Showing papers on "Prototype filter published in 2016"
TL;DR: In this paper, several passive filter topologies used to interface voltage-source converters with the utility grid are reviewed and evaluated in terms of damping capability, stored energy in the passive components, and power loss in the damping circuit.
Abstract: In order to reduce size and cost, high-order passive filters are generally preferred in power converters to cancel out high-frequency harmonics caused by pulsewidth modulation. However, the filter resonance peaks may require the use of passive dampers to stabilize the interactions between the load and source impedances. Furthermore, the stabilizing effect is more difficult to be guaranteed for cost-optimized filters, which are characterized by low-inductance and high-capacitance passive components. In this paper, several passive filter topologies used to interface voltage-source converters with the utility grid are reviewed and evaluated in terms of damping capability, stored energy in the passive components, and power loss in the damping circuit. In addition, the influences of different switching frequencies of power converters on the passive filter design are discussed in the range 1–15 kHz. Illustrative design examples of the passive filters and experimental data are also provided.
369 citations
TL;DR: In this paper, a new method is proposed to optimally design the passive damping circuit for the LCL filters and LCL with multituned LC traps, which simplifies the iterative design of the overall filter while ensuring the minimum resonance peak with a lower damping capacitor and a lower rated resistor.
Abstract: Harmonic stability problems caused by the resonance of high-order filters in power electronic systems are ever increasing. The use of passive damping does provide a robust solution to address these issues, but at the price of reduced efficiency due to the presence of additional passive components. Hence, a new method is proposed in this paper to optimally design the passive damping circuit for the LCL filters and LCL with multituned LC traps. In short, the optimization problem reduces to the proper choice of the multisplit capacitors or inductors in the high-order filter. Compared to existing design procedures, the proposed method simplifies the iterative design of the overall filter while ensuring the minimum resonance peak with a lower damping capacitor and a lower rated resistor. It is shown that there is only one optimal value of the damping resistor or quality factor to achieve a minimum filter resonance. The passive filters are designed, built, and validated both analytically and experimentally for verification.
195 citations
TL;DR: In this paper, the authors present different coupling mechanisms and feeding techniques for the design of quarter-mode SIW filters: side coupling and corner coupling are considered, highlighting the advantages and disadvantages of the two techniques.
Abstract: This paper presents a systematic investigation of quarter-mode filters in substrate integrated waveguide (SIW) technology. This class of filters is particularly convenient because it combines the features of SIW structures with the improvement of size reduction. After a thorough analysis of the quarter-mode SIW cavity, this paper presents different coupling mechanisms and feeding techniques for the design of quarter-mode SIW filters: side coupling and corner coupling are considered, highlighting the advantages and disadvantages of the two techniques. Novel filter topologies are introduced, with the design and experimental verification of simple filters and their extension to higher order filter structures. Techniques to introduce transmission zeros are described and demonstrated. Moreover, the combination of quarter-mode SIW cavities and coplanar waveguide resonators leads to increasing the filter order to higher order and allows the implementation of quasi-elliptic filters.
119 citations
TL;DR: In this paper, two W-band waveguide bandpass filters were fabricated using laser micromachining and 3-D printing techniques, one fabricated from a single metal workpiece and the other from polymer resin.
Abstract: This paper presents two W-band waveguide bandpass filters, one fabricated using laser micromachining and the other 3-D printing. Both filters are based on coupled resonators and are designed to have a Chebyshev response. The first filter is for laser micromachining and it is designed to have a compact structure allowing the whole filter to be made from a single metal workpiece. This eliminates the need to split the filter into several layers and therefore yields an enhanced performance in terms of low insertion loss and good durability. The second filter is produced from polymer resin using a stereolithography 3-D printing technique and the whole filter is plated with copper. To facilitate the plating process, the waveguide filter consists of slots on both the broadside and narrow side walls. Such slots also reduce the weight of the filter while still retaining the filter’s performance in terms of insertion loss. Both filters are fabricated and tested and have good agreement between measurements and simulations.
