Dual Bandpass Filter Research Articles

Miniaturized millimeter-wave dual-band band-pass on-chip filter in 0.13-μm SiGe BiCMOS

A design approach for a compact on-chip millimeter wave (mm-wave) dual-passband filter employing hybrid electromagnetic coupling (HEMC) and tunable transmission zeros (TZs) is presented in a 0.13-μm SiGe BiCMOS technology. A dual-mode double-layer series folded resonator with a quarter wavelength has been designed, which reduces the chip area by approximately 40 % compared to a single-mode planar quarter resonator. Additionally, TZs controlled by HEMC are introduced to enhance filter selectivity. A dual-passband filter operating in the W/F-band was realized in the 0.13-μm SiGe (Bi)-CMOS technology, with corresponding fractional bandwidths (FBW) of 15.1 % and 16.2 %, at 94/120 GHz respectively, and the average roll off rate of the filter is greater than 2 dB/GHz. The measured results demonstrate insertion losses below 5.7 dB in both passbands and the compact chip dimension is 626 × 813 μm2. When this chip can be placed after the low-noise amplifier in a receiver, the insertion loss has little negative impact on system performance. To our knowledge, this is the first time a 94/120 GHz dual-band BPF in Bi-CMOS technology has been implemented in such a small size. This study presents an alternative design methodology for miniaturizing and streamlining the structure of millimeter-wave dual-passband filters in the SiGe process.

A low-cost dual bandpass planar filter for WiMAX and mobile communications

This study proposes a new design of low-cost dual-bandpass filter for worldwide interoperability and microwave access (WiMAX) band at <br /> 3.50 GHz and mobile communications band at 1.19 GHz. A high pass filter and a stopband filter make up the new dual-bandpass filter structure. Different theoretical studies were carried out for the design of the proposed filter. This filter’s base is a RO5880 substrate with a dielectric permittivity constant of 2.2, loss tangent of 0.0009 and 1.6 mm thickness. High mashing density was used to validate the various simulated structures while accounting for two numerical methods: the moment technique and the finite integration method. The final circuit's overall dimensions are 60×178,3 mm<sup>2</sup>.

Design and Manufacturing of Filter Sets for Dual-Color Synchronous Gene Sequencing

Gene sequencing is an important means for modern life sciences research and clinical diagnosis. In recent years, dual-color synchronous gene sequencing has developed rapidly due to its excellent properties such as high throughput, fast speed, miniaturization, and low cost. In this paper, a type of dual-color synchronous gene sequencing optical path structure, which is based on the fluorescence-detection principle, was designed. FAM and TAMRA were selected as the fluorophores, which corresponded to excitation light sources with 488 nm laser and 543 nm laser, respectively. Combining the optical system and fluorophores, we designed the parameters of the filter sets, including the details of design methods for dual-bandpass filters and dual-notch dichromic mirrors. Moreover, these filters were successfully manufactured by ion-assisted deposition and magnetron-sputtering methods with extreme precision. The satisfying application effect was demonstrated when these products were applied in customer-desktop medium-throughput gene sequencers.

Miniaturized metallic symmetrical resonator backed CPW inspired dual band filter using Meander line for 5G mm‐wave applications

AbstractAn ultra‐miniaturized symmetrical resonator backed coplanar waveguide based dual band pass filter using Meander line for 5G mm‐wave applications is presented. Meander line CPW structure with ultra miniaturized size was designed, investigated and its equivalent circuit was extracted using theoretical and experimental results to explore basic RF characteristics. The resonator at the back side of the substrate is symmetrical in both horizontal and vertical plane. This resonator is electrically coupled with the Meander line structure in the conducting plane. Symmetrical resonator structure coupled with open stubs on both sides on ground plane and Meander line structure with uniform spacing implemented at the conducting layer constitutes the metallic backed Co‐Planar waveguide based dual band filter. By using Meander line, the overall size of the communication devices has been reduced in large scale. The combination of symmetrical resonator and Meander line structure produces the overall bandwidth from (1 to 30) GHz. 5G mm‐wave filter operates in two bands; Band I operates from (1 to 14.2) GHz with insertion loss −1.8 dB and return loss −34 dB with fractional bandwidth of 73.6%; Band II operates from (16.2 to 30) GHz with insertion loss −1.2 dB, return loss −30 dB and fractional bandwidth of 59.7%. The overall filter circuit geometry is (5 × 5 × 1.6) mm and in terms of wavelength: (0.52 × 0.52) λg.

