High-performance Bandpass Filter Research Articles

High-performance plasmonic mid-infrared bandpass filters by inverse design.

Plasmonic spectral filters composed of periodic nanostructured metal films offer novel opportunities for the development of multispectral imaging technologies in the mid-infrared region. However, traditional plasmonic filters, which typically feature simplistic structures such as nanoholes or nanorings, are constrained by a narrow bandpass and significant crosstalk, leading to limited practical performance. Filters designed using inverse techniques allow a substantial degree of freedom in creating intricate structures that align with desired spectral characteristics, including a quasi-square spectral profile, high transmission, wide full width at half maximum, and reduced crosstalk. In this study, we have utilized an inverse design algorithm to engineer high-performance bandpass filters for the mid-infrared range, achieving an average transmittance exceeding 80% within the bandpass window and below 10% in the stop band, which is comparable to that of commercial multilayer Bragg filters. Nanofabrication processes were employed to transfer the designed pattern into the gold film on ZnS substrate that is transparent in the mid-infrared range. The resulting filters exhibit spectral performance analogous to that of the inversely designed models, making them suitable for direct integration with mid-infrared photodetector arrays in multispectral imaging systems.

Combinatorial protein dimerization enables precise multi-input synthetic computations

Bacterial transcription factors (TFs) with helix-turn-helix (HTH) DNA-binding domains have been widely explored to build orthogonal transcriptional regulation systems in mammalian cells. Here we capitalize on the modular structure of these proteins to build a framework for multi-input logic gates relying on serial combinations of inducible protein–protein interactions. We found that for some TFs, their HTH domain alone is sufficient for DNA binding. By fusing the HTH domain to TFs, we established dimerization dependent rather than DNA-binding-dependent activation. This enabled us to convert gene switches from OFF-type into more widely applicable ON-type systems and to create mammalian gene switches responsive to new inducers. By combining both OFF and ON modes of action, we built a compact, high-performance bandpass filter. Furthermore, we were able to show cytosolic and extracellular dimerization. Cascading up to five pairwise fusion proteins yielded robust multi-input AND logic gates. Combinations of different pairwise fusion proteins afforded a variety of 4-input 1-output AND and OR logic gate configurations.

High performance bandpass filters using printed circuit board packaging technique

In this paper, two compact filters with high selectivity and wideband harmonic suppression are proposed, which use printed circuit board packaging technique. The filters are designed based on the complementary split-ring resonators (CSRRs) and short-circuit centered stepped impedance resonator (SCSIR). High selectivity and wideband harmonic suppression are achieved by controlling the transmission zeros. The center frequency and transmission zeros near the passband can be controlled independently by adjusting the parameters of the CSRR and the SCSIR, respectively. Two bandpass filters are designed with the typical coupling matrix theory. The measured insertion loss is within 2 dB for the two bandpass filters. The transition band from the cut-off frequency to 40 dB attenuation is only 0.12 GHz.

Large aperture, highly uniform narrow bandpass Fabry-Perot filter using photosensitive As2S3 thin films.

We present a thorough study of the use of As2S3 thin films for the fabrication of high-performance bandpass filters. We show that these layers can be included inside a multilayer Fabry-Perot structure in order to produce large-aperture narrow bandpass filters. These layers can also exhibit a large local refractive index change up to 0.1 when they are exposed to actinic radiation at 470nm. Kinetics of photosensitivity are presented. We show that these effects can then be implemented to locally modify the spectral performance of a Fabry-Perot filter after deposition. Highly uniform 65×60 mm2 filters with a 4nm bandpass at 800nm and ±0.1% fluctuations of the central wavelength are demonstrated using this technique.

Design of wide band-pass substrate integrated waveguide (SIW) filters based on stepped impedances

A full-wave design technique of n-order Chebyshev stepped impedance band-pass filters in substrate integrated waveguide (SIW) is presented for the first time. The structure of the filter is based on including elliptic patterns etched on the SIW top surface to synthesize Chebyshev transfer functions. The band-pass response is obtained from the high-pass characteristic of the SIW line together with the behavior of the elliptic patterns, which implement the impedance inverters needed to control an upper cut-off frequency in the response of the filter. The synthesis technique is applied to the design of a sixth-order Chebyshev stepped impedance band-pass SIW filter. It is shown that the use of elliptic patterns instead of circular patterns can increase the spurious free range of the filter. In addition, when exponential microstrip-to-SIW transitions are integrated into the design process, a reduction in size and improvement in return loss are achieved, as compared to a base-line filter (sixth-order Chebyshev stepped impedance band-pass filter) designed with transitions separately. Electromagnetic (EM) simulation and measurements results have shown the effectiveness of the proposed design technique to carry out high-performance band-pass filters in SIW technology.

