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Showing papers on "Prototype filter published in 1998"


Journal ArticleDOI
TL;DR: In this article, the authors have characterized common nonlinear loads have been characterized into two types of harmonic sources, current-source type of harmonic source and voltage source type of source, and discussed the compensation characteristics of both parallel active filters and series active filters.
Abstract: In this article, common nonlinear loads have been characterized into two types of harmonic sources, current-source type of harmonic source and voltage-source type of harmonic source. Compensation characteristics of both parallel active filters and series active filters have been discussed analytically and experimentally for these two types of harmonic sources. The corresponding required operation conditions, features, application issues, and adaptive harmonic sources of both filters have been presented. The fact that the traditional active filter, the parallel active filter, is not a panacea to harmonic compensation, and that one cannot use it blindly, has been clearly addressed. The parallel active filter will increase harmonic current and may cause overcurrent of the load when the load is a harmonic voltage source. Instead, it has been verified that the series active filter is better suited for compensation of a harmonic voltage source such as a diode rectifier with smoothing DC capacitor. The conclusions of this article also imply that when a parallel active filter is installed in a power system network such as at a point of common coupling, the network impedance and main harmonic sources downstream from the installation point should be investigated in order to get good performance and to minimize influence to the loads downstream. In some cases, a combined system of parallel active filter and series active filter may be necessary by utilizing the harmonic isolation function of the series active filters. No doubt active filters are superior to passive filters if used in their niche applications.

524 citations


Book
16 Dec 1998
TL;DR: In this paper, the authors present an approach for the estimation of 1st and 2nd-order functions of LC ladder filters using Opamps, which is based on the Bessel-Thomson Delay Approximation Delay Equalization Frequency Transformations.
Abstract: Fundamentals Introduction Filter Characterization Types of Filters Steps in Filter Design Analysis Continuous-Time Filter Functions Stability Passivity for One- and Two-Port Networks Reciprocity The Approximation Problem Introduction Filter Specifications and Permitted Functions Formulation of the Approximation Problem Approximation to the Ideal Lowpass Filter Filters with Linear Phase: Delays Bessel-Thomson Delay Approximation Delay Equalization Frequency Transformations Design Tables of Passive LC Ladder Filters Impedance Scaling Predistortion Active Elements Introduction Ideal Controlled Sources Impedance Transformation (Generalized Impedance Converters and Inverters) Negative Resistance Ideal Operational Amplifier The Ideal Operational Transconductance Amplifier (OTA) Realization of 1st- and 2nd-Order Functions Using Opamps Introduction Realization of 1st-Order Functions The General 2nd-Order Filter Function Sensitivity of 2nd-Order Filters Realization of Biquadratic Functions Using SABs Realization of a Quadratic with a Positive Real Zero Biquads Obtained Using the Twin-Tee RC Network Two Opamp Biquads Three Opamp Biquads Realization of High-Order Functions Using Opamps Introduction Selection Criteria for High-Order Function Realizations Mutliparameter Sensitivity High-Order Function Realization Methods Cascade Connection of 2nd-Order Sections Mutli-Loop Feedback Filters Cascade of Biquartics Simulation of LC Ladder Filters Using Opamps Introduction Resistively Terminated Lossless LC ladder Filters Methods of LC Ladder Filter Simulation The Gyrator Generalized Impedance Converter FDNRs Complex Impedance Scaling Functional Simulation Wave Active Filters Introduction Wave Active Filters Wave Active Equivalents (WAE) Economical Wave Active Filters Sensitivity of WAFs Operation of WAFs at Higher Frequencies Complementary Transfer Functions Wave Simulation of Inductance Linear Transformation Active Filters (LTA Filters)

377 citations


Journal ArticleDOI
TL;DR: In this paper, a new class of cross-coupled planar microwave filters using microstrip hairpin resonators is introduced, and the theoretical and experimental performance of these filters are investigated in the light of full-wave electromagnetic simulations.
Abstract: A new class of cross-coupled planar microwave filters using microstrip hairpin resonators is introduced. The realization of bath the canonical and the cascaded quadruplet (CQ) filters is feasible. Coupling characteristics of four basic coupling structures encountered in this class of filters are investigated in the light of full-wave electromagnetic (EM) simulations. A four-pole cross-coupled filter of this type is designed and fabricated. Both the theoretical and experimental performance is presented.

