Showing papers on "Butterworth filter published in 2014"
TL;DR: This paper addresses the problem of filtering noisy data for the particular case where the underlying signal comprises a low-frequency component and a sparse or sparse-derivative component and shows that a particular choice of discrete-time filter, namely zero-phase noncausal recursive filters for finite-length data formulated in terms of banded matrices, makes the algorithms effective and computationally efficient.
Abstract: This paper seeks to combine linear time-invariant (LTI) filtering and sparsity-based denoising in a principled way in order to effectively filter (denoise) a wider class of signals. LTI filtering is most suitable for signals restricted to a known frequency band, while sparsity-based denoising is suitable for signals admitting a sparse representation with respect to a known transform. However, some signals cannot be accurately categorized as either band-limited or sparse. This paper addresses the problem of filtering noisy data for the particular case where the underlying signal comprises a low-frequency component and a sparse or sparse-derivative component. A convex optimization approach is presented and two algorithms derived: one based on majorization-minimization (MM), and the other based on the alternating direction method of multipliers (ADMM). It is shown that a particular choice of discrete-time filter, namely zero-phase noncausal recursive filters for finite-length data formulated in terms of banded matrices, makes the algorithms effective and computationally efficient. The efficiency stems from the use of fast algorithms for solving banded systems of linear equations. The method is illustrated using data from a physiological-measurement technique (i.e., near infrared spectroscopic time series imaging) that in many cases yields data that is well-approximated as the sum of low-frequency, sparse or sparse-derivative, and noise components.
130 citations
TL;DR: In this paper, the inductor-trap-capacitor-inductor (LTCL) filter was proposed to attenuate the harmonic currents around the multiples of switching frequencies and guarantee -60 dB/decade attenuation in the high-frequency band, leading to a decrease of the total inductance and volume.
Abstract: This paper presents a new high-order filter for three-phase grid-connected voltage source converters (VSCs) named the inductor-trap-capacitor-inductor (LTCL) filter, in which multiple LC trap filters are inserted in parallel with the branch of the capacitor in the traditional LCL filter to compose multiple series resonant circuits at the selected frequencies. Particularly, the LTCL filter can attenuate the harmonic currents around the multiples of switching frequencies and guarantee -60 dB/decade attenuation in the high-frequency band, leading to a decrease of the total inductance and volume. Furthermore, within half of the switching frequency range, an LTCL -filter-based grid-connected VSC has almost the same frequency-response characteristic as that with the traditional LCL filter. That is to say, the LTCL filter does not bring any extra control difficulties. The basic parameter selection criteria and the parameter design procedure of the LTCL filter are introduced. Moreover, the sensitivity analysis of the LTCL filter is analyzed and discussed in detail. The comparative analysis and discussion considering the LCL filter, the LLCL filter, the multituned traps filter, and the proposed LTCL filter, have been presented and evaluated through the experiments on a 65-kW three-phase grid-connected VSC prototype.
88 citations
TL;DR: This is the first attempt to design such fractional Butterworth filters in complex w-plane instead of complex s-plane, as conventionally done for integer order filters, and the concept of fractional derivatives and w-planes stability of linear fractional order systems are discussed.
72 citations
07 Mar 2014
TL;DR: Experimental results indicate that, the subjects are mostly inspired on Toyota brand vehicles compared to other brands.
Abstract: This work aims to identify the most preferred brand on automotive in Malaysia through wireless EEG signals. A group of four major vehicle brand advertisements such as Toyota, Audi, Proton and Suzuki is considered on this work. An advertisement (video) of above said brands were used to simulate the subjects (9 male and 3 female with age range of 22-24 years) and the brain signal responses for the stimuli were collected using 14 channel wireless Emotiv headset with a sampling frequency of 128 Hz. The acquired signals are preprocessed using 4th order Butterworth band pass filter with a cut off frequency of 0.5 Hz-60 Hz and smoothed using Surface Laplacian filter. The alpha frequency band (8 Hz-13 Hz) of EEG signal information has been extracted using the Butterworth 4th order filter. The frequency spectrum of Alpha band is obtained through Fast Fourier Transform (FFT) to extract three statistical features such as power spectral density (PSD), spectral energy (SE) and spectral centroid (SC) from the EEG signals. Extracted features on all the subjects over four different advertisement stimuli are used to develop the feature vector. This feature vector is further given to a two non-linear classifiers namely K Nearest Neighbor (KNN) and Probabilistic Neural Network (PNN) for classifying the subject intention on advertisements. This present experimental results indicate that, the subjects are mostly inspired on Toyota brand vehicles compared to other brands. The maximum mean classification rate of 96.62% is achieved using PSD feature and PNN classifier.