114 citations
TL;DR: It is shown that the proposed FBMC-QAM system satisfies the suggested orthogonality conditions and can use the multiple-input multiple-output transmission schemes as the conventional orthogonal frequency division multiplexing (OFDM) systems.
Abstract: A filter-bank multicarrier–quadrature amplitude modulation (FBMC-QAM) system with two prototype filters for transmitting QAM symbol is proposed, and the orthogonality conditions for the FBMC-QAM system without the intrinsic interference is derived. The proposed transmitter performs the individual filtering for the even and odd-numbered sub-carrier symbols, respectively. In order to satisfy the derived orthogonality conditions, we perform a sub-block wise reverse ordering procedure for the outputs of the odd-numbered sub-carrier filter. Also, this paper shows that the proposed FBMC-QAM system satisfies the suggested orthogonality conditions and can use the multiple-input multiple-output transmission schemes as the conventional orthogonal frequency division multiplexing (OFDM) systems. The signal-to-interference power ratio and the bit error rate (BER) for the proposed FBMC-QAM system are evaluated. Numerical results show that the proposed FBMC-QAM system has almost the same BER performance compared with the FBMC-OQAM and OFDM systems.
78 citations
01 Oct 2016
TL;DR: In this article, the authors present the different applications, challenges and trends for traditional active and passive harmonic filters for reduction of harmonic distortion and optimization of the power quality, and analyze the advantages and disadvantages of active versus passive filter technologies.
Abstract: The goal of this paper is to present the different applications, challenges and trends for traditional active and passive harmonic filters for reduction of harmonic distortion and optimization of the power quality. Emphasis is put on real cases applied in the industry for passive tuned filters and for active harmonic filters analyzing the advantages and disadvantages of active versus passive filter technologies.
72 citations
TL;DR: The results reveal that the proposed FIR filter design approach using cuckoo search algorithm outperforms other techniques in terms of design accuracy, execution time and optimal solution.
Abstract: Design of optimal filters is an essential part of signal processing applications. It involves the computation of optimal filter coefficients such that the designed filter response possesses a flat passband and up to an infinite amount of stopband attenuation. This study investigates the effectiveness of employing the swarm intelligence (SI) based and population-based evolutionary computing techniques in determining and comparing the optimal solutions to the FIR filter design problem. The nature inspired optimization techniques applied are cuckoo search, particle swarm and real-coded genetic algorithm using which the FIR highpass (HP) and bandstop (BS) optimal filters are designed. These filters are examined for the stopband attenuation, passband ripples and the deviation from desired response. Moreover, the employed optimization techniques are compared on the field of algorithm execution time, t -test, convergence rate and obtaining global optimal results for the design of digital FIR filters. The results reveal that the proposed FIR filter design approach using cuckoo search algorithm outperforms other techniques in terms of design accuracy, execution time and optimal solution.
70 citations
TL;DR: In this paper, a planar tunable capacitive coupling structure in substrate-integrated cavities using lumped components is presented, where both frequency and bandwidth tunable filters with adjustable transmission zero (TZs) are demonstrated.
Abstract: This paper expands our previous work on planar tunable capacitive coupling structures in substrate-integrated cavities using lumped components. We demonstrate both frequency and bandwidth tunable filters with adjustable transmission zeros (TZs). By the appropriate choice of the absolute and relative strength of magnetic and electric coupling coefficients, we demonstrate: 1) tunable bandwidth and the ability to maintain either a constant absolute bandwidth or a constant fractional bandwidth; 2) adjustable TZ location at a prescribed bandwidth; and 3) the ability to switch OFF the filter with high isolation. Filter design methodologies based on a dispersive coupling structure are presented using lumped circuit models, coupling matrix, and full-wave simulations. With this planar capacitive coupling, it is also convenient to realize cross-coupling in higher order filters to produce additional TZs for rejecting spurious resonances or interferes. Fabricated two-pole filters with one or two TZs and four-pole filters with three or four TZs validate the filter design. A two-pole filter with tunable center frequency and tunable bandwidth along with a four-pole filter with tunable center frequency and tunable TZs are also demonstrated.