229 citations


Journal ArticleDOI
TL;DR: In this article, high-performance planar micromachined filters at 37 and 60 GHz are presented, which consist of a 3.5% bandwidth two-pole Chebyshev filter with transmission zeros at 37 GHz, 2.7% and 4.3% bandwidth four-and five-pole chebbershev filters at 60 GHz, and an 8% bandwidth elliptic filter at 60GHz.
Abstract: High-performance planar micromachined filters at 37 and 60 GHz are presented. The filters consist of a 3.5% bandwidth two-pole Chebyshev filter with transmission zeros at 37 GHz, 2.7% and 4.3% bandwidth four- and five-pole Chebyshev filters at 60 GHz, and an 8% bandwidth elliptic filter at 60 GHz. Silicon micromachining techniques combined with micropackaging have been applied to allow for very high-Q resonators resulting in low-loss filters. The 37-GHz two-pole filter exhibits a 2.3-dB port-to-port insertion loss. The 2.7% and 4.3% four- and five-pole Chebyshev filters at 60 GHz exhibit 2.8- and 3.4-dB insertion loss, and the 8% elliptic filter exhibits a 1.5-dB insertion loss. These values show a large reduction of insertion loss compared to conventional planar techniques, and can be used for planar low-cost millimeter-wave wireless communication systems.

182 citations


Journal ArticleDOI
TL;DR: This work proposes limiting the search of the prototype filters to the class of filters obtained using Kaiser windows, and the design process is reduced to the optimization of a single parameter.
Abstract: The traditional designs for the prototype filters of cosine modulated filterbanks usually involve nonlinear optimizations. We propose limiting the search of the prototype filters to the class of filters obtained using Kaiser windows. The design process is reduced to the optimization of a single parameter. An example is given to show that very good designs can be obtained in spite of the limit of search.

181 citations


Journal ArticleDOI
TL;DR: In this paper, the group delay of the input reflection coefficients of sequentially tuned resonators has been shown to provide all the information necessary to design and tune filters, and that the group-delay value at the center frequency of the filter can be written quite simply in terms of the low pass prototype values, the LC elements of a bandpass structure, and the coupling coefficients of the inverter coupled filter.
Abstract: The concept of coupling coefficients has been a very useful one in the design of small-to-moderate bandwidth microwave filters. It is shown in this paper that the group delay of the input reflection coefficients of sequentially tuned resonators contains all the information necessary to design and tune filters, and that the group-delay value at the center frequency of the filter can be written quite simply in terms of the low-pass prototype values, the LC elements of a bandpass structure, and the coupling coefficients of the inverter coupled filter. This provides an easy method to measure the key elements of a filter, which is confirmed by results presented in this paper. It is also suggested that since the group delay of the reflection coefficient (i.e., the time taken for energy to get in and out of the coupled resonators) is easily measured, it is a useful conceptual alternative to coupling concepts.

162 citations


Journal ArticleDOI
Christi K. Madsen1
TL;DR: A new architecture using optical all-pass filters is presented which can realize Butterworth, Chebyshev, and elliptic bandpass filter designs exactly and efficiently using either ring resonators or reflectors such as Bragg gratings or thin-film interference filters.
Abstract: Butterworth, Chebyshev, and elliptic bandpass filter designs are optimal in the sense of band flatness or equiripple characteristics. A new architecture using optical all-pass filters is presented which can realize these designs exactly and efficiently using either ring resonators or reflectors such as Bragg gratings or thin-film interference filters. Design examples are given for a seventh- and eighth-order elliptic filter, and the new architecture is shown to be tolerant to loss. Previously, reflective filters could only approximate optimal responses. An order of magnitude improvement in transition width is demonstrated for an elliptic filter compared to an optimized transmission response for an individual thin-film filter.