Design of dual-mode resonators based on laterally coupled alternating thickness (LCAT) modes for WiFi 2.4G and n77 dual-passband filter

This paper explores a dual-mode resonator that uses laterally coupled alternating thickness (LCAT) modes, and a dual-passband filter for WiFi 2.4G and n77 bands is constructed. The resonator's frequency can be adjusted by the electrode thickness, period and piezoelectric film thickness, and their effects on the quality factor (Q) values and effective electromechanical coupling coefficient (k2eff) were analyzed. In addition, the impact of Sc-doped concentration on resonators' performance was investigated, and the AlSc0.35N-based resonators exhibited both high Q and k2eff values. Furthermore, two resonant modes were effectively excited by setting two working regions. Adding an acoustic blocking groove reduces mutual acoustic energy leakage, increasing Q values for target modes and suppressing spurious signals. The dual-mode resonator’ structure were further optimized to ensure that both modes have similar high performance. Ultimately, this work constructs a dual passband filter with center frequencies of 2.49 and 3.54 GHz with 75 and 132 MHz bandwidths respectively, and achieves over 60 dB out-of-band rejection.

Accurate Synthesis of Input-Reflectionless Dual-Passband Filter

This article presents a rigorous synthesis method for input-reflectionless dual-passband filters. As this work provides closed-form formulas for the normalized coupling values of both the filtering and matching sections for producing zero reflection at all frequencies, they can be obtained instantly without using time-consuming trial-and-error methods. As the formulas are generalized for a case with arbitrary cutoff frequencies in the normalized frequency domain, an input-reflectionless filter with two passbands separated arbitrarily can readily be synthesized and designed. For demonstration, the normalized coupling values obtained by using the proposed synthesis method have been applied to the design of a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ka$ </tex-math></inline-formula> -band waveguide input-reflectionless dual-passband filter. The measurement shows a reflectionless feature over the entire WR-42 band which verifies our synthesis and design approaches.

Dual-band filter design based on hourglass-shaped spoof surface plasmon polaritons and interdigital capacitor structure

In this paper, a dual passband filter with spoof surface plasmon polaritons (SSPPs) and interdigital capacitance structure loaded on a coplanar waveguide (CPW) is proposed. First, the hourglass-shaped SSPP unit-cell structure and the interdigital capacitor structure are introduced on the coplanar waveguide transmission line to obtain high fractional bandwidth and low insertion loss passband characteristics. Then, a dual passband filter is formed by loading the interdigital capacitor loop resonator to excite the trapped waves. The simulation results show that the proposed dual passband filter has excellent upper sideband rejection and dual passband filtering performance. The fractional bandwidths of the two passbands of the design are 46.8% (1.49–2.40 GHz) and 15.1% (2.98–3.63 GHz), respectively, which can achieve more than –40 dB rejection in a range of 4.77–7.48 GHz. The upper cutoff frequency and lower cutoff frequency of the two passbands can be independently regulated by changing the structural parameters of the proposed filter. In order to gain a more in-depth understanding of the operating principle of the dual passband filter, the corresponding dispersion curves and electric field distribution, LC equivalent circuit analysis are given. Finally, the prototype of the designed filter is fabricated according to the optimized parameter values. The experimental results are in good agreement with the simulation ones, indicating that the proposed dual-passband filter is of great importance in implementing microwave integrated circuits .

