Showing papers on "Prototype filter published in 2003"

Fundamentals of adaptive filtering

Abstract: Preface. Acknowledgments. Notation. Symbols. Optimal Estimation. Linear Estimation. Constrained Linear Estimation. Steepest-Descent Algorithms. Stochastic-Gradient Algorithms. Steady-State Performance of Adaptive Filters. Tracking Performance of Adaptive Filters. Finite Precision Effects. Transient Performance of Adaptive Filters. Block Adaptive Filters. The Least-Squares Criterion. Recursive Least-Squares. RLS Array Algorithms. Fast Fixed-Order Filters. Lattice Filters. Laguerre Adaptive Filters. Robust Adaptive Filters. Bibliography. Author Index. Subject Index. AC

Compact, low insertion-loss, sharp-rejection, and wide-band microstrip bandpass filters

Abstract: This paper presents a new compact, low insertion-loss, sharp-rejection, and wide-band microstrip bandpass filter. A bandstop filter is introduced that uses a ring resonator with direct-connected orthogonal feed lines. A new bandpass filter based on the bandstop filter uses two tuning stubs to construct a wide-band passband with two sharp stopbands. Without coupling gaps between feed lines and rings, there are no mismatch and radiation losses between them and, therefore, the new filters show low insertion loss. In addition, a dual-mode characteristic is used to increase the stopband bandwidth of the new filters. A simple transmission-line model used to calculate the frequency responses of the filters shows good agreement with measurements. The filter using three cascaded rings has 3-dB fractional bandwidth of 49.3%, an insertion loss of better than 1.6 dB in the passband, a return loss of larger than 13 dB from 4.58 to 7.3 GHz, and two rejections of greater than 40 dB within 2.75-4.02 and 7.73-9.08 GHz. The high-performance, compact-size, and low-cost filter was designed for reducing the interference in full duplex systems in satellite communications.

Compact elliptic-function low-pass filters using microstrip stepped-impedance hairpin resonators

Abstract: A compact elliptic-function low-pass filter using microstrip stepped-impendance hairpin resonators and their equivalent-circuit models are developed. The prototype filters are synthesized from the equivalent-circuit model using available element-value tables. To optimize the performance of the filters, electromagnetic simulation is used to tune the dimensions of the prototype filters. The filter using multiple cascaded hairpin resonators provides a very sharp cutoff frequency response with low insertion loss. Furthermore, to increase the rejection-band bandwidth, additional attenuation poles are added in the filter. The filters are evaluated by experiment and simulation with good agreement. This simple equivalent-circuit model provides a useful method to design and understand this type of filters and other relative circuits.

Improving passive filter compensation performance with active techniques

Abstract: This paper presents the performance analysis of a hybrid filter composed of passive and active filters connected in series. The analysis is done by evaluating the influence of passive filter parameters variations and the effects that different active power filter's gain have in the compensation performance of the hybrid scheme. The compensation performance is quantified by evaluating the attenuation factor in a power distribution system energizing high-power nonlinear loads compensated with passive filters and then improved with the connection of a series active power filter. Finally, compensation characteristics of the hybrid topology are tested on a 10-kVA experimental setup.

Parallel-coupled microstrip filters with over-coupled end stages for suppression of spurious responses

Abstract: In a parallel-coupled microstrip filter, end stages with over-coupling are designed to suppress the unwanted responses at twice the passband frequency (2f/sub 0/). The inherent transmission zero of an over-coupled input/output stage is shown tunable. It is found that increasing the image impedance of the filter sections can further enhance the suppression. The designed bandpass filters thus have a wide upper stopband and improved passband response symmetry. Measured results of fabricated circuits show that the idea works very well.

Bulk acoustic wave resonator with two piezoelectric layers as balun in filters and duplexers

Abstract: A bulk acoustic wave device (20) having two resonators (92, 94) in a stacked-up configuration separated by a dielectric layer (50). The device (20) can be coupled to a lattice filter or a ladder filter to form a passband filter with an unbalanced input port (41) and two balanced output ports (16, 18). One or more such passband filters can be used, together with another lattice or ladder filter, to form a duplexer having an unbalanced antenna port, two balanced ports for one transceiver part and two balanced ports for another transceiver part.

Tunable microstrip bandpass filters with two transmission zeros

Abstract: This paper presents an analytical technique for positioning the locations of two transmission zeros for a microstrip bandpass filter. In addition, this paper discusses how the tapping positions of asymmetric feed lines affect the coupling between resonators. The bandpass filter uses two resonators with two transmission zeros to obtain lower insertion loss than a conventional cross-coupled microstrip filter. Also, by using four resonators, the bandpass filter has better out-of-band rejection than the conventional cross-coupled microstrip filter. The filter designs using four cascaded resonators provide a sharp passband that can be tuned using a piezoelectric transducer to change the effective dielectric constant. The filters demonstrate high selectivity, compact size, and can be used in many wireless communication systems.