61 citations
TL;DR: In this article, the authors presented a modeling technique for a hybrid commonmode (CM) filter, which is composed of an active filter and a passive filter to reduce the size and weight of conventional passive EMI filters.
Abstract: Hybrid electromagnetic interference (EMI) filters (HEFs), which are composed of an active filter and a passive filter, have been proposed to reduce the size and weight of conventional passive EMI filters in literatures. However, accurate models that can be used to predict the stability and performance of HEFs have not been developed. To cope with this, this paper presents a modeling technique for a hybrid common-mode (CM) filter. The technique can be applied to the modeling of other HEFs. Critical component models were first developed for the HEF. HEF's overall model was further developed based on these individual component models. Experimental results validated that the developed model can successfully predict the stability and performance of active/hybrid CM filters.
56 citations
TL;DR: In this paper, a pair of coupled stepped-impedance resonators and its use to build single and dual-band bandpass filter (BPF) is presented, where the adopted resonators are coupled at the two open-ended edges.
Abstract: A pair of coupled stepped-impedance resonators and its use to build single- and dual-band bandpass filter (BPF) is presented. To that end, two symmetrical stepped-impedance resonators with two embedded coupled-line sections are used. The adopted resonators are coupled at the two open-ended edges. The first even-mode resonant mode can be suppressed or excited based on whether it is required to realize a single- or dual-band response. Sharp passband selectivity and stopband harmonic suppression are achieved due to the existence of multiple transmission zeros. For verification, single- and dual-band filters using the proposed resonator are designed, fabricated and tested. The experimental results show a passband of 2.34–2.62 GHz (centered at 2.45 GHz for WLAN system), less than 1.5 dB insertion loss for the single-band filter; the dual-band design has two passbands ranged from 2.28–2.67 GHz and 3.35–3.63 GHz with less than 1.2 dB insertion loss for WLAN and WiMAX systems.
55 citations
TL;DR: This paper demonstrates that, despite feedback in IIR filters, these filters can be implemented using stochastic logic, and hardware synthesis results show that these filter structures require lower hardware area and power compared to two's complement realizations.
Abstract: This paper addresses implementation of digital IIR filters using stochastic computing. Stochastic computing requires fewer logic gates and is inherently fault-tolerant. Thus, these structures are well suited for nanoscale CMOS technologies. While it is easy to realize FIR filters using stochastic computing, implementation of IIR digital filters is non-trivial. Stochastic logic assumes independence of input signals; however, feedback in IIR digital filters leads to correlation of input signals, and the independence assumption is violated. This paper demonstrates that, despite feedback in IIR filters, these filters can be implemented using stochastic logic. The key to stochastic implementation is selection of an IIR filter structure where the states are orthogonal and are, therefore, uncorrelated. Two categories of architectures are presented for stochastic IIR digital filters. One category is based on the basic lattice filter representation where the states are orthogonal, and the other is based on the normalized lattice filter representation where states are orthonormal . For each category, three stochastic implementations are introduced. The first is based on a state-space description of the IIR filter derived from the lattice filter structure. The second is based on transforming the lattice IIR digital filter into an equivalent form that can exploit the novel scaling approach developed for inner product computations. The third is optimized stochastic implementation with reduced number of binary multipliers. Simulation results demonstrate high signal-to-error ratio and fault tolerance in these structures. Furthermore, hardware synthesis results show that these filter structures require lower hardware area and power compared to two's complement realizations.
TL;DR: A novel method of embedding phase-shifting functionality into the two-port N- path filter response by shifting the phase of the input and output clock sets relative to each other is introduced.