Dual two-color method: A new concept of ultra-wide temperature range thermography (200-3600 °C) for ITER divertor infrared thermography.

A new temperature measurement method-the dual two-color method-was developed to accurately measure the temperature over an ultra-wide temperature range (200-3600 °C) for ITER divertor infrared thermography. This novel method introduces a third wavelength filter to the conventional two-color method by replacing the shorter single wavelength bandpass filter with a customized dual-bandpass filter having two transmission bands, without having to add a third infrared camera. The dominant wavelength band of the total radiance through the dual-band filter changes automatically as the temperature increases and, consequently, either the shorter or longer wavelength band of the dual-bandpass filter is used to establish the two-color combination at both low and high temperatures. The dual two-color method increased the acceptable measurement error of the two-color radiance ratio for the temperature measurement requirement of the ITER divertor infrared thermography to 9.45% from that of 4.3% when using the conventional two-color method.

Compact Dual Bandpass Filter Using Dual-Split Ring Resonator for 5G Upper Microwave Flexible Use Services

A novel, compact dual bandpass filter design is proposed for 5G upper microwave flexible use services. To realize the proposed design, a dual split-ring resonator structure coupled to the microstrip transmission line is used. The output responses have been validated using vector network analyzer N5222A. The measured filter records a frequency range of 23.8 GHz–25.98 GHz for the first passband and 28.05 GHz–28.7 GHz for the second band, with fractional bandwidths of 8.8% and 2.2%, respectively. The minimum insertion loss is observed to be 4.2 dB using microstrip technology, even at higher frequencies. The proposed design occupies the area of 0.4 λg×0.27 λg, where λg is guided wavelength at the lower band central frequency. Simulated and measured results are approximately compatible with each other. The proposed design is useful for fixed satellite service earth stations, terrestrial wireless operations, and 5G mobile communications applications.

Dual Pass Band Filter using Quad Stub Loaded Uniform Impedance Resonator

A low loss, highly selective and miniaturized dual pass band filter for the wireless (WiMAX, WLAN) application is proposed in this paper. The filter is designed with Multimode resonators, constructed with Uniform Impedance Resonator (UIR) and multiple open stubs. Two different coupling schemes (electronic and magnetic) are observed for the said dual pass bands. A detail analysis about the dimension of the resonators, resonating conditions and frequency calculations are presented in this paper. The dual pass bands are achieved at 3.45 GHz and 5.4 GHz with minimum pass band insertion loss (|IL|) 0.1 and 0.18 dB and the pass band Fractional Band widths (FBW) 4% and 8% respectively. With proper optimizations, Transmission Zeros (TZ) are achieved on both sides of the dual pass bands and the spurious pass band are kept around -20dB level and hence good selectivity is achieved. The overall size of the filter is optimized for the best possible results in terms of Insertion Loss, Return Loss and selectivity, is found to be (24.2 x 21)mm = (0.28 x 0.24)λg = 0.06 λg2.

Balanced quasi-elliptic-type dual-passband filters using planar transversal coupled-line sections and their digital modeling

AbstractA class of balanced dual-band bandpass filters (BPFs) with planar transversal-signal-interference coupled-line sections is reported. In their building balanced dual-band BPF stage under differential-mode excitation, a second-order quasi-elliptic-type dual-band bandpass filtering transfer function is obtained. Specifically, from the transversal interaction among their two open-ended and virtually-short-ended half-wavelength coupled-line paths, sharp-rejection differential-mode dual passbands with several out-of-band transmission zeros at both sides are realized. To attain high common-mode suppression levels within the differential-mode passbands, two open-ended line segments are connected at the symmetry plane of the devised balanced dual-band BPF stage. Moreover, higher-order schemes based on in-series-cascaded multi-stage designs to further increase differential-mode selectivity and in-band common-mode rejection are illustrated. The operational principles and parametric-analysis design rules of the engineered transversal-coupled-line-based balanced dual-band BPF approach are detailed. Additionally, for a rigorous interpretation of their zero/pole characteristics, a digital-modeling framework is applied to them to connect RF balanced filters with their discrete-time versions. For practical-validation purposes, a microstrip prototype of two-stage/fourth-order balanced dual-band BPF is built and tested. It exhibits measured differential-mode dual passbands with center frequencies of 1.464 GHz and 2.294 GHz, 3-dB fractional bandwidths of 8.74% and 9.68%, and in-band common-mode rejection levels above 23.16 dB and 31.36 dB, respectively.

