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This letter proposes a wide-range reconfigurable bandpass filter (WRBPF) based on the cross-shape triple-mode resonator. Varactor diodes and switching diodes are utilized at the ends of the resonator and the positions of external coupling, which combines the two working modes of the low-frequency band and high-frequency band, greatly broaden the tunable range of the center frequency ($f_{0}$). When the 3-dB bandwidth of WRBPF is 180 MHz, $f_{0}$ can be adjusted from 0.78 to 1.93 GHz, and the relative adjustment range is 84.9%. When $f_{0}$ is 1.355 GHz, the absolute bandwidth can be adjusted from 110 to 950 MHz, and the relative bandwidth adjustment range is 8.1%–70.1%. Moreover, the circuit size of WRBPF is only $0.29\,\,\lambda g\,\,\times 0.22\,\,\lambda g$. The experimental results show that WRBPF has not only a simple structure but also an excellent performance. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvester (PEH) arrays are practical solutions to the low and unreliable power output of a single PEH. However, most PEH circuits are developed for addressing the one-channel ac input from a single PEH. In this article, an extensible rectifier-less synchronized switch harvesting on inductor (ReL-SSHI) array interface with the maximal power point tracking (MPPT) function to manage the multiple ac inputs from the PEH arrays is designed. The ac–dc conversion is performed by the ReL-SSHI topology with passive peak switches featured with self-powered characteristic and fast cold-start. Only one shared inductor is employed, greatly reducing the circuit volume and cost. The MPPT module for each channel is implemented by a simple envelope detector and an ultra-low power hysteresis controller and achieves continuous energy extraction by adapting the fractional normal-operation voltage method. A developed discrete array interface able to handle three PEHs effectively executes the MPPT for each channel with the uphill and downhill response speeds of 2.0 and 7.1 V/s, and a maximal MPPT efficiency of 97.1%. This circuit boosts the power output by 485% compared with that by the traditional full-bridge rectifier, around 33% higher than that from existing synchronous electric charge extraction array interfaces. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvester (PEH) arrays are promising in many application scenarios. However, few interface circuits have been developed to manage the multiple ac inputs from PEHs. This article proposes an extensible parallel synchronized switch harvesting on inductor array interface scheme to realize a multiinput conversion from PEH arrays. We develop a split-inductor-capacitor topology that can extract electrical energy from multiple PEHs. The proposed circuit topology effectively handles the inductor access conflict in the cases of PEHs with close, identical, and opposite vibration phases, insensitive to ac input phase changes. For demonstrating the capability of dealing with multiple ac inputs from PEHs and the enhancement effect on power output, we construct and test a self-powered three-channel array circuit with the passive peak detection function. Excited by sinusoidal vibrations, our circuit effectively avoids the energy return and efficiently achieves the power combination of the three PEHs. Compared with the classic full-bridge circuit, the proposed circuit helps increase the power output by 4.8 times. Also, to show the universality of the circuit, the circuit's operation under various excitations istested and analyzed. [ABSTRACT FROM AUTHOR]

A channel-continuous triplexer (CCT) with multiple transmission zeros (TZs) is designed and processed by cascading the high-pass filter (HPF) and low-pass filter (LPF) through the matching branches. The CCT is realized based on the substrate integrated suspended line (SISL) technology. The out-of-band suppression (OBS) and roll-off rate (ROR) of CCT are improved by the TZs introduced by cross-coupling lines between the nonadjacent branches in the HPFs and high-low impedance microstrip line T junction in LPFs. The experimental results show that CCT covers 4–7 GHz by three continuous bandwidth-identical passbands with the fractional bandwidths (FBWs) of 22.2%, 18.1%, and 15.3%, respectively. The insertion loss within three passbands is less than 1.7 dB, the out-of-band rejection is more than 50 dB, and the ROR is greater than 200 dB/GHz. [ABSTRACT FROM AUTHOR]

To merge the gap between the low-power output of piezoelectric energy harvesters (PEHs) and the high-power demand of sensors of Internet of Things, researchers recently start to explore PEHs arrays. However, few circuits have been developed to manage the multiple ac inputs from PEHs arrays. This article presents a self-powered PEH array interface circuit based on the synchronized switching and discharging to a storage capacitor through an inductor (SSDCI) technique. The array interface can output a maximum total power greater than the sum of each individual peak power, and achieve a high efficiency when multiple PEHs connect to the SSDCI array circuit. Simulation and experiment are performed to demonstrate the advantages of the SSDCI array interface. The tested results show that the designed SSDCI array circuit achieves an efficiency of 82.3% with three input sources, and allows a gain up to 300% in terms of maximal output power compared to the full-bridge rectifier. In addition, only the peak detection is utilized for the switching control; therefore, the SSDCI array circuit is realized more easily and with fewer components compared to the existing synchronous electric charge extraction array interfaces. [ABSTRACT FROM AUTHOR]

A novel multimode dual-ring ultrawideband (UWB) bandpass filter is proposed in this article, which is constructed by loading open stubs in the horizontal and vertical directions of the dual-ring resonator. Five modes are evenly distributed in the passband, and a pair of transmission zeros are introduced to the left and right transition bands to enhance selectivity. Parallel-coupled lines ensure external coupling strength for realizing the UWB, and a cross junction suppresses spurious in high frequencies to expand the upper stopband. For demonstration, a quintuple-mode high-temperature superconducting UWB bandpass filter is designed on the 0.5 mm thick MgO substrate with double-sided YBa2Cu3O7 (YBCO) films. The test results show that the 3-dB bandwidth covers 2.56 to 11.15 GHz, the in-band return loss greater than 15 dB. [ABSTRACT FROM AUTHOR]