Abstract: N-path switched- RC circuits are a promising solution for realizing tunable high- Q filters on chip. Here, a novel method of embedding phase-shifting functionality into the two-port N- path filter response by shifting the phase of the input and output clock sets relative to each other is introduced. Furthermore, a two-port design allows us to embed variable attenuation that can be useful in applications such as wideband self-interference cancellers and phased-array front ends, where filtering, phase shifting, and variable gain are functionally required. The effect of the embedded phase shift is analyzed with linear periodically time-variant theory and has been verified through simulations and measurement. Measurement results are presented for a two-port N- path filter implemented in a 65-nm CMOS 0.8-1.4-GHz highly reconfigurable self-interference canceling receiver. The two-port filter achieves 13-dB gain control and full 360° phase-shift range for the in-band transfer function.
TL;DR: A new approach to the mean-square deviation (MSD) analysis of the MSAF algorithm is presented by using the persistently exciting input and the practical assumption that the stopband attenuation of the prototype filter is high.
Abstract: A multiband-structured subband adaptive filter (MSAF) algorithm was introduced to achieve a fast convergence rate for the correlated input signal. The convergence analysis of the adaptive filter algorithm is an important concept because it provides a guideline to design the adaptive filter. However, the convergence analysis of the MSAF algorithm has not been researched as extensively as that of the normalized least-mean-square algorithm. Therefore, it needs to be researched. In this paper, we present a new approach to the mean-square deviation (MSD) analysis of the MSAF algorithm by using the persistently exciting input and the practical assumption that the stopband attenuation of the prototype filter is high. Unlike the previous analysis, the proposed analysis is possible to be applied to the long-length adaptive filter such as the acoustic echo cancellation. The proposed analysis is also applied to a non-stationary model with a random walk of the optimal weight vector. The simulation results match with the theoretical results in both the transient-state and steady-state MSD.
TL;DR: The problem of noise reduction is addressed as a linear filtering problem in a novel way by using concepts from subspace-based enhancement methods, resulting in variable span linear filters that can be expressed as special cases of variable span filters.
Abstract: In this paper, the problem of noise reduction is addressed as a linear filtering problem in a novel way by using concepts from subspace-based enhancement methods, resulting in variable span linear filters. This is done by forming the filter coefficients as linear combinations of a number of eigenvectors stemming from a joint diagonalization of the covariance matrices of the signal of interest and the noise. The resulting filters are flexible in that it is possible to trade off distortion of the desired signal for improved noise reduction. This tradeoff is controlled by the number of eigenvectors included in forming the filter. Using these concepts, a number of different filter designs are considered, like minimum distortion, Wiener, maximum SNR, and tradeoff filters. Interestingly, all these can be expressed as special cases of variable span filters. We also derive expressions for the speech distortion and noise reduction of the various filter designs. Moreover, we consider an alternative approach, wherein the filter is designed for extracting an estimate of the noise signal, which can then be extracted from the observed signals, which is referred to as the indirect approach. Simulations demonstrate the advantages and properties of the variable span filter designs, and their potential performance gain compared to widely used speech enhancement methods.
TL;DR: In this article, a class of very compact dual-band band-pass filters based on TM dual-mode cavities loaded with high permittivity dielectric is presented.
Abstract: In this letter a class of very compact dual-band band-pass filters based on TM dual-mode cavities loaded with high permittivity dielectric is presented. Filters consist of cascaded doublets resulting in in-line structures with a high degree of design modularity where each doublet is designed separately. Each doublet provides two poles and two transmission zeros resulting in a filter with an equal number of poles and zeros. Zeros can be placed in both the lower and upper stop-bands as well as between the two pass-bands to increase their insulation. The feasibility of the proposed approach is demonstrated through the design and manufacturing of a 6th order dual-band filter with central frequencies at 4.25 and 4.55 GHz having six transmission zeros.
TL;DR: In this article, a dual-band bandpass filter with independently controlled passbands and constant absolute bandwidths (ABW) was proposed, and theoretical analysis and calculation were carried out to determine proper parameters of coupling regions.
