Dual Bandpass Filter Research Articles

Design and Analysis of Dual-Mode Double-Ring Resonator for Dual-Band Bandpass Filter Applications

In this paper, two types of miniaturized dual-mode bandpass filters (BPF), a single-ring (SR) resonator, and a double-ring (DR) resonator are developed. By applying the capacitive-coupling technique to a dual-mode ring filter, a technique is proposed to miniaturize the dual-mode double-ring filter. An adjustable dual-band bandpass filter is achieved by developing a ring resonator where the two modes are capacitively coupled. Control of the filter center frequency is determined by the diameter of the ring and by the rings annular width. Filter coupling amount can also be adjusted by disturbance (perturbation) of an open stub attached to the annular disc. Proposed filters explore both single- and double-ring architectures. A single-ring resonator acting as a dual bandpass filter to allow 3.8 GHz and 7.8 GHz single is developed. A double-ring resonator to allow 2.05 GHz and 3.9 GHz signals is also developed. The ring resonators are fabricated on RO-4003 substrate, with relative dielectric constant of 3.38, thickness of 0.8 mm, and dielectric loss tangent of 0.0025. Results indicate the filters can be applied in the communications field.

Dual-band bandpass filter using centrally coupled resonators (CCRs)

In this paper, a compact dual-band bandpass filter using novel centrally coupled resonators (CCRs) is presented. The proposed CCR is composed of a meandered microstrip line with a centrally coupled section and two lumped capacitors, which are loaded at the ends of the coupled lines. Based on the theoretical analysis, a key merit of the proposed resonator is found that both even- and odd-mode resonances can be separately controlled by altering the values of the relative loading capacitors. Benefitting from this feature, a dual-passband filter with two independent operating frequencies can be designed and a sample topology is demonstrated. The measured results exhibit good agreement with the full-wave simulation results, validating the proposed design concept.

Direct Synthesis Technique for Dual-Passband Filters: Superposition Approach

In this brief, a technique is proposed for the synthesis of dual-passband filters. Different from conventional techniques based on low-pass prototype, the technique in this brief can directly synthesize filters in bandpass form. Each passband of the filters can be accurately and separately designed, and then, their characteristic functions are superposed to obtain the final characteristic function for the dual-passband filters to be synthesized. Network matrix derived from this technique is physically meaningful, while coupling matrices derived by conventional techniques can be considered as its low-pass approximation. The proposed technique is simple and fast.

Multi-Band Radar Receiver Design Approach for Minimum Bandpass Sampling

Multi-frequency radars, which are employed in a plurality of emerging applications, exploit the echoes for different bands that come from illuminated targets. A compact multi-function architecture that makes use of direct sampling could be a preferable choice for these new-generation radar systems, with RF front-end design a first step in their development. Here, within the framework of multi-frequency radars, an analytical tool for simultaneously acquiring the signal bands by using the minimum sub-Nyquist sampling frequency is addressed. Although the dual-band radar scenario is exhaustively analyzed, keys to understand the acquisition of more-than-two-band systems are also provided. Moreover, as the core of the associated RF architecture to carry out arbitrary multi-band signal pre-selections, a new class of microwave planar multi-passband filters based on stepped-impedance-line signal-interference concepts is reported. Also, for validation, the construction and testing of a microstrip spectrally-asymmetrical dual-passband filter prototype for a specific example of minimum-sampling dual-frequency radar RF front-end are shown.