140 citations


Journal ArticleDOI
TL;DR: In this paper, the feasibility of a three phase active filter based on a half-bridge topology was demonstrated and design guidelines for the power circuit have been derived and applied to a 5 kVA IGBT laboratory prototype.
Abstract: This article has demonstrated the feasibility of a three phase active filter based on a half-bridge topology. Design guidelines for the power circuit have been derived and applied to a 5 kVA IGBT laboratory prototype. In the single phase mode, the active filter can reduce the low frequency harmonic content in the AC line to below 1% excluding the harmonics due to switching action of the converter. In the three phase mode, line currents are corrected under balanced and unbalanced conditions. The neutral current is reduced significantly.

112 citations


Journal ArticleDOI
TL;DR: In this article, two identical microstrip open-loop resonators with coupled and crossing lines have been designed and fabricated for elliptic-function narrow-band bandpass filters with a measured 3dB bandwidth of 2% and two deep notches in its stopband.
Abstract: Novel compact elliptic-function narrow-band bandpass filters have been designed and fabricated. This new configuration consists of two identical microstrip open-loop resonators with coupled and crossing lines. A theoretical investigation has confirmed that this novel configuration is capable of providing elliptic-function filtering. Furthermore, the feasibility of this filter is verified experimentally. Centered at 2.039 GHz, the fabricated microstrip bandpass filter shows a measured 3-dB bandwidth of 2% and two deep notches in its stopband. In addition, the main circuit of this filter occupies only 2.5 cm/spl times/1.5 cm using a substrate with dielectric constant of 10.5, making it very attractive for applications in the mobile and personal communication systems (PCS's).

101 citations


Journal ArticleDOI
TL;DR: In this article, the harmonic amplification problems in a plastics plant and the appropriate mitigation methods were investigated and two high-pass damped filters were recommended to replace the original single-tuned filters.
Abstract: This paper investigates the harmonic amplification problems in a plastics plant and the appropriate mitigation methods. Four single-tuned filters (LC filters) were installed to eliminate the harmonic currents from three 6-pulse rectifiers. However, after the capacitance reduction of some filter capacitors, the driving point impedance at the frequency of 8th order harmonic increased severely and the harmonic current of this order was amplified. There were many failures of the power filter capacitors. Field measurements and computer simulations are used to verify the disturbance problems. Finally, two high-pass damped filters are recommended to replace the original single-tuned filters. The amplification problems at some even-order harmonics can be avoided.

94 citations


Journal ArticleDOI
TL;DR: The development of a filter bank structure which combines the flexibility of the short-time Fourier transform (STFT) with the implementation efficiency of the polyphase filter bank decomposition, meeting these requirements and leading to a hardware-efficient implementation, is presented.
Abstract: An approach is presented to realizing a digital channelized receiver for signal intercept applications that provides a hardware efficient implementation of a uniform filter bank in which the number of filters K is greater than the decimation factor M. The proposed architecture allows simple channel arbitration logic to be used and provides reliable instantaneous frequency measurements, even in adjacent channel crossover regions. In the proposed implementation of the filter bank, K is related to M by K=FM where F is an integer. It is shown that the optimum selection of F allows the instantaneous frequency measurement to be made in the channel crossover region and the arbitration function to be based solely on the instantaneous frequency measurement. The development of a filter bank structure which combines the flexibility of the short-time Fourier transform (STFT) with the implementation efficiency of the polyphase filter bank decomposition, meeting these requirements and leading to a hardware-efficient implementation, is presented.

Journal ArticleDOI
TL;DR: In this paper, a general analysis of the phase response of optical filters used in WDM systems is presented, and some filters are found to be inherently linear phase filters and in principle are dispersionless.
Abstract: The phase response of optical filters determines their dispersive properties and impacts wavelength-division multiplexing (WDM) system performance. We present a general analysis of the phase response of optical filters used in WDM systems and suggest ways to minimize the detrimental dispersive effects of these filters. Some filters are found to be inherently linear phase filters and in principle are dispersionless. We also show that some filters may be realized for the phase correction of dispersive filters. Experimental system results demonstrate the negative effects of filter dispersion on system performance.