Abstract: This letter presents a novel reconfigurable dual- band bandpass filter (DBBPF) with independently controlled passbands and constant absolute bandwidths (ABW). The design procedures follow the traditional synthesis approach of filters. Moreover, in order to meet the requirement of constant ABW, theoretical analysis and calculation are carried out to determine proper parameters of coupling regions. Finally, the proposed DBBPF exhibits 21.8% fractional tuning range of the first passband from 0.98 to 1.22 GHz and 17.9% of the second passband from 1.63 to 1.95 GHz, and 3-dB ABWs are 76 $\pm$ 4 MHz and 100 $\pm$ 4 MHz, respectively.
22 May 2016
TL;DR: In this paper, first-order reflectionless low-pass and band-pass filters were designed without using any sophisticated math techniques, and the results showed that the proposed filter structures have excellent return loss performances in the stopbands as well as in the passbands.
Abstract: This work presents design methods for first-order reflectionless lumped-element lowpass and bandpass filters. Each of the proposed filter structures contains an impedance matching circuit that can theoretically cancel out the reflected wave. We have derived the analytic design equations so that the reflectionless filters can be designed without using any sophisticated math techniques. In addition, by virtue of the design equations, the reflectionless lowpass and bandpass filters can be designed in a way to produce exactly the same transmitted power ratio as the conventional reflective filters. Both conventional reflective filters and proposed reflectionless filters have been fabricated and measured to verify the newly presented reflectionless filter design theory. The experimental results show that the proposed filter structures have excellent return loss performances in the stopbands as well as in the passbands. In addition, the measured transmitted power ratios of the reflectionless filters are not distinguishable of the reflective filters.
TL;DR: In this article, a balanced bandpass filter (BPF) with mixed electric and magnetic coupling is proposed, which is implemented by using $\lambda/4$ stepped-impedance resonators (SIRs).
Abstract: In this letter, a novel balanced bandpass filter (BPF) with mixed electric and magnetic coupling is proposed, which is implemented by using $\lambda/4$ stepped-impedance resonators (SIRs). Specially, balanced coupled-line is utilized to realize the passband response in differential-mode (DM) operation and meanwhile give a wide and deep stopband in common-mode (CM) operation. Second- and third-order equivalent half-circuits are investigated and simulated, which exhibits an excellent filtering performance for DM as well as a high level suppression in CM. A prototype balanced filter operating at 5.2 GHz is realized, which has controllable transmission zeros (TZs), sharp skirts, low inserted loss and compact size for DM. Under CM excitation, the measured level of suppression of signal is over 41 dB within the passband, over 38 dB from 0 to 9 GHz and over 26 dB from 0 to 16.5 GHz.
TL;DR: A straightforward and robust design procedure for the LCL-mT filter is proposed that satisfies the traditional practical limits on filter parameters, while ensures stability even in the presence of wide grid inductance variations and filter parameter uncertainties.
Abstract: Utilizing high-order passive filters for the voltage-source converters is becoming attractive in industrial applications due to the excellent attenuation performance, smaller size, and lower cost. The LCL , the multituned traps, and recently the combined LCL with multituned traps ( LCL-mT ) are the most popular high-order filters. However, the increased number of elements and the inherent resonances complicate both filter parameter design and current control loop stabilization, especially, in the presence of parameter uncertainties and wide variations of the grid inductance. Hence, in this paper a straightforward and robust design procedure for the LCL-mT filter is proposed. Compared to the existing methods, the proposed technique is not iterative and satisfies the traditional practical limits on filter parameters, while ensures stability even in the presence of wide grid inductance variations and filter parameter uncertainties. The validity and effectiveness of the proposed method are proved by simulation and experimental results.
TL;DR: Switched-capacitor fractional-step filter design of low-pass filter prototypes with Butterworth characteristics is reported for the first time using discrete-time integrators which implement both the bilinear and the Al-Alaoui s-to-z transformations.
