Tunable Filtering Power Divider Research Articles

Reconfigurable triple‐band filtering power divider with continuously tunable center frequency using multimode resonators

AbstractIn this paper, a reconfigurable microstrip triple‐band filtering power divider (FPD) is proposed with continuously independent tunable center frequency (CF) by using varactor‐loaded triple‐mode resonators. The proposed tunable FPD is basically composed of a pair of varactor‐loaded triple‐mode resonators, a common input line, a pair of coupled output lines, and an isolation resistor. Based on the proposed topology, the employed triple‐mode resonators and the input/output are reasonably arranged to achieve desired triple‐passband filtering power division response. To demonstrate the feasibility of the design concept and method, a reconfigurable triple‐band FPD is designed and fabricated. The CFs of the three passbands can be adjusted independently, the frequency tuning ranges of triple‐bands are 1.63–1.79, 2.0–2.11, and 2.26–2.33 GHz with good return loss and high port‐to‐port isolation, respectively.

A Tunable Vector-Sum Filtering Power Divider With Continuously Tuned Frequency and Arbitrary Output Phase Difference

A novel tunable vector-sum filtering power divider (FPD) with arbitrary output phase difference is proposed. It is constructed by a tunable FPD [which has reconfigurable in-/out-of-phase output and arbitrary power division ratios (PDRs)] on the left and a wideband branch-line coupler (BLC) on the right. The output wave from the left FPD forms two orthogonal vectors at each output port of the BLC. The orthogonal vectors are summed up and result in a new vector with phase that is purely determined by the amplitude ratio of the orthogonal vectors. As a result, the phase difference between the new vectors at the outputs of the BLC can be continuously tuned by adjusting the PDR of the left FPD. Detailed theoretical analysis has been given. It shows that the phase difference between the output ports can be flexibly tuned from 0 °C to 360 °C within the full frequency tuning range.

Reconfigurable quasi‐elliptic filtering power divider with continuously tunable centre frequency and bandwidth

This study presents a new reconfigurable quasi-elliptic filtering power divider (FPD) with tunable centre frequency (CF) and bandwidth (BW) by exploring singly one varactor-loaded triple-mode resonator. Avoiding the need for the variable couplings of the inter-resonant nodes and external input/output, the reconfigurability of the proposed FPD is achieved by only tuning the resonant nodes of the triple-mode resonator. Compared to the other reported ones, the proposed FPD not only exhibits better performance, but also compact and concise topology with the reduced number of resonators and loaded varactors. For demonstration, a prototype of tunable FPD is implemented following the given design procedure. Measured results coincide well with simulated ones, exhibiting that tunable CF (1.5–1.91 GHz), 1-dB BW (80–300 MHz) with better in-band isolation (>18 dB).

Design Method for Compact Multifunctional Reconfigurable Filtering Power Divider on a New Tunable Three-Port Multi-Mode Topology

In this paper, a new effective approach is proposed to design compact multifunctional reconfigurable filtering power divider (FPD) based on a developed tunable multi-mode FPD topology. Different from conventional tunable FPD method by cascading tunable filter with power divider (PD), and double tunable filtering structures based on the tunable FPD method, it provides one promising solution of high operation performance, miniaturization and design flexibility enhancement etc., for industrial multi-functional modern wireless communication systems. By reformulating the traditional coupling matrix in terms of element-variable coupling coefficients for the developed tunable FPD topology, bandwidth (BW), center frequency (CF), as well as power division ratio (PDR) tuning are well accounted, which can help guide a new class of tunable FPD designs. For demonstration, a new second-order tunable FPD with only one common ring loaded coupled line tunable resonant unit is implemented as an example without losing generality. Higher-order tunable FPD case is further discussed and investigated by freely generalizing the FPD structure through the adoption of different tunable resonant units without dramatically increasing circuit complexity and size. Experimental results indicates that an improved performance (wider tuning range for CF, BW and PDR with nice isolation and matching), a very compact size and flexible design are achieved in the proposed work, which stands out from those in the literature.

Tunable balanced to balanced filtering power divider with high common-mode suppression

Abstract In this paper, a tunable balanced-to-balanced in-phase filtering power divider (FPD) is designed, which can realize a two-way equal power division with high selectivity and isolation. A differential-mode (DM) passband with a steep filtering performance is realized by applying microstrip stub-loaded resonators (SLRs). Meanwhile, six varactors are loaded to the SLRs to achieve the center frequency (CF) and bandwidth adjustment, respectively. U-type microstrip lines integrated with stepped impedance slotline resonators are utilized as the differential feedlines, which suppress the common-mode (CM) intrinsically, making the DM responses independent of the CM ones. A tuning center frequency from 3.2 to 3.75 GHz and a fractional bandwidth (12.1–17.6%) with more than 10 dB return loss and less than 2.3 dB insertion loss can be achieved by changing the voltage across the varactors. A good agreement between the simulated and measured results is observed. To the best of authors' knowledge, the proposed balanced-to-balanced tunable FPD is first ever reported.

Review of Recent Developments in Microwave Power Divider

In previous years, different objectives and designs of power divider (PD) were proposed for modern wireless communication systems, such as filtering power divider (FPD) and tunable power divider. In this paper, a review on various sorts of filtering and tunable power divider is presented. There are several designs which are novel in their techniques, while others are motivated from previous works. This paper begins with an introduction on power divider, followed by the description of available designs for tunable power divider and filtering power divider. Furthermore, the designs' size, measurement, performance and technology used are also discussed. Most of the existing designs for tunable power divider use varactors for tunable properties. Meanwhile, for filtering power divider, the designs mostly focus on fixed operational bands and frequencies of filtering power divider due to simple design procedures. Therefore, an alternative design for filtering power divider is suggested which integrates the tunable power divider and filtering power divider. However, there are a few works that focus on tunable filtering power divider. From previous works, varactors or pin diodes are used to make tunable filtering power divider.

Quasi‐lumped dual‐mode reconfigurable eight‐way FPD

A quasi-lumped dual-mode reconfigurable eight-way filtering power divider (FPD) is presented. Two operating modes are one eight-way tunable FPD and one all stopband filter (ASF) with high suppression. The measured eight-way FPD can be tuned from 1.0 to 2.15 GHz, corresponding to the frequency tuning range (FTR) of 73%. The ASF is obtained by misaligning resonant frequencies of LC resonators and weakening their coupling. The proposed dual-mode FPD has the advantage of wide FTR, compact size, high isolation, ultra-wide isolation BW, and high suppression.

High selectivity tunable filtering power divider based on liquid crystal technology for microwave applications

A novel electrically tunable filtering power divider, based on liquid crystal (LC) technology, is designed and experimentally demonstrated in this paper. Using low-cost T-shaped inverted-microstrip structures integrated with two dual-mode open-loop resonators, the tunable power divider possesses bandpass-filtering frequency response. Moreover, transitions between inverted-microstrip and microstrip structures are specifically designed at the I/O ports for the self-packaged. The experimental results indicate that the central frequency can be tuned from 5.75 to 6.25 GHz, i.e. a relative tuning range of 8.3%, the 3-dB bandwidth is 6.8 ± 0.2% over the whole tuning range, and the maximum amplitude and phase imbalance are less than 0.8 dB and 2.5°, respectively. In addition, the proposed filtering power divider has three transmission zeros to improve the frequency selectivity.