Journal ArticleDOI
TL;DR: The problem of allpass filter design for phase approximation and equalization in the Chebyshev sense is solved by using a generalized Remez algorithm, which yields a solution to a variety of filter design problems.
Abstract: The problem of allpass filter design for phase approximation and equalization in the Chebyshev sense is solved by using a generalized Remez algorithm. Convergence to the unique optimum is guaranteed and is achieved rapidly in the actual implementation. The well-known numerical problems for higher degree filters are analyzed and solved by a simple approach. The algorithm yields a solution to a variety of filter design problems such as the design of filters with a desired phase response (e.g., a delay element), the design of phase equalizers, or the design of recursive filters with magnitude prescriptions using parallel allpass filters. For the latter, the algorithm can be modified to allow arbitrary tolerance schemes for the magnitude response.

Journal ArticleDOI
TL;DR: A multistage adaptive filtering system which generates the current reference delaylessly and accurately is introduced, making it possible to extract the sinusoidal active current from the distorted waveform without harmful phase shift, even when the frequency and amplitude alter simultaneously.
Abstract: Active power filters are used to eliminate AC harmonic currents by injecting equal but opposite compensating currents. Successful control of active filters requires, among other things, an accurate current reference. In this paper, we introduce a multistage adaptive filtering system which generates the current reference delaylessly and accurately. Our filter structure combines a low-pass prefilter and an adaptive predictive filter, making it possible to extract the sinusoidal active current from the distorted waveform without harmful phase shift, even when the frequency and amplitude alter simultaneously. Although active filters are typically used to compensate for the supply harmonics, where the fundamental frequency remains almost constant, we will show that our filter structure can also be applied in applications where the frequency alters rapidly.

Journal ArticleDOI
TL;DR: A new class of filters for multichannel image processing is introduced, which constitutes a generalization of vector directional filters that use fuzzy transformations of the angles among the different vectors to adapt to local data in the image.
Abstract: A new class of filters for multichannel image processing is introduced and analyzed. This class constitutes a generalization of vector directional filters. The proposed filters use fuzzy transformations of the angles among the different vectors to adapt to local data in the image. The principle behind the new filters is explained and comparisons with other popular nonlinear filters are provided. The specific case of color image processing is studied as an important example of multichannel image processing. Simulation results indicate that the new filters offer some flexbility and have excellent performance.

Book
01 May 1998
TL;DR: In this paper, the authors investigated the implementation, design, and limitations of oversampled subband adaptive filter systems based on modulated complex and real valued filter banks and proposed a highly efficient polyphase implementation of a complex valued modulated generalized DFT (GDFT) filter bank with a judicious selection of properties for non-integer oversampling ratios.
Abstract: For a number of applications like acoustic echo cancellation, adaptive filters are required to identify very long impulse responses. To reduce the computational cost in implementations, adaptive filtering in subband is known to be beneficial. Based on a review of popular fullband adaptive filtering algorithms and various subband approaches, this thesis investigates the implementation, design, and limitations of oversampled subband adaptive filter systems based on modulated complex and real valued filter banks. The main aim is to achieve a computationally efficient implementation for adaptive filter systems, for which fast methods of performing both the subband decomposition and the subband processing are researched. Therefore, a highly efficient polyphase implementation of a complex valued modulated generalized DFT (GDFT) filter bank with a judicious selection of properties for non-integer oversampling ratios is introduced. By modification, a real valued single sideband modulated filter bank is derived. Non-integer oversampling ratios are particularly important when addressing the efficiency of the subband processing. Analysis is presented to decide in which cases it is more advantageous to perform real or complex valued subband processing. Additionally, methods to adaptively adjust the filter lengths in subband adaptive filter (SAF) systems are discussed. Convergence limits for SAFs and the accuracy of the achievable equivalent fullband model based on aliasing and other distortions introduced by the employed filter banks are explicitly derived. Both an approximation of the minimum mean square error and the model accuracy can be directly linked to criteria in the design of the prototype filter for the filter bank. Together with an iterative least-squares design algorithm, it is therefore possible to construct filter banks for SAF applications with pre-defined performance limits. Simulation results are presented which demonstrate the validity and properties of the discussed SAF methods and their advantage over fullband and critically sampled SAF systems.