On the design of novel compact broad-band planar filters

Abstract: On the basis of impedance steps and coupled-line sections as inverter circuits, novel wide-band and very compact filters are presented. The application of alternately high- and low-impedance lines presented to the connected transmission-line resonators partly reduces their lengths to a quarter-wavelength only. In addition, effective techniques are demonstrated to reduce spurious stopband resonance resulting from a remaining half-wavelength resonator. Both suspended stripline (SSL) and microstrip filters were designed, fabricated, and tested, proving this concept in an excellent way. For the prototype filters, center frequencies around 6 GHz were selected. Bandwidths are between 2.5-3.25 GHz, and insertion-loss amounts to around 0.25 dB for the microstrip filters and 0.5 dB (including the transitions to coaxial line) for the SSL filters, respectively. For the selected center frequency and on a substrate with a dielectric constant of 10.8, the smallest microstrip filter is only 15 mm/spl times/5 mm in size.

Overlapped complex-modulated transmultiplexer filters with simplified design and superior stopbands

Abstract: A simple method for the design of the finite-impulse-response prototype filter for maximally decimated overlapped complex-modulated transmultiplexers with near perfect reconstruction property is presented. The procedure is unified for all values of overlap factor and leads to a prototype filter with excellent frequency selectivity and fast sidelobe fall-off rate. The high stopband attenuation and fast sidelobe fall-off rate, which is justified analytically, make the proposed filters suitable candidates for high-speed data communication applications employing multicarrier modulation.

A practical micropower programmable bandpass filter for use in bionic ears

Abstract: Subthreshold Gm-C filters offer the low power and wide tunable range required for use in fully implantable bionic ears. The major design challenge that must be met is increasing the linear range. A capacitive-attenuation technique is presented and refined to allow the construction of wide-linear-range bandpass filters with greater than 1 V/sub pp/ swings. For a 100-200 Hz fully differential filter with second-order roll off slopes and greater than 60 dB dynamic range, experimental results from a 1.5-/spl mu/m, 2.8-V BiCMOS chip yield only 0.23 /spl mu/W power consumption; for a 5-10 kHz filter with the same specifications the power only increased to 6.36 /spl mu/W. Fully differential filters with first-order slopes had a dynamic range of 66 dB and power consumptions of 0.12 and 3.36 /spl mu/W in the 100-200 Hz and 5-10 kHz cases, respectively. We show that our experimental results of noise and linear range are in good accord with theoretical estimates of these quantities.

Bandpass resonant filters in photonic-crystal waveguides

Abstract: A precise and effective technique for the design of bandpass resonant filters realized in a one-missing-row photonic-crystal waveguide by inserting proper defects along the waveguide is proposed. The main characteristics of photonic-crystal-based resonant filters are discussed and an application as channel-dropping filter is presented.

Reconfigurable bandpass filter with a three-to-one switchable passband width

Abstract: A reconfigurable bandpass filter is described that aims to preserve the optimal performance of a broad-band system under changing signal conditions. It does so by allowing the passband width of the system's receiver to adapt. The filter can be switched between two discrete states with widely differing bandwidths of 500 and 1500 MHz, respectively, while keeping the passband responses centered at 10 GHz. The physical implementation comprises a hybrid-integrated microstrip circuit on a 0.010-in-thick quartz substrate. The circuit employs commercial beam-lead p-i-n diodes to switch fixed-valued reactance elements. Despite the presence of semiconductor switching devices, the filter behaves very linearly, exhibiting measured passband third-order output-referenced intercept points that exceed 46 dBm in both switched states.

Controlling the spectral response in guided-mode resonance filter design

Abstract: Techniques for controlling spectral width are used in conjunction with thin-film techniques in the design of guided-mode resonance (GMR) filters to provide simultaneous control over line-shape symmetry, sideband levels, and spectral width. Several factors that could limit the minimum spectral width are discussed. We used interference effects for passband shaping by stacking multiple GMR filters on top of one another. A design is presented for a 200-GHz telecommunications filter along with a tolerance analysis. Compared with a conventional thin-film filter, the GMR filter has fewer layers and looser thickness tolerances. Grating fabrication tolerances are also discussed.

Generalization of active filters for EMI reduction and harmonics compensation

Abstract: This paper analyses general active filters that can be applicable to EMI filter, active power filter, etc. It gives generalized equations presenting insertion losses and input impedances of various kinds of active filters, from which the requirements and limitations of active filters can be identified. Based on this analysis, the effectiveness of the active filters presented in several literatures is investigated. With the results of this study, an appropriate topology of an active filter for a specific application can be selected with a good rationale.