Abstract: Switched-capacitor fractional-step filter design of low-pass filter prototypes with Butterworth characteristics is reported in this work for the first time. This is achieved using discrete-time integrators which implement both the bilinear and the Al-Alaoui s-to-z transformations. Filters of orders 1.2, 1.5 and 1.8 as well as 3.2, 3.5, and 3.8 are designed and verified using transistor-level simulations with Cadence on AMS $$0.35\,\upmu $$0.35μm CMOS process. Digital programmability of the fractional-step filters is also achieved.
TL;DR: In this paper, a class of tunable multi-band bandpass filters (BPFs) based on a quasi-bandpass topology is presented, which features a quasielliptic-type filtering response with controllable passbands in terms of center frequency and bandwidth.
Abstract: A class of tunable multi-band bandpass filters (BPFs) that is based on a quasi-bandpass topology is presented. Unlike other approaches, it features a quasi-elliptic-type filtering response with controllable passbands in terms of center frequency and bandwidth. Additional transmission zeros (TZs) are produced through cross couplings that are introduced between adjacent quasi-bandpass sections through their non-resonating nodes (NRNs). These TZs are synchronously tuned with passband reconfiguration. The lack of direct interaction among the resonating nodes of this multi-band BPF architecture results in a transfer function with high tuning robustness. Furthermore, when compared to prior-art coupled-resonator multi-band BPF designs, a reduced number of inverters are needed when synthesizing a large number of transmission bands. For the first time, the coupling-matrix formalism of the engineered multi-band BPF is expounded. In addition, a microstrip dual-band BPF prototype with mechanically-variable capacitors is manufactured and characterized for experimental demonstration purposes.
TL;DR: In this paper, a lumped-element dual-resonance resonator (LE-DRR) is proposed to design dual-band bandpass filter (DB-BPF) and reconfigurable filters.
Abstract: In this paper, a lumped-element dual-resonance resonator (LE-DRR) is proposed to design dual-band bandpass filter (DB-BPF) and reconfigurable filters. Two resonant modes of proposed LE-DRR are controlled by two diverse branches. The mixed electric and magnetic coupling (MEMC) implemented by two capacitors to provide electric coupling and one inductor to provide magnetic coupling is employed in the LE-DRR filters design. As an example, a 0.9/1.57-GHz DB-BPF with 3-dB fractional bandwidth (FBW) of 22.2%/11.8% is designed firstly. A reconfigurable DB-BPF with two independently controlled passbands is then designed. The measured results show that the central frequency (CF) of the 1st passband can be tuned from 0.617 to 0.817 GHz, and the CF of the 2nd passband can be tuned from 1.386 to 2.02 GHz. Finally, a multi-function reconfigurable filter is proposed by introducing two pairs of p-i-n diodes in the reconfigurable DB-BPF. The proposed multi-function reconfigurable filter has four operating modes, i.e., a reconfigurable DB-BPF operating mode, an all-stop filter operating mode, and two single-band tunable BPF operating modes. The all-stop filter operating mode has a 10.2-dB rejection within the interested frequency range. The CFs of two single-band tunable BPF operating modes can cover a continuous frequency range from 0.56 to 1.619 GHz. The proposed LE-DRR filters are compatible with an integrated circuit process.
TL;DR: In this article, a tunable single bandpass microwave photonic filter with an improved spurious free dynamic range (SFDR) using a dual-parallel Mach-Zehnder modulator (DP-MZM) and a phase-shifted fiber Bragg grating (PS-FBG) is proposed and experimentally demonstrated.
Abstract: A tunable single bandpass microwave photonic filter (MPF) with an improved spurious free dynamic range (SFDR) using a dual-parallel Mach–Zehnder modulator (DP-MZM) and a phase-shifted fiber Bragg grating (PS-FBG) is proposed and experimentally demonstrated. The DP-MZM is employed to generate an equivalent phase-modulated (EPM) signal with an adjustable optical carrier to sideband ratio. The PS-FBG is used as an optical notch filter to remove one sideband of the EPM signal to convert the EPM signal to a single-sideband intensity-modulated signal. At the output of a photodetector, a microwave signal is detected. The entire operation is equivalent to a single passband MPF. The tunability is achieved by tuning the wavelength the optical carrier. The SFDR of the MPF is improved due to the gain enhancement by a partial suppression of the optical carrier. An experiment is performed. A single bandpass MPF with a passband width of 150 MHz and a frequency-tunable range of $\sim 5.5$ GHz with an improved SFDR by 11 dB is demonstrated.