Tradeoffs With RGB-IR Image Sensors

Cameras with RGB-infrared (IR) image sensors are advantageous for applications that can benefit from simultaneous capture of color and near-IR (NIR) images. High quantum efficiency (QE) in NIR is desired for RGB-IR image sensors because it allows to reduce power of NIR illuminants, however, there is a tradeoff. As imaging with RGB-IR sensors is often done with visible/NIR dual bandpass filters, high NIR signal can lower the dynamic-range and the signal-to-noise ratio (SNR) of the color images. This work studies the effect of the NIR signal on the dynamic-range and the SNR of color and NIR images of RGB-IR image sensors. It presents a model that allows to evaluate these metrics using image sensor, camera, and scene parameters. The model is applied for the case of varied illuminant NIR content and for the case of varied pixel QE in NIR. Both cases are evaluated theoretically and experimentally, and experimental results are in good agreement with simulations.

Dual-Band Pass Filter with Wide Band-Frequency Rejection

A Dual band Filter block has been highly attention due to its highly importance in wireless communication systems. High frequency level normally companies with the performance of filter block. The use of both low-pass or band-stop filter and the step-impedance lines methods to reduce the spurious characteristics of the filter are not a practical solution since that adds more complexity and large in size. The proposed microstrip filter was utilized for Industrial Scientific and Medical (ISM) applications (2.45 GHz) with -25 dB with twice transmission zeroes as a first band while the second band of (3.5-8 GHz) for LTE and wireless LAN applications with return loss up-to -15 dB. (CST) Computer Simulation Technology was used to simulate the declared structure. The dual band, mode simulation results have been extracted and also compared with the literature that get closed to each other. So that, the computer aided design gives a good pointer to adopt an extracting result that have been obtained using the aforementioned simulator.

A Compact Wide Stopband Band Pass SIW Filter For K-Band Applications

Direct coupled filters have narrow stopband due to higher order modes passband. A compact dual layer band pass filter is proposed with wide stop band. The proposed filter provides the return loss of 16.87db and insertion loss of 2.5dB at the passband frequency 20.9 GHz. The filter size is half of the conventional direct coupled filters. The stop band covers up to 40 GHz with insertion loss below 35dB. The filter has no slot which makes it immune to the EMI/EMC problems.

A Miniaturized Frequency Selective Rasorber With Independently Regulated Selective Dual-Transmission Response

In this letter, a miniaturized-element dual-polarized frequency selective rasorber (FSR) with independently regulated dual-transmission response has been presented. The proposed FSR is made of two cascaded layers separated by an air spacer, where the top lossy layer provides wideband absorption along with in-band transmission and the bottom lossless layer exhibits a dual bandpass filter. The novelty of the proposed design lies in the use of lumped capacitors in the top layer to realize the independently controlled highly selective transmission frequencies as well as attain a miniaturized unit cell topology (having dimensions of 0.08 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> × 0.08 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> , λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> being the lowest operating frequency). In addition, convoluted slot geometries are patterned in the bottom layer to obtain the transmission bands appearing at the same frequencies as that of the top layer. The proposed structure has an operating range of 1.87–7.97 GHz, whereas two distinct transmission responses are located at 3.52 and 5 GHz having insertion losses of 1.2 and 0.82 dB, respectively. Furthermore, the geometry exhibits an angularly stable performance upto 40° for both TE and TM polarizations. A prototype of the proposed FSR was fabricated and measured to validate the simulated responses under normal incidence.