Dual-Bandpass Filters With Individually Controllable Passbands

A novel dual-band filter based on split-ring resonators (SRRs) and double-slit complementary SRRs is presented. The size of the filter is small and the two passbands can be individually designed. The basic cell of the filter is presented and analyzed, and then the multistage dual-passband filter is achieved by cascading basic cells. The design graphs for external quality factors of the resonators at input and output stages and the coupling coefficient between the adjacent resonators are constructed. The design graphs are utilized to determine the proper geometric parameters of each filter stage for a given filter specification. As an example, a prototype three-stage Chebyshev filter with a fractional bandwidth (FBW) of 2% at 0.9 GHz and a FBW of 3% at 1.3 GHz is demonstrated. The prototyped filter has an equal ripple of 0.4 dB at both passbands. The measurements of the prototyped filter agree well with the simulation results. The center frequencies and the FBWs of the two passbands of the prototyped filter can be individually designed with more flexibility compared to dual-band filters that utilize resonances of higher order modes. The overall size reduction of the proposed filter can be as high as by a factor of 3 compared to that of edge-coupled microstrip filters.

A dual mode filter with wideband suppression

This paper presents a novel method to suppress the harmonic responses of dual mode bandpass filters. The harmonic suppression is based on discriminating coupling. The coupling coefficient at fundamental resonant frequency can be tuned to desirable value whereas it is approaching to zero at high-order harmonic. The coupling region blocks the high-order harmonic but still allows the transmission of signals at passband frequency. Benefiting from this feature, the high order harmonic can be suppressed without degrading the passband performance. Furthermore, no additional circuit is needed. An example filter is implemented, and experimental results are presented to verify the proposed method.

A Compact Varactor-Tuned Dual-Passband Filter Using Stepped Impedance Resonators

A compact dual-passband varactor-tuned filter using stepped impedance resonators (SIRs) is proposed in this paper. The SIRs with varactors centrally attached are coupled with an input/output transmission line. The structure is realized by dividing the input line from a normal coupling structure into two lines of a dual-finger structure. When the bias voltage is loaded, extra blocking capacitance is needless, which is good for eliminating parasitic and reducing insertion loss. The center frequency of the upper passband can be tuned from 1.18GHz to 1.64GHz by changing the value of the bias voltage across the varactor, and meanwhile the center frequency of the lower passband is fixed at 900 MHz. The measured results show that the proposed filter can provide flexible selectivity and good stopband characteristic. The measured performances are in good agreement with the simulated ones.

A fully integrated programmable dual-band RF filter based on electrically and mechanically coupled CMOS-MEMS resonators

In this paper, a novel fully integrated CMOS-MEMS filter implemented on a commercial CMOS technology is presented. The combination of mechanical and electrical coupling is used to enhance the response of the band pass filter. In particular, a 20 dB shape factor as low as 2 and a 35 dB stopband rejection are achieved. Moreover, the topology of the device allows obtaining a dual-bandpass filter behavior, presenting a tunable bandwidth and a deep notch between bands. Results show a dual-band filter with a 22 dB inner stopband rejection, center frequencies at 27.5 and 27.8 MHz, respectively, and a 0.6% relative bandwidth.

On the Design of a Multiple Pass-band Filter by Frequency Transformation

It is shown that the use of reactance functions for frequency transformation of a normalized low-pass filter (NLPF) to a multiple passband filter (MPBF) is straightforward and simpler than the methods using repeated low-pass to band-pass transformation or a combination of such transformations. The method gives the band edges of the MPBF corresponding to the positive and negative cutoff frequencies of the NLPF unambiguously. The transformation function is found explicitly in terms of the band edges of the MPBF and the NLPF elements are converted to those of the MPBF with ease. Furthermore, the center frequencies of the passbands are also found with ease. Dual and triple passband filters are considered for illustrating the use of the method.

Miniaturised multi-band substrate integrated waveguide filters using complementary split-ring resonators

A novel method for designing miniaturised multi-band filters using the complementary split-ring resonators (CSRRs) is proposed and demonstrated on the basis of substrate integrated waveguide (SIW) technology. By loading different types of CSRRs on the waveguide surface, multiple passbands propagating below the waveguide cutoff frequency can be generated separately. The proposed structures allow relatively independent control over the centre frequency and the coupling coefficient. The working principle is illustrated by the equivalent circuit and the filter coupling methodology is introduced for design purpose. Two types of dual-passband filters, a triple-band and a quadruple-band filter are designed and fabricated to validate the proposed concept. These filters are showing advantages in terms of compact size, good selectivity and stopband rejection, as well as the easy integration capability with other circuits.