High‐performance bandpass filter using HTCC stepped‐impedance resonators

Here, a novel rectangular bar stripline stepped-impedance resonator (SIR) using the multilayer high-temperature co-fired ceramic (HTCC) technology is constructed for designing a high-performance bandpass filter (BPF) with enhanced design flexibility. The properties of the HTCC SIR are investigated, so that its quality factor ( Q u ) can be improved. In the design process of comb-stripline filter, two transmission zeros (TZs) on both sides of the passband can be synthesised using the equivalent model for enhancing the passband selectivity. Thus, the resultant filter produced by the high dielectric constant material has several advantages, such as low passband loss, high selectivity, and compact size, which are verified by the simulation and measurement. In the demonstration of the fourth-order BPF centred at 2.25 GHz, two TZs are located at 2.05 and 2.54 GHz, showcasing a sharp roll-off. The insertion loss is <;1.8 dB in the passband. The BPF has a smaller size, when compared with the counterparts using other technologies. The occupied area of the BPF is 4.84 × 6.96 mm 2 .

A novel compact and high performance bandpass filter based on SIW and CMRC technique

Based on the substrate integrated waveguide (SIW) and compact microstrip resonant cell (CMRC) technique, a compact and high performance planar bandpass filter (BPF) is proposed in this paper. The SIW cavity, which has the advantages of high quality and low insertion loss, provides a highpass characteristic. The CMRC structure etched on the top metal plane of the SIW cavity behaves as a lowpass filter, and it can also effectively reduce the dimension of the filter. In order to improve the out-of-band rejection and sharpen skirt selectivity, the open circuit lines at the input and output ports of the filter are introduced. Moreover, the bandwidth and center frequency of the proposed filter can be flexibly tuned by adjusting the cutoff frequencies of the SIW and CMRC separately. As a verification, a representative BPF having a center frequency of 4.54GHz and a 3dB bandwidth of 1.39GHz is designed, fabricated, and experimentally evaluated. The simulated and measured results are in good agreement.

Realization of high-performance bandpass filter by impedance-mirroring

Ideal bandpass filters must have sharp roll-off and high transmission over a target pass band simultaneoulsy, but it is still difficult to make such filters of a reasnoable size. To achieve such performance, we propose a novel finite phononic crystal filter made of impedance-mirrored elements each of which constists of two layers having different impedances. For broad bandpass filtering, one of the two layers is selected to be one eighth wavelength long at the center frequency of the passband and the other layer, one quarter wavelength long with a matched impedance. For narrow bandpass filtering, the broad bandpass filter is slightly modified in such a way that the concept of the impedance-mirroring is applied globally over the finite periodic structure filter, not within each unit cell. To check the performance of the proposed filters, experiments using torsional elastic waves in a rod were conducted.

Substrate Integrated Waveguide (SIW) With Koch Fractal Electromagnetic Bandgap Structures (KFEBG) for Bandpass Filter Design

High-performance bandpass filters (BPFs) based on substrate integrated waveguide (SIW) and half mode SIW (HMSIW) with Koch fractal electromagnetic bandgap (KFEBG) patterns etched on the waveguide surface are proposed. These BPFs are designed using a new methodology. The BPF responses are improved by applying a chirped and tapered technique to the KFEBG patterns which exhibit a radius-to-period ratio r/a ≥ 0.5. Simulation results and experimental verification are presented. Good values for insertion losses and stopband rejection are achieved.

Mode-coupling mechanisms of resonant transmission filters.