TL;DR: In this paper, a new type of a tunable microwave filtering device with reconfigurable bandpass-filter and bandstop-filter operational modes is reported, which consists of series-cascaded BPF/BSF stages which are formed by two resonating nodes, one non-resonating node (NRN), and two impedance inverters.
Abstract: A new type of a tunable microwave filtering device with reconfigurable bandpass-filter (BPF) and bandstop-filter (BSF) operational modes is reported. It consists of series-cascaded BPF/BSF stages which are formed by two resonating nodes, one non-resonating node (NRN), and two impedance inverters. Each BPF/BSF stage results in two transmission zeros (TZs) that are generated at the natural frequencies of the constituent resonators, whose spectral locations can be reconfigured by tuning the resonating elements. Thus, multi-TZ BPF/BSF responses can be synthesized in the overall circuit which features fully-controllable performances by means of TZ reallocation. The coupling-matrix representation of the proposed frequency-agile BPF/BSF scheme is demonstrated. Moreover, an S-band two-stage prototype based on frequency-reconfigurable evanescent-mode cavity resonators is fabricated to experimentally validate the predicted behavior.
TL;DR: In this article, a quasi-elliptic bandpass filter (QE-BPF) consisting of a pair of shorted stepped-impedance resonators (SSIR) and a dual-mode resonator (DMR) was designed by loading p-i-n diodes at two open ends of DMRs.
Abstract: This later firstly presents a quasi-elliptic bandpass filter (QE-BPF) which consists of a pair of shorted stepped-impedance resonator (SSIR) and a dual-mode resonator (DMR). Then, a 900 MHz switchable bandpass filter (SW-BPF) and a 1250 MHz SW-BPF are designed by loading p-i-n diodes at two open ends of DMR or SSIRs. Finally, a common-T junction constructed by two T-networks is used to combine the above designed 900 and 1250 MHz SW-BPFs to constitute a switchable diplexer. The fabricated QE-BPF, two SW-BPFs and switchable diplexer exhibit wide bandwidth, low insertion loss, sharp passband selectivity, high port isolation and compact size.
TL;DR: In this paper, plate-laminated waveguide filters in diffusion bonding technology for the first time were demonstrated in the integration with a corporate-feed slot array antenna for E-band ultrahigh capacity point-to-point communications.
Abstract: This paper demonstrates plate-laminated waveguide filters in diffusion bonding technology for the first time and shows their uses in the integration with a corporate-feed slot array antenna for E-band ultrahigh capacity point-to-point communications. First, a single-cavity resonator model is studied and the measured high unloaded quality of 2121 at 79.07 GHz indicates its potential in the design of low-loss filters. Consequently, a sixth-order T-shaped cavity bandpass filter that comprises of ten cavity resonators is developed. It exhibits insertion losses of 3.4 and 3.3 dB at 78.5 GHz at two output ports, a 3-dB fractional bandwidth of 20.5%, as well as a small in-band amplitude/phase difference. Then, a fourth-order bandstop filter based on a band-rejection element is presented. It provides a high rejection level of 55 dB at 78.5 GHz and insertion losses of 0.44 and 0.28 dB at 73.5 and 83.5 GHz. The architectures of the proposed filters show attractive compatibility properties for integration. Finally, the proposed filters are fully integrated into a corporate-feed circuit of a $16 \times 16$ -element slot array antenna without an interconnection circuit. With the seamless integration, the proposed building blocks demonstrate well-preserved high efficiency (only a low loss is introduced by the filters) and unchanged radiation characteristic (low sidelobe level, low cross polarization, and high directivity) in the designed passband, as well as specified bandstop performance.