Method and apparatus for propagating content filters for a publish-subscribe network

Abstract: A method and apparatus provide for propagating filters in a publish-subscribe network. A plurality of filters relating to subscriptions to content in the network are received. A number of the filters is reduced based upon particular criteria, and the reduced number of filters are propagated for use in satisfying the subscriptions. A filter receiving module, a filter reduction module, and a filter propagation module may execute these steps.

Three-dimensional cone filter banks

Abstract: Three dimensional (3-D) narrow cone-shaped filter passbands are ideally required for the selective filtering of sampled broad-band 3-D plane waves on the basis of their directions of arrival. A method is proposed for approximating narrow 3-D cone-shaped passbands using a 3-D cone-filter-bank structure in which the subbands consist of band limited 3-D narrow-band infinite impulse response (IIR) beam filters having 3-D uniform bandwidths that are approximately proportional to their distance from the origin in the 3-D frequency space. The 3-D beam filters may be realized from a cascade of 3-D IIR frequency-planar filters. It is shown that the proposed 3-D cone filter bank achieves low distortion of broad-band passband 3-D plane waves, and significant attenuation of broad stopband plane waves.

Inline TM/sub 110/-mode filters with high-design flexibility by utilizing bypass couplings of nonresonating TE/sub 10/01/ modes

Abstract: This paper presents a new class of pseudoelliptic function filters that are based on compact inline TM/sub 110/-mode cavity configurations. No structural folding is required. The bypass couplings are implemented through the nonresonating TE/sub 10/01/ modes so that arbitrarily positioned transmission zeros can be implemented. Design guidelines to generate a given transmission zero on the desired side of the passband and how to control it are presented. To demonstrate its flexibility, the approach is illustrated at examples of four-pole inline filters providing Chebyshev, elliptic-function-type, and asymmetric characteristics. Performance comparisons with different numerical codes validate the designs. A fourth-order pseudoelliptic filter with four transmission zeros is then designed, constructed, and measured. Excellent agreement between simulated and experimental results verifies the approach.

Narrow-band, fixed-tuned, and tunable bandpass filters with zig-zag hairpin-comb resonators

Abstract: "Hairpin-comb" filters have been previously shown to have special properties that are advantageous for the design of compact, narrow-band, and bandpass microstrip filters. Herein, a new "zig-zag" form of hairpin-comb filter is introduced, which is shown to have additional important advantages for designing compact narrow-band filters. Examples with computed responses and the measured results from high-temperature superconductor trial designs are presented. The considerable flexibility available in the design of bandpass filters of this sort is shown to be helpful in the design of tunable bandpass filters having nearly constant bandwidth and passband shape as they are tuned. Measured results for tuning over nearly an octave range are presented.

Millimeter-wave substrate integrated waveguide filters

Abstract: This paper presents the design and performance of millimeter waves filter realized with the SIW technology Using the SIW, low-cost filter can be manufactured at millimeter-wave without tuning A design methodology for Butterworth or Chebychev prototype is presented Also a dual-mode filter is presented to improve the out of band rejection An experimental inductive post Chebychev filter has been designed and measured The 3 poles, 1 GHz bandwidth filter presents 11 dB insertion losses at 28 GHz and return loss better than 163 dB Also, a dual mode filter has been designed and measured The bandwidth of the 2-poles, 1-zero filter is 07 GHz The insertion loss is 18 dB and return loss is better than 20 dB

Mechanically switchable photonic crystal filter with either all-pass transmission or flat-top reflection characteristics.

Abstract: We theoretically introduce a new type of optical all-pass filter based on guided resonance in coupled photonic crystal slabs. The filter exhibits near-complete transmission for both on- and off-resonant frequencies and yet generates large resonant group delay. We further show that such a filter can be mechanically switched into a flat-top band rejection filter.

A reduced-size dual-mode bandpass filter with capacitively loaded open-loop arms

Abstract: A novel type of dual-mode microstrip bandpass filter using degenerate modes of a dual-mode microstrip square loop resonator with capacitively loaded open-loop arms is proposed. Such a dual-mode bandpass filter with a 0.75% bandwidth at the center frequency of 1.603 GHz is designed and fabricated to demonstrate the design of reduced-size microstrip filters. It is shown that the proposed filter has a size reduction of about 59% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop and ring resonator filter.

Acoustic echo cancellation using nonlinear cascade filters

Abstract: The miniaturization of GSM handsets creates nonlinear acoustical echoes between microphones and loudspeakers when the signal level is high (hands-free communication). Several methods including nonlinear cascade filters and a bilinear filter are proposed to compensate these echoes. A bilinear filter is a restricted NARMAX (nonlinear autoregressive moving average with exogenous inputs) filter. We present an evaluation based on the standard ERLE (echo return loss enhancement) measure, between a simple linear adaptive FIR filter and various nonlinear filters. These experiments are carried out first on a simulated communication system, then on experimental signals.