Journal ArticleDOI
TL;DR: It is demonstrated that this approach performs noise reduction as well as edge enhancement and improves the contrast enhancement in comparison with other methods.

Proceedings ArticleDOI
01 Oct 1998
TL;DR: To overcome technological constraints, it is shown that an optimum approach consists in the use of a multi-layer, multi-technology process, and preliminary experimental results prove the validity of this approach, and allow some extensions to more complex sub-systems.
Abstract: In this paper, we discuss about the synthesis and the implementation of a multi-function antenna/filter device, which appears as an optimum response in relation with the system's physical and electrical evolutions. Due to the extensive development of the uniplanar technology, our investigations concern the integration of a uniplanar slotline dipole directly in a standard Tchebyscheff band-pass filter. As a result, such a combination appears like a convenient solution for improving the performances of the basic antenna. To overcome technological constraints, we show that an optimum approach consists in the use of a multi-layer, multi-technology process. Preliminary experimental results prove the validity of this approach, and allow some extensions to more complex sub-systems.

Journal ArticleDOI
TL;DR: In this article, a 4-MHz, fifth-order elliptic low-pass Gm-C filter is described whose characteristics are tuned by an on-chip automatic tuning circuit.
Abstract: A 4-MHz, fifth-order elliptic low-pass Gm-C filter is described whose characteristics are tuned by an on-chip automatic tuning circuit. The tuning circuit uses only one integrator as the master of tuning instead of problematic voltage controlled oscillator (VCO) and voltage controlled filter (VCF). MOS transistors in linear operation region perform the voltage-to-current conversion in an operational transconductance amplifier, and thereby we achieved /spl plusmn/1.5 V operation. A prototype filter was implemented in a 0.8-/spl mu/m double-poly, double-metal CMOS process. The filter exhibits the dynamic range of 57.6 dB and dissipates 10 mW with /spl plusmn/1.5-V supply. The stopband attenuation is better than 45.0 dB and the passband ripple is smaller than 1.0 dB.

Journal ArticleDOI
TL;DR: A new current-mode multifunction filter with a single input and three outputs employing only three positive type CCIIs and five passive elements is presented, realising three filter functions simultaneously all at high impedance outputs.
Abstract: A new current-mode multifunction filter with a single input and three outputs employing only three positive type CCIIs and five passive elements is presented. The proposed filter realises three filter functions simultaneously all at high impedance outputs. No component matching is required and all passive sensitivities are low.

Journal ArticleDOI
TL;DR: This work introduces a new generation of perfect-reconstruction filter banks that can be obtained from classical critically sampled filter banks by means of frequency transformations and constructs new orthogonal and complete sets of wavelets whose passbands are not octave spaced and may be designed by selecting a single parameter.
Abstract: We introduce a new generation of perfect-reconstruction filter banks that can be obtained from classical critically sampled filter banks by means of frequency transformations. The novel filters are Laguerre type IIR filters that can be directly derived and designed from ordinary orthogonal or biorthogonal filter banks. Generalized downsampling and upsampling operators based on dispersive delay lines are the building blocks of our structures. By iterating the filter banks, we construct new orthogonal and complete sets of wavelets whose passbands are not octave spaced and may be designed by selecting a single parameter.

Journal ArticleDOI
D.R. Frey1
TL;DR: In this article, the general state-space synthesis of linear filters is reviewed including the use of linear transformations and time-varying nonlinear mappings on the state variables.
Abstract: The general state-space synthesis of linear filters is reviewed including the use of linear transformations. Then the use of time-varying nonlinear mappings on the state variables is shown to produce equations for the synthesis of linear, linear companding, and log-domain filters. Formulas are developed which underlie the realization of log-domain filters. Design issues relating to realizability, noise, and nonideal performance are discussed using the state-space mathematical formulation.