Design and Optimization of the Dual-Mode Lamb Wave Resonator and Dual-Passband Filter.

Radio frequency (RF) filters with multiple passbands can meet the needs of miniaturization and integration for 5G communications. This paper reports a dual-mode Lamb wave resonator (DLWR) and a dual-passband filter based on DLWRs. The DLWR consists of a piezoelectric film and two interdigital electrode (IDT) arrays with different thicknesses, which leads to the coexistence of two main modes in the resonator. The resonance frequencies of the two modes can be adjusted separately by changing the thicknesses of the IDTs, which greatly satisfies the requirements of the dual-passband filter. Four DLWRs with different electrode configurations are designed, and the influences of the periodic length and thicknesses of the IDTs on the performance of the DLWR are studied. When the thickness of the piezoelectric layer is 0.75 μm and the two thicknesses of the IDTs are 0.1 μm and 0.3 μm, the resonance frequency of the second main mode is 1.27 GHz higher than the resonance frequency of the first main mode in the DLWR. Furthermore, a dual-passband filter based on the proposed DLWRs is demonstrated with an insertion loss less than 1 dB and a band rejection of about 15 dB. Moreover, two passbands at 2.45 GHz and 3.88 GHz with bandwidths of 66 MHz and 112 MHz, respectively, are achieved. The presented DLWR shows a potential application that can be used to obtain RF filters with adjustable dual passbands.

Non-Uniform Pitch Helical Resonators for Dual-Passband Filter Design

This paper presents a study of a non-uniform pitch helical resonator (NPHR) structure and the coupling mechanisms to design dual-passband filters. The previous research analyzes NPHR as a type of step impedance resonator (SIR), however, it does not give analytical equations or prediction for the dual-resonance characteristics of the NPHR structure discussed in this paper. Consequently, a circuit model is proposed to analyze the dual-resonance characteristics of NPHRs. Analytical equations are derived, showing that the frequency ratio of a dual-band NPHR can be determined by the ratio of turns. EM simulation and experimental results have shown good agreement with the circuit analysis. The derived analytical equations from circuit model can be used for fast design of NPHRs. A step-width aperture is proposed to independently control the coupling coefficients at the each band of NPHRs. A third order dual-passband filter has been designed and fabricated. The filter has 3.3% and 3% fractional bandwidths at 789 MHz and 2402 MHz, respectively. The designed prototype filter shows that NPHRs can be utilized to realize compact filters with dual-band characteristics. The filter design can be extended from engineering perspective for application in wireless communication systems.

Design and fabrication of short and middle wavelength infrared dual band-pass filter at cryogenic temperature

Design and fabrication of short and middle wavelength infrared dual band-pass filter at cryogenic temperature

Design of dual-band pass filter with two end-to-ends T-shaped resonator and open ended stubs for wireless LAN applications

Design of dual-band pass filter with two end-to-ends T-shaped resonator and open ended stubs for wireless LAN applications

Optical applications of transition metal ion doped phosphate glasses

The transition metal ion-doped lithium phosphate glasses are prepared with a novel composition by melt quenching method, XRD patterns revealed their characteristic amorphous nature. The structural and physical properties of the prepared glasses are significantly varying with the increased concentration levels of dopant. Optical absorption and transmission spectra of the glass samples are analyzed. The absorption peaks are observed in ultraviolet, visible and infrared regions.The direct and indirect energy band gap values are decreasing while Urbach’s energy values are increasing as the concentration levels of dopants are increasing. The obtained energy band gap values are in the range of semiconductor materials. The optical transmission spectra of these transition metal ion-doped glasses reveal their application as bandpass filters with filtering ability in UV or Visible regions at double and triple wavelengths and hence useful as dual band-pass filters. The glasses with <10 full width half maximum(FWHM) values are useful for narrowband lasers.