72 citations
TL;DR: It is proved that when setting properly width of the basic functions, the inverse F-transform of the time series closely approximates its trend-cycle, which means that the F- transform almost completely removes the seasonal component and noise.
71 citations
TL;DR: A discrete-time IIR low-pass filter that achieves a high-order of filtering through a charge-sharing rotation and its sampling rate is then multiplied through pipelining, thus being compatible with digital nanoscale technology.
Abstract: In this paper, we propose a discrete-time IIR low-pass filter that achieves a high-order of filtering through a charge-sharing rotation. Its sampling rate is then multiplied through pipelining. The first stage of the filter can operate in either a voltage-sampling or charge-sampling mode. It uses switches, capacitors and a simple gm-cell, rather than opamps, thus being compatible with digital nanoscale technology. In the voltage-sampling mode, the gm-cell is bypassed so the filter is fully passive. A 7th-order filter prototype operating at 800 MS/s sampling rate is implemented in TSMC 65 nm CMOS. Bandwidth of this filter is programmable between 400 kHz to 30 MHz with 100 dB maximum stop-band rejection. Its IIP3 is +21 dBm and the averaged spot noise is 4.57 nV/$surd$ Hz. It consumes 2 mW at 1.2 V and occupies 0.42 mm 2.
70 citations
TL;DR: A gain-boosted N- path SC bandpass filter (GB-BPF) with a number of sought features, based on a transconductance amplifier with an N-path SC branch as its feedback network, offering double RF filtering at the input and output of the Gm in one step and reduced physical capacitance thanks to the loop gain offered by Gm.
Abstract: The demand of highly-integrated multi-band transceivers has driven the development of blocker-tolerant software-defined radios that can avoid the cost (and loss) of the baluns and SAW filters [1, 2, 3].
61 citations
TL;DR: In this paper, a triple-passband, dual-stopband filter consisting of six cascaded singlets is introduced in substrate integrated waveguide (SIW) technology, each singlet produces one independent transmission zero (TZ).
Abstract: A triple-passband, dual-stopband filter consisting of six cascaded singlets is introduced in substrate integrated waveguide (SIW) technology. Each singlet produces one independent transmission zero (TZ). Four of six TZs are placed within the filter passband, producing three passbands separated by two stopbands. The corresponding coupling matrix is synthesized based on a combination of well-known analytic and optimization methods. The SIW filter is designed for stopbands centered at 10.25 and 11.23 GHz, and passbands at 9.72, 10.76, and 11.76 GHz. The prototype is fabricated and measured. Good agreement between simulated and measured results is achieved.
52 citations
TL;DR: Several alternative ways of exploiting non-Gaussian distributional features are considered, including some that can in principle identify direct, positive feedback relations (graphically, 2-cycles) and combinations of methods that can identify high dimensional graphs.
51 citations
TL;DR: In this article, the authors investigated the impedance interaction between the EMI filter and the noise propagation path, and its influences on the filter design, and proposed a method to improve the filter's high-frequency performance using an impedance mismatching filter.
Abstract: This letter investigates into the impedance interaction between the electromagnetic interference (EMI) filter and the noise propagation path, and its influences on the filter design. It proves that the impedance resonance in the propagation path decreases the filter's high-frequency in-circuit attenuation. This letter proposes a method to improve the filter's high-frequency performance using an impedance-mismatching filter. The impedance-mismatching filter damps the resonance in the common mode (CM) noise propagation path and eliminates the high-frequency noise spike. By applying this method in the filter design, the CM inductor of the EMI filter can be significantly reduced since the EMI filter avoids the overdesign caused by its high-frequency performance degradation, and the filter can potentially achieve high power density. This letter also proposed a design procedure for this impedance-mismatching filter. An improved EMI filter design method considering this impedance mismatching is also proposed in this letter.
49 citations
TL;DR: In this paper, two equal-split Wilkinson power dividers (WPDs) were developed, and two Butterworth filter transformers were integrated in the proposed Type I divider to perform filter response and power split functions.