Journal ArticleDOI
TL;DR: In this article, the feasibility of all-dielectric waveguide grating filters is demonstrated, using a genetic algorithm (GA) to solve for material dielectric constants and geometric boundaries separating homogeneous regions of the periodic cell.
Abstract: The feasibility of novel all-dielectric waveguide grating filters is demonstrated, using a genetic algorithm (GA) to solve for material dielectric constants and geometric boundaries separating homogeneous regions of the periodic cell. In particular, the GAs show that simple geometries (not previously reported) utilizing a small number of layers and/or gratings can be found to yield bandpass or stop-band filters with user defined linewidth. The evaluation of the fitness of a candidate design entails the solution of an integral equation for the electric field in the cell using the method of moments (MoM). Our implementation is made efficient by using only very few design frequency points and accurately approximating a given filter transfer function by a quotient of polynomials as a function of frequency. Additionally, the problem impedance matrices are conveniently represented as the product of a material independent matrix and a vector of dielectric constants, thus allowing us to fill the matrices only once. Our code has been parallelized for the Cray T3D to take advantage of the intrinsic parallelization efficiencies offered by the GAs. Solutions are illustrated for a very narrow-band single-grating transmission filter and a relatively broad-band double grating reflection filter. Additionally, a solution for a five homogeneous layers Fabry-Perot filter is also presented.

Proceedings ArticleDOI
31 May 1998
TL;DR: In this paper, a 3D discrete wavelet transform (DWT) approach is proposed for performing 3D compression, and two architectures are presented.
Abstract: Compression is a significant operation in many 3D data applications, such as magnetic resonance imaging (MRI), medical diagnosis, television, and seismic data. Employing standard 2D compression techniques do not offer efficient solutions in these applications. In this paper, a 3D discrete wavelet transform (DWT) approach is proposed for performing 3D compression. Two architectures are presented. The first architecture, called 3D-I, is a straight-forward implementation of the 3D DWT. It allows even distribution of the processing load onto 3 sets of filters, with each set doing the calculations for one dimension. The filters are easily scalable to a larger size. The control for this design is very simple, since the data are operated on in a row-column-slice fashion. The design is cascadable. Due to pipelining, all filters are utilized 100% of the time, except for the start up and wind-down times. The second proposed architecture, 3D-II, uses block inputs to reduce the amount of on-chip memory. It has a control unit to select which coefficients to pass on to the low and high pass filters. The RAM on the chip is small compared to the input size, since it depends solely on the filter sizes. The filters are parallel, since systolic filters assume that the data is fed in a non-block form such that partial calculations are done.

Proceedings ArticleDOI
15 Feb 1998
TL;DR: The proposed filter characterization method makes it useful to predict EMI filter performance when the filter is used in a practical power supply.
Abstract: The proposed filter characterization method makes it useful to predict EMI filter performance when the filter is used in a practical power supply. High frequency parasitic effects can also be predicted using this method. An impedance/gain-phase analyzer is needed for this approach.

Proceedings ArticleDOI
04 Oct 1998
TL;DR: It is shown that a significant subjective improvement in the restored image quality as well as a consistent reduction in the objectively measured mean absolute error and mean square error is obtained.
Abstract: We introduce a new class of nonlinear filters called median-rational hybrid filters (MRHF) based on rational functions (RF). The filter output is the result of a rational operation taking into account three sub-functions, such as two FIR or median sub-filters and one center weighted median filter (CWMF). The proposed MRHF filters have the inherent property that on smooth areas they provide good noise attenuation whereas on changing areas the noise attenuation is traded for good response to the change. The performance of the proposed filter is compared against widely known nonlinear filters such as: morphological signal adaptive median filters, stack filters, rank-order morphological filters and simple rational filters. It is shown that a significant subjective improvement in the restored image quality as well as a consistent reduction in the objectively measured mean absolute error and mean square error is obtained.