Design of coupled resonator filters using admittance and scattering matrices

Abstract: The longitudinal coupling of thin film bulk acoustic resonator (FBAR) is investigated in order to design coupled resonator filter (CRF). Such devices are dedicated to high-frequency filter applications. A scattering matrix algorithm that was already used to simulate simple FBARs devices is used to study the behavior of these structures. The principle of the algorithm is recalled and is explained how it can be adapted to the simulation of multiport devices. Then an example of filter design is given.

Transmission-line filters with capacitively loaded coupled lines

Abstract: Coupled lines with loads at one end, which can create tunable transmission zeros, are studied in this paper. The equation for the transmission zeros is derived from the analysis of even- and odd-mode excitations. Based on this equation, coupled lines with different loads are analyzed and the rules for controlling the transmission-zero frequency are given. The structures are used in the designs of several second-order filters and they are experimentally verified. The use of a skew-symmetric (0/spl deg/) feed structure in these filters is also discussed and an example is given.

Optimal design of FIR frequency-response-masking filters using second-order cone programming

Abstract: Since Lim's 1986 paper on the frequency-response masking (FRM) technique for the design of FIR digital filters with very small transition widths, the analysis and design of FRM filters have been a subject of study. In this paper, a new optimization technique for the design of FRM filters is proposed. Central to the new design method is a sequence of linear updates for the design variables, with each update carried out by second-order cone programming. Design simulations are presented to illustrate the proposed algorithms and to evaluate the design performance.

Two-channel digital and hybrid analog/digital multirate filter banks with very low-complexity analysis or synthesis filters

Abstract: Multirate filter banks make use of analysis and synthesis filter banks. This paper introduces two-channel digital and hybrid analog/digital multirate filter banks where either the analysis or synthesis filters have a very low complexity. Such filter banks find application, for example, in high-speed analog-to digital converters where it is essential to minimize the complexity of the discrete-time or analog filters. The proposed digital filter banks are approximately perfect reconstruction (PR) filter banks, whereas the hybrid analog/digital filter banks can be chosen to be either approximately PR or approximately perfect magnitude reconstruction filter banks. The design is performed by first optimizing the digital or analog analysis filters and then, with the analysis filters fixed, optimizing the digital synthesis filters. This design procedure makes it possible to obtain analysis filters of very low order and complexity. The overall complexity is also low. Further, the proposed filter banks are, in all cases, very easy to design by making use of well-known and reliable optimization techniques; in particular, as small distortion and aliasing as desired are readily obtained because they are controlled in a linear programming problem. Several design examples are included, illustrating the properties of the proposed filter banks.

Pulse shaping filter design in UWB system

Abstract: This article develops an optimal pulse shaping filter design framework, which minimizes UWB signal interference to existing (or legacy) narrow band signals, such as global positioning system (GPS), satellite communication systems, etc. A 2-stage optimal filter design procedure is proposed. In the first stage, a transmission filter is optimized to satisfy an imposed transmission mask, which minimizes UWB interference to a tolerable level. In the sub-sequent optimization stage, a recovery filter is optimized to best recover the transmitted signal. The effectiveness of this procedure is demonstrated with an example, in which FCC indoor transmission spectral mask is used to design the transmission filter. This procedure makes it possible to best recover the transmitted signal while minimizing the UWB interference to other legacy systems.

Partial band reconstruction of frequency channelized filters

Abstract: A channelized filter design for partial band reconstruction having high dynamic range requirements. The analysis filter (505) and synthesis filter constraints of the present invention permit high performance signal detection with an alias free signal recombination capability for signals that span multiple frequency bins. The filter bank allows the use of a single wideband asset to provide for data channelized for detection processing with the ability to recombine one or more adjacent frequency bins into a wider bandwidth baseband time domain data stream suitable for exploitation processing. The present implementation allows the use of an efficient partial band reconstruction mechanism that allows signal reconstruction using only the frequency subchannels that pertain to the signal of interest that is to be copied. The filter design mechanism separates the specification of the analysis filter to support signal detection in environments of high dynamic range. The signal reconstruction (synthesis) filter uses fewer bins and allows a higher order filter.

A novel digitally tunable microwave-photonic notch filter using differential group-delay module

Abstract: We demonstrate a digitally tunable microwave-photonic notch filter based on a differential group-delay module which produces a relative delay between two orthogonal polarizations. A maximum rejection level greater than 60 dB is obtained. The tunability of the filter is achieved through real-time electronic control of the relative delay time.