Abstract: This paper involved developing two (Type I and Type II) equal-split Wilkinson power dividers (WPDs). The Type I divider can use two short uniform-impedance transmission lines, one resistor, one capacitor, and two quarter-wavelength ( \(\lambda/4 \) ) transformers in its circuit. Compared with the conventional equal-split WPD, the proposed Type I divider can relax the two \(\lambda/4 \) transformers and the output ports layout restrictions of the conventional WPD. To eliminate the number of impedance transformers, the proposed Type II divider requires only one impedance transformer attaining the optimal matching design and a compact size. A compact four-way equal-split WPD based on the proposed Type I and Type II dividers was also developed, facilitating a simple layout, and reducing the circuit size. Regarding the divider, to obtain favorable selectivity and isolation performance levels, two Butterworth filter transformers were integrated in the proposed Type I divider to perform filter response and power split functions. Finally, a single Butterworth filter transformer was integrated in the proposed Type II divider to demonstrate a compact filtering WPD.
TL;DR: Measurements of a CTDSM with a built-in VGA and a second order Butterworth filter show that the in-band/out-of-band IIP 3 improves by about 3/10 dB when compared to the filter-CTDSM cascade, and achieves a similar dynamic range and consumes 25% lower power.
Abstract: Continuous-time ΔΣ modulators (CTDSM) used in wireless systems need to process signals in the presence of interferers. Peaking in the Signal Transfer Function of a conventional design necessitates a higher in-band dynamic range to accommodate interferers. A filter up front solves this problem at the expense of increased power dissipation and degraded linearity of the signal chain. Embedding the filter in the modulator achieves the same objective in a power efficient manner, while improving out-of-band linearity and reducing active area. However, having the filter inside a ΔΣ loop can be problematic with respect to stability. We show that such a system can be stabilized in a robust manner without extra hardware. Measurements of a CTDSM (signal BW = 2 MHz), with a built-in VGA (0 to 18 dB) and a second order Butterworth filter (4 MHz cutoff), show that the in-band/out-of-band IIP 3 improves by about 3/10 dB when compared to the filter-CTDSM cascade, and achieves a similar dynamic range and consumes 25% lower power.
TL;DR: In this paper, a tunable bandpass filter with a reconfigurable-pole response is presented, which can obtain 2-, 3-, and 4-pole states based on employing series resonators with RF switches.
Abstract: This paper presents a tunable bandpass filter with a reconfigurable-pole response. 2-, 3-, and 4-pole states can be obtained based on employing series resonators with RF switches. The synthesis for the proposed filter is established, and the bandwidth for each pole state can be selected based on theory. The filter is built on a Duroid substrate with er=10.2 and h=25 mil. The tuning for the center frequency is done using Schottky diodes, and the selection of the filter poles is achieved using RF microelectromechanical systems switches. A tuning of 0.73-1.03 GHz is achieved with a 1-dB fractional bandwidth of 3.9%-5.2%. The rejection levels at 200-MHz offset frequency of 2-, 3-, and 4-pole states are 28, 36, and 45 dB, respectively. This filter topology can find applications in reconfigurable radios with dynamic rejection levels.
TL;DR: A new class of feedback amplifiers, called switched-mode operational amplifiers (SMOAs) that address voltage-swing limitations of classical feedback amplifier in scaled CMOS technologies, and provide near-rail-to-rail output-signal swing, high output-stage efficiency and better linearity are introduced.
Abstract: We introduce a new class of feedback amplifiers, called switched-mode operational amplifiers (SMOAs) that address voltage-swing limitations of classical feedback amplifiers in scaled CMOS technologies. By exploiting the increased timing resolution available in scaled CMOS, SMOAs encode analog signal information in the time domain and provide near-rail-to-rail output-signal swing, high output-stage efficiency and better linearity. A 4th-order, 70 MHz continuous-time active-RC Butterworth filter is presented in 65 nm CMOS to demonstrate the advantages of SMOAs. The filter consumes 25.4 mW from a 0.6 V supply and achieves 55.8 dB peak SNDR while operating at a full-scale of 873 mV ppd. Thanks to SMOAs, the full-scale (73% of the 0.6 V supply voltage) and the bandwidth are respectively, a 2.5 × and 6.2 × improvement over other state-of-the-art low-voltage filters.
01 Dec 2014
TL;DR: The present paper deals with removing of noise from ECG of high frequency contents with help of Low pass digital filter of the cutoff frequency 100Hz with detail design of the digital Butterworth filter and its realization.
Abstract: ECG is the main tool used by the physicians for identifying and for