We study theoretically modal properties and parametric dependence of guided-mode resonance bandpass filters operating in the mid- and near-infrared spectral domains. We investigate three different device architectures consisting of single, double, and triple layers based on all-transparent dielectric and semiconductor thin films. The three device classes show high-performance bandpass filter profiles with broad, flat low-transmission sidebands accommodating sharp transmission peaks with their efficiencies approaching 100% with appropriate blending of multiple guided modes. We present three modal coupling configurations forming complex mixtures of two or three distinct leaky modes coupling at different evanescent diffraction orders. These modal compositions produce various widths of sidebands ranging from ~30 nm to ~2100 nm and transmission peak-linewidths ranging from ~1 pm to ~10 nm. Our modal analysis demonstrates key attributes of subwavelength periodic thin-film structures in multiple-modal blending to achieve desired transmission spectra. The design principle is applicable to various optical elements such as high-power optical filters, low-noise label-free biochemical sensor templates, and high-density display pixels.

Compact and high-performance bandpass filter and diplexer based on SCMRC-loaded SIR

Bandpass filter (BPF) and diplexer, which are required to be compact size and high performance, are widely used in modern wireless communication systems. In this article, novel BPF and diplexer are designed using the proposed resonator called spiral compact microstrip resonator cell (SCMRC)-loaded stepped-impedance resonator (SIR). The SCMRC-loaded SIR is proposed using the slow-wave structure SCMRC to replace the low-impedance section of the conventional SIR. Compared with the conventional SIR, the new SCMRC-loaded SIR has a compacter size and can generate a transmission zero above its fundamental resonant frequency. As examples, a BPF with the central frequency at f 0 = 1 GHz and a diplexer operating at 0.9/1.57 GHz are designed and fabricated. The fabricated BPF occupies a compact size of 0.07 λ 0 × 0.035 λ 0 and has a −60 dB rejection level wide stopband from 1.2 f 0 to 3.8 f 0. The fabricated diplexer occupies a compact size of 0.076 λ 0 × 0.128 λ 0 and has an up to −50 dB output isolation. Good agreement can be observed between the simulations and the measurements.

Embedded Wafer Level Packaging for 77-GHz Automotive Radar Front-End With Through Silicon Via and its 3-D Integration

In this paper, a 77-GHz automotive radar sensor transceiver front-end module is packaged with a novel embedded wafer level packaging (EMWLP) technology. The bare transceiver die and the pre-fabricated through silicon via (TSV) chip are reconfigured to form a molded wafer through a compression molding process. The TSVs built on a high resistivity wafer serve as vertical interconnects, carrying radio-frequency (RF) signals up to 77 GHz. The RF path transitions are carefully designed to minimize the insertion loss in the frequency band of concern. The proposed EMWLP module also provides a platform to design integrated passive components. A substrate-integrated waveguide resonator is implemented with TSVs as the via fences, and it is later used to design a second-order 77-GHz high performance bandpass filter. Both the resonator and the bandpass filter are fabricated and measured, and the measurement results match with the simulation results very well.

Novel slotted stepped-impedance resonator and its application to compact and high performance bandpass filter and diplexer design

By etching slots in the low-impedance section of the conventional stepped-impedance resonator, a novel slotted stepped-impedance resonator (SSIR) is proposed. As two examples, a fourth-order bandpass filter (BPF) operating at 1 GHz with a size of 0.078 λg × 0.062 λg and a miniaturized diplexer operating at 0.9/1.57 GHz with a size of 0.054 λ0 × 0.086 λ0 are designed based on the proposed SSIR. The fabricated BPF exhibits a high selectivity and a wide −30 dB rejection upper stopband from 1.13 f0 to 6.52 f0, while the fabricated diplexer has up to −60 dB output isolation. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.

High-Order Infinite Impulse Response Microwave Photonic Filters

Two new high-order infinite impulse response microwave photonic filters, which have multiple poles and zeros in the transfer characteristic, are presented. They are based on either the wavelength division multiplexing technique with a single infinite impulse response delay line structure or a single laser with multiple infinite impulse response delay line structures. A wavelength converter is used to increase the filter order without the coherent interference problem. A high-resolution and high-performance bandpass filter response can be realized. Experimental results are presented that demonstrate high-resolution bandpass filter responses with robust operation, and high stopband rejection level and high skirt selectivity.