A miniaturized eight-order quasi-elliptic function filter configuration with controllable transmission zeros (TZs) is proposed. Without changing the overall layout of the filter, two pairs of TZs are introduced by adopting two cascaded quadruplet (CQ) units to improve the suppression of the filter. At the same time, a cross capacitance coupling is introduced to combine the two CQ units to realize the synchronous adjustment of these two pairs of TZs. Through using this configuration, it not only helps realize the miniaturization of the filter, but also reduces the complexity of adjusting the two CQ units individually. Finally, an eight-order high-temperature superconducting filter with two pairs of TZs is designed on a double-sided YBCO/MgO/YBCO thin film with a size of 15.95 mm × 7.91 mm, a thickness of 0.5 mm, and a dielectric constant of 9.8. At 77 K, the measured central frequency of the filter is 2000 MHz, the bandwidth is 35 MHz, the out-of-band rejection is greater than 60 dB/MHz, the insertion loss is less than 0.22 dB, the return loss is better than 15.8 dB, and the test results are in good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

A new method is proposed to produce even finite transmission zeros without any cross-coupling between the resonators of filter, by loading the second-order extracted-pole unit (EPU) composed of two mutual coupled resonators at the input or output port of the filter. An arbitrary distribution of finite transmission zeros on the imaginary axis can be achieved by adjusting the resonant frequencies of resonators in the EPUs and the coupling strength between them. The finite transmission zeros can be symmetrically or asymmetrically distributed about the center frequency of the filter, even all on the same side outside the passband of the filter. And the topological structures of these filters are given in this paper. Besides, Cauchy method is adopted to analyze the proposed EPU configuration filter as well. This paper not only discusses how to implement a pair and two pairs of finite transmission zeros, and how to control the distribution of finite transmission zeros, but also gives multiple sets of computer-aided synthesized normalized coupling matrices. Based on this, an eighth-order quasi-elliptic function high-temperature superconducting filter with two pairs of finite transmission zeros was designed on a double-sided YBCO/LaAlO3/YBCO films to verify the feasibility of this new structure. [ABSTRACT FROM AUTHOR]

In this paper, a novel trapezoidal meander-line resonator (TMLR) is proposed to design compact high-order high-temperature superconducting (HTS) linear phase bandpass filters with cascaded quadruplet (CQ) structures. By changing the conventional rectangle half-wavelength meander-line microstrip resonator into a trapezoidal resonator, unnecessary cross coupling between nonadjacent resonators in the CQ units can be avoided. And using the proposed TMLR to design the CQ unit, electric field cross coupling or magnetic field cross coupling can be easily achieved and tuned without the cross-coupling line. To further demonstrate the feasibility of using this configuration for miniaturized circuit design, an 8-order HTS linear phase filter with one pair of transmission zeros was designed. The measured responses agree very well with the simulated results. The physical HTS filter has a center frequency of 1935 MHz and bandwidth of 70 MHz. The out-of-band rejection is greater than 50 dB, and the effective bandwidth of group delay fluctuation less than ±3 ns takes up more than 65% in the whole passband. [ABSTRACT FROM AUTHOR]

A novel compact high-temperature superconducting low-pass filter (LPF) with an ultrawide stopband, excellent out-of-band rejection, and a low insertion loss is presented. This filter consists of a four-order LPF constructed by four interdigital hairpin stepped-impedance resonators (IHSIRs) and two pairs of radial stubs (RSs) in the input and output ports of the filter. The four-order IHSIR LPF brings transmission zeros for a high selectivity, and the RSs exhibit a characteristic of extending the LPF’s stopband effectively. The proposed LPF with cutoff frequency $f_{c}$ at 3 GHz is implemented on a 0.5-mm-thick MgO wafer with double-sided YBCO films. The measured results show a 30-dB harmonic suppression from $1.08f_{c}$ to $7f_{c}$ , a steep roll-off of 197.1 dB/GHz, and an in-band insertion loss less than 0.13 dB. Moreover, the LPF possesses a miniaturized size of $0.21\lambda _{\text {gc}} \times 0.03\lambda _{\text {gc}}$. [ABSTRACT FROM AUTHOR]

This letter presents a new multimode ring resonator ultrawideband (UWB) bandpass filter by loading a microstrip line on the vertical symmetrical plane of a ring resonator and a pair of stepped-impedance open stubs at the center of this microstrip line. Five modes are allocated within UWB band, and a pair of transmission zeros are introduced to improve the passband selectivity. By adopting the parallel-coupled lines, not only suitable external coupling is achieved, but also the performance of upper stopband is improved. This quintuple-mode high-temperature superconducting UWB filter is designed on a 0.5-mm-thick MgO substrate with double-sided YBCO films. The measured results show that 3-dB bandwidth covers 1.57–6.51 GHz, the return loss is better than 10.70 dB, the out-of-band rejection is greater than 24.75 dB in the lower stopband, and the upper stopband with 20-dB attenuation level is extended to about 9 GHz. [ABSTRACT FROM AUTHOR]