHOR]

One kind of miniaturized filtering power divider (FPD) with a new topology is proposed. For previously published FPDs, the isolation resistors were usually added with additional quarter-wave ($\lambda $ /4) transmission lines for output isolation. In this paper, $\lambda $ /4 transmission lines are removed, and the resistor is added to the loaded resonator for the miniaturized design. By regarding the input external quality factor ($Q_{e\text {-in}}$) as an admittance inverter, the indispensable 90° delay can be easily realized. To further improve the miniaturization, the dual-composite right-/left-handed (D-CRLH) resonators are adopted; therefore, the overall sizes of the resulting FPDs can be smaller than $0.012\lambda _{g}^{2}$. Moreover, the equivalent circuit of the proposed FPD is investigated for the performance improvement. Input $Q_{e\text {-in}}$ should be double of output $Q_{e\text {-out}}$ for good matching, and good isolation can be obtained by appropriately utilizing $Q_{e\text {-in}}$. For demonstration, three D-CRLH FPDs are designed for narrowband, wideband, and dual-band applications. Satisfactory agreements between the measured results and theoretical expectations are observed, verifying the validity of the proposed design concepts. [ABSTRACT FROM AUTHOR]

Three novel wideband balanced-to-unbalanced filtering power dividers based on coupled lines are proposed in this paper. Multifunctional power dividers can replace various cascaded single devices to decrease integration mismatching loss and circuit size. The wideband response can be easily realized by the coupled lines structures. To further improve the differential-mode passband selectivity, open/shorted coupled lines and half-wavelength open stubs are applied to introduce two transmission zeros near the passband, respectively. In addition, a resistor in the middle of two single-ended ports can be used to realize isolation between out ports. To verify the proposed concepts, three prototypes of wideband balanced-to-unbalanced filtering power dividers operating at 2 GHz are designed and fabricated with the 4-dB differential-mode bandwidths of 80.5%, 71.5%, and 80%. All the structures show good performances for differential-mode out-of-band suppression, common-mode suppression, and isolation. [ABSTRACT FROM PUBLISHER]

A compact four-way dual-band microstrip power divider is investigated and demonstrated in this letter. The proposed divider reduces the number of transmission line sections by decomposing a single dual-band transformer into a four-way power divider. The theoretical equations for isolation structures and the design procedures of the power divider are presented. For demonstration, a prototype operating at 1 and 2 GHz is fabricated and measured. Good agreements can be observed between the simulated and measured results. [ABSTRACT FROM PUBLISHER]