Compact and High Performance Bandpass Filter Based on an Improved Hybrid Resonator Using Beeline Compact Microstrip Resonator Cell (BCMRC)

In this paper, a compact microstrip bandpass filter is presented by using a proposed improved hybrid resonator. Without requiring the cross-coupling and the source-load coupling, the new filter has a transmission zero on the upper stopband to provide a high selectivity. The fabricated filter is designed at f 0 = 1 GHz and has a compact size of 0.112λg×0.057λg. Good agreement is observed between the measurements and simulations. The measured results show that the new filter has a wide −60 dB rejection upper stopband from 1.24f 0 to 4.05f 0. In addition, a −20 dB rejection ultra-wide upper stopband is measured from 1.08f 0 to 15.38f 0. The new filter can be fabricated using the standard printed-circuit-board (PCB) process and has a planar topology, which is easily integrated with the modern wireless communication system.

A High Performance Bandpass Filter with a Wide and Deep Stopband by Using Square Stepped Impedance Resonators

In this paper, a microstrip bandpass filter with a wide and deep stopband by using the modified stepped-impedance resonator (SIR) was designed and implemented. The modified SIR is formed by properly folding the conventional SIR to be a square open-loop SIR. By analyzing the admittance of the even and odd mode, the transmission zero of the modified SIR can be easily found, thus having a wide and deep stopband simultaneously. Bandpass filter (BPF) can have high performances with a wide and deep stopband as well as good selectivity by using the proposed SIR, compared to the conventional SIR. A filter example centered at f 0 of 1.26 GHz has been implemented to verify the design concept. The results showed that the |S 21| was greater than 65 dB at the spurious response of 2f 0 and a wide stopband with a rejection level over 50 dB is extended from 1.5f 0 to 3.5f 0. Moreover, experimental results have a good agreement with the simulated results.

Design and implementation of a high‐performance V‐band CMOS bandpass filter

AbstractIn this article, we demonstrate a low‐insertion‐loss V‐band (50–75 GHz) bandpass filter with two finite transmission zeros by standard 0.13 μm CMOS technology. The proposed filter architecture has the following feature: the low‐frequency transmission‐zero and the high‐frequency transmission‐zero can be tuned by the series‐feedback capacitor Cs and the parallel‐feedback capacitor Cp, respectively. Besides, low‐insertion‐loss is achieved by adopting thick microstrip‐line (MSL) with optimized ground‐plane pattern as the needed inductors to minimize the metal and substrate loss. This filter achieved insertion‐loss (1/S21) lower than 3 dB over the frequency range of 52.2–76.7 GHz, input return loss (S11) better than −10 dB over the frequency range of 50.2–80.6 GHz, and output return loss (S22) better than −10 dB over the frequency range of 50.2–77.3 GHz. The minimum insertion‐loss was 2.18 dB at 63.5 GHz, an excellent result for a V‐band CMOS bandpass filter. The chip area was only 0.466 × 0.307 mm2, i.e., 0.143 mm2, excluding the test pads. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 309–316, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24935

Tunable photonic bandpass filter with high-frequency response performance

A continuously tunable RF/microwave photonic bandpass filter that simultaneously achieves high skirt selectivity and high stopband attenuation is presented. It is based on controlling the signal polarisation state in a reflective amplified recirculating delay line loop with a polariser at the output. A technique to overcome the phase noise limitation in the structure is also presented. Experimental results demonstrate continuous tuning of the high-performance photonic bandpass filter and a continuously tunable photonic bandpass filter with a low-noise performance.

Limits of performance of mechanical band-pass filters used in energy scavenging

In this note, the performance of mechanical band-pass filters to be used in energy scavengers is studied. Such a filter consists of an ensemble of cantilever beams where at the tip of each beam a mass, known as the proof mass, is mounted. Two questions are raised regarding the performance of the filter: (i) What is the best possible performance of the filter? (ii) How can a filter with such a performance be designed? In answering these questions, the limits of performance of the filter are determined. Knowledge of such limits leads to a systematic procedure for determining dimensions of the beams and masses of the proof masses of high-performance band-pass filters.

High performance bandpass filters based on electric arc-induced -shifted long-period fibre gratings

The inscription of π-shifted long-period fibre gratings with the electric-arc technique is presented. By exploiting the flexibility of this technique, the first bandpass filters having lateral rejected bands with isolation ≥20 dB have been realised. Also fabricated are high performance bandpass filters with larger bandwidths, this being achieved by introducing two π-phase-shifts into the grating.