Journal ArticleDOI
TL;DR: A fully integrated BiCMOS continuous-time filter for video signal processing applications is presented that incorporates an input clamping circuit, a third-order equalizer, a fifth-order elliptic filter with sinx/x correction, and a 75-/spl Omega/ driver to meet the linearity requirement for the broadcast-quality video system.
Abstract: A fully integrated BiCMOS continuous-time filter for video signal processing applications is presented. It incorporates an input clamping circuit, a third-order equalizer, a fifth-order elliptic filter with sinx/x correction, and a 75-/spl Omega/ driver. The architectures of the input and output amplifiers as well as the filter and the equalizer are chosen based on the extensive study of circuit structures and Monte Carlo simulation to meet the linearity requirement for the broadcast-quality video system. The complete chip achieves a low-pass filter response with a 5.5-MHz cutoff frequency (f/sub cc/), 0.3-dB passband ripple, 20-ns group delay variation up to 0.9 f/sub c/, and 43-dB attenuation at 1.45 f/sub c/. With a nominal 2-Vpp signal at the output, measured results show 0.2% differential gain, 0.38/spl deg/ differential phase, and 1.7-mV rms noise demonstrating 10-bit linearity in a 1.5-/spl mu/m 4-GHz BiCMOS process technology. The filter active area is 8 mm/sup 2/ and it dissipates 350 mW in a single 5-V power supply.

Patent
18 Nov 1998
TL;DR: In this paper, a notch filter (100) was proposed to augment the stopband rejection of a cascaded surface acoustic wave ladder filter (SAWL) with a pole at a desired passband.
Abstract: A notch filter ( 100 ) includes a parallel coupled delay line ( 104 ) and surface acoustic wave resonator ( 102 ) which provides a pole at a desired passband. The surface acoustic wave resonator ( 102 ) and the delay line ( 104 ) are configured to provide a zero at an undesired frequency or stopband. In this way, the notch filter ( 100 ) augments the stopband rejection of an associated cascaded surface acoustic wave ladder filter ( 105 ). The notch filter ( 100 ) also provides a pole at a desired frequency or passband such that losses due to the notch filter ( 100 ) at the desired passband are minimized, thereby improving overall insertion loss performance.

Journal ArticleDOI
TL;DR: In this paper, a rigorous design of dielectric resonator (DR) filters applying the finite element method (FEM) was described. But the authors only considered the dual-mode cavity multipole filters and did not consider higher order modes.
Abstract: The progress of numerical techniques now permit us to analyze rigorously complex devices such as dual-mode cavity multipole filters or planar passive elements for coplanar monolithic microwave integrated circuits (MMICs). In this paper, we describe a rigorous design of dielectric resonator (DR) filters applying the finite-element method (FEM). We first present a dual mode coupling technique which replaces classical DRs, coupling, and tuning screws, which are commonly used in dual-mode filters, by slotted DRs. Next, a new theoretical analysis based on the contribution to the dual-mode filter response of the first DR hybrid mode and of higher order modes is described. This analysis can be applied to any type of microwave dual-mode filter. It allows us to define a procedure which explains the presence and controls the position of the two transmission zeros in the filter responses. In this paper, this procedure has been applied to improve filtering performances of a dual-mode DR filter. Finally, a synthesis method is developed to rigorously design for the first time, a four- and an eight-pole slotted DR elliptic filters. The experimental results were obtained with no tuning and the theoretical ones show good agreement.

Journal ArticleDOI
TL;DR: In this article, an extension of the frequency response masking (FRM) technique to the synthesis of sharp two-dimensional (2D) diamond-shaped (DS) filters is presented.
Abstract: The frequency-response masking (FRM) technique is an efficient method for realizing sharp one-dimensional (1-D) filters. Sharp 1-D filters realized using the FRM technique have considerably lower complexity than those realized in the direct form. In this paper, we present an extension of the FRM technique to the synthesis of sharp two-dimensional (2-D) diamond-shaped (DS) filters. The new technique, based upon dividing the frequency spectrum into four complementary components and the utilization of four masking filters, achieves large reductions in filter implementation complexity when the transition width of the desired DS filter is very narrow. An expression for the impulse response up-sampling ratio that produces the design with the least complexity is derived. Extensions of the technique for the synthesis of 2-D filters other than the DS filters are also discussed.