COMPACT DUAL-PASSBAND FILTER USING SPIRAL RESONATORS

A novel compact dual-band bandpass filter using spiral resonators and input/output (source-load) direct coupling structure has been presented. Two different transmission paths are utilized to realize independently controllable central frequencies and bandwidths for each passband. In addition, three transmission zeros has been introduced to improve the frequency selectivity. A dual-passband filter centered at 2.41 GHz and 4.22 GHz is designed, simulated, and fabricated to demonstrate the performance of the proposed filter structure. The measured results show good agreement with the simulated ones.

Dual mode wideband band-pass filter with notched band for communication system

This paper presents a planar microstrip wideband dual mode Band-Pass Filter (BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz. The dual mode band-pass filter consists of a ring resonator with two quarter-wavelength open-circuited stubs at Φ =90° and Φ =0°, respectively. A square perturbation stub has been put at the corner of the ring resonator to increase the narrow stopbands and improve the performance of selectivity. By using a parallel-coupled feed line, a narrow notched band is introduced at the required frequency and its Fractional BandWidth (FBW) is about 5%. The proposed filter has a narrow notched band and a wide pass-band with a sharp cutoff frequency characteristic, the attenuation rate for the sharp cutoff frequency responses is 297.17 dB/GHz (calculated from 1.959 GHz with −34.43 dB to 2.065 GHz with −2.93 dB) and 228.10 dB/GHz (calculated from 3.395 GHz with −2.873 dB to 3.507 GHz with −28.42 dB). This filter has the advantages of good insertion loss in both operating bands and two rejections of greater than 16 dB in the range of 1.59 GHz to 1.99 GHz and 3.49 GHz to 3.98 GHz. Having been presented in this article, the measurement results agree well with the simulation results, which validates our idea.

A dual band-pass amplifier-filter circuit for simultaneous recording of spikes and local field potentials from live neuronal tissue using multielectrode arrays

The paper presents the design and test results of a novel circuit with dual band-pass filter for simultaneous recording of Local Filed Potentials and spikes from individual neurons. Single readout channel is built of an input AC-coupling circuit with the cut-off frequency below 0.1Hz, a low noise preamplifier and two parallel band-pass filters with nominal bandwidths from 2Hz to 100Hz and from 200Hz to 2kHz. The design is optimized for low noise, high dynamic range, and low power dissipation. The circuit has been designed and manufactured in a 0.35μm CMOS process as a multichannel chip comprising also an analog multiplexer for serialization of the analog output signals.

Signal-Interference Stepped-Impedance-Line Microstrip Filters and Application to Duplexers

In this letter, signal-interference filtering sections shaped by two in-parallel stepped-impedance transmission lines are applied to frequency-asymmetrical microstrip filter design. When realizing single-passband filters, a different selectivity for the lower and upper stopband can be generated, making them appropriate for duplexing devices. In the case of double-passband filters, fully-asymmetrical dual bands in terms of bandwidth, cutoff slopes and class of filtering transfer function can be shaped. Examples of design curves to adjust the performances of the synthesized signal-interference section filtering profile are given, e.g., bandwidth or in-band ripple level for Chebyshev-type functions. To show practical viability, a duplexer and a spectrally-asymmetrical dual-passband filter circuit are also built and characterized.

Design of Multimode Net-Type Resonators and Their Applications to Filters and Multiplexers

Net-type resonators with dual- and tri-mode electrical behaviors have been presented and analyzed theoretically in this paper. The proposed net-type resonator is constructed by a short-ended and several open-ended transmission-line sections, which has the advantages of small size and more flexible resonant frequency allocation and is therefore particularly suitable for applications to the design of microwave devices. To verify the usefulness of the proposed resonators, three experimental examples, including a dual-mode bandpass filter, a dual-passband filter, and a triplexer, have been designed and fabricated with microstrip technology. Each of the designed circuits occupies a very small size and has a good upper stop and performance. All measured results are in good agreement with the full-wave simulation results.