TL;DR: This Letter presents a new narrowband multispectral tunable filter with high throughput over a wide dynamic range composed from a wideband large dynamic range liquid crystal Tunable filter combined with a multiple narrowbands spectral filter made of two stacks of photonic crystals and cavity layer in between.
Abstract: Multispectral tunable filters with high performance are desirable components in various biomedical and industrial applications. In this Letter, we present a new narrowband multispectral tunable filter with high throughput over a wide dynamic range. It is composed from a wideband large dynamic range liquid crystal tunable filter combined with a multiple narrowbands spectral filter made of two stacks of photonic crystals and cavity layer in between. The filter tunes between nine spectral bands covering the range 450–1000 nm with bandwidth 80%.
TL;DR: This work achieves a square-shaped, 20-dB extinction RF photonic filter over a tunable bandwidth of up to 1 GHz with a central frequency tuning range of 16 GHz using a low SBS loss of ~3 dB.
Abstract: In the microwave domain, signal interference bandstop filters with high extinction and wide stopbands are achieved through destructive interference of two signals. Implementation of this filtering concept using RF photonics will lead to unique filters with high performance, enhanced tuning range and reconfigurability. Here we demonstrate an RF photonic signal interference filter, achieved through the combination of precise synthesis of stimulated Brillouin scattering (SBS) loss with advanced phase and amplitude tailoring of RF modulation sidebands. We achieve a square-shaped, 20-dB extinction RF photonic filter over a tunable bandwidth of up to 1 GHz with a central frequency tuning range of 16 GHz using a low SBS loss of ~3 dB. Wideband destructive interference in this novel filter leads to the decoupling of the filter suppression from its bandwidth and shape factor. This allows the creation of a filter with all-optimized qualities.
TL;DR: In this article, a band-pass step impedance filter based on high and low dielectric constant sections has been realized on substrate integrated waveguide (SIW) technology, where the implementation of the impedance inverters has been carried out by means of waveguide sections of lower permittivity.
Abstract: The design and fabrication of a band-pass step impedance filter based on high and low dielectric constant sections has been realized on substrate integrated waveguide (SIW) technology. The overall process includes the design of the ideal band-pass prototype filter, where the implementation of the impedance inverters has been carried out by means of waveguide sections of lower permittivity. This can be practically achieved by implementing arrays of air holes along the waveguide. Several SIW structures with and without arrays of air holes have been simulated and fabricated in order to experimentally evaluate their relative permittivity. Additionally, the equivalent filter in SIW technology has been designed and optimized. Finally, a prototype of the designed filter has been fabricated and measured, showing a good agreement between measurements and simulations, which demonstrates the validity of the proposed design approach.
TL;DR: In this paper, a full-band (from the L-band to the W-band) all-optical RF receiver based on the Si3N4 microring filter is proposed and experimentally demonstrated.
Abstract: Ultra-broadband radiofrequency (RF) receivers are required in higher frequency-band wireless communications, radar communications or multi-band applications in radio telescopes. Such ultra-broadband receivers are inherently difficult to establish with electronics because of limits in the bandwidth of the devices. Photonic means of RF photonic receivers/frontends can overcome the bandwidth limitation in electrical receivers. One aspect that should be considered is the precise signal processing in the optical domain. Here, a full-band (from the L-band to the W-band) all-optical RF receiver based on the Si3N4 microring filter is proposed and experimentally demonstrated. The resolution and processing range of the filter are lower than 420 MHz and larger than 112.9 GHz (FSR larger than 225.78 GHz), respectively, and the out-band suppression of this filter is greater than 40 dB. The center frequency of the filter can be altered for more than one FSR by tuning the phase-shifter on top of the ring. The performance of the full-band all-optical RF-receiver has been discussed, and the spurious free dynamic range of the receiver from the L-band to the Ka-band (limited by the bandwidth of the modulator in our experiment) has been measured to be larger than 111.6 dB·Hz2/3.