Design of Microstrip Dual-Passband Filter Based on Branch-Line Resonators

A new type of microstrip dual-passband filter using branch-line resonators near the input and output ports is presented in this paper. The branch-line resonator plays two important roles for the proposed dual-band filter structure. One is for extracting the external quality factor of each band separately and the other is for providing the required resonance at the center frequency of each passband. By adding some additional resonators near the branch-line resonators, the coupling coefficients between adjacent resonators can also be obtained separately such that each passband response of the proposed dual-band filter structure can be designed individually.

곡면에 부착 가능한 GPS/GLONASS 마이크로스트립 능동 안테나

In this paper, dual-feed circularly polarized microstrip patch antenna for GPS L1, GPS L2, GLONASS L1 signal was fabricated by using stacked patch. It was fed by dual coaxial probe on the patch at 50ohm impedance, and was simulated to resonate at GPS L1, GPS L2, GLONASS L1. To realize characteristics of right hand circular polarization using dual-feed stacked patch antenna and hybrid coupler for phase difference. Output of hybrid coupler was contacted input of Low Noise Amplifier(LNA). The LNA using dual band pass filter was designed and fabricated. The measured results of the implemented antenna is VSWR

Dual-mode dual-passband microstrip bandpass filter with a high selective performance

A dual-mode bandpass filter with a high selective performance for dual-band application is presented in this article.The filter is designed with square loop resonator with tree-shaped patches attached to the four inner corners of the loop, which equivalents to load capacitors in the inner of loop resonator. This loading can reduce the size of filter. The input/output feed lines located along a straight line. Such a feed arrangement is physically suitable for certain microwave networks. A demonstrated filter with the dual-band operating at 1.6 and 2.08 GHz was designed. Simulated and measured results indicate that a high selective dual-mode dual-band filter with wide harmonic responses has been achieved. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:666–669, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25784

Dual Passband Filter Using Hybrid Microstrip Split Ring Resonators and Coplanar Waveguide Quarter Wavelength Resonators

A novel dual passband filter using hybrid microstrip split ring resonators and coplanar wavelength (CPW) quarter wavelength resonators is presented. An equivalent RLC circuit model is presented, and its corresponding parameters are also extracted from the theoretical analysis. The proposed dual passband filter has two passbands with the center frequencies of 2.44 GHz and 3.5 GHz. Good agreement among equivalent circuit (EC), electromagnetic (EM) simulated and measured results is demonstrated.

A Novel Compact 2.4/5.2 GHz Dual Wideband Bandpass Filter with Deep Transmission Zero

In this study, a novel compact 2.4/5.2 GHz dual wideband bandpass filter was designed and fabricated on an Al2O3 ceramic substrate. First, a dual-band filter was designed based on two open-loop rectangular ring (OLRR) resonators, which were cascaded using a coupling connection in order to increase the bandwidths of the dual passbands. Diverging U-shaped dual feed input/output transmission lines were used for strong coupling. A shunt quarterwavelength open stub eliminated unwanted harmonic frequencies and transmitted the desired passbands. To achieve this, four open stubs were directly added onto the two OLRR resonators as bandstop resonators to reject undesired frequencies and improve the out-of-band rejection between the two resonant frequencies. The coupling sections between the two resonators were modified using a groove structure to regulate the coupling of the two modes and eliminate the ripple at the designed 5.2 GHz band. According to simulated and measured results, the proposed filter with optimized parameters exhibited dualwide passbands with bandwidths of 530 MHz (22.84%) and 650 MHz (12.29%) at 2.32 GHz and 5.29 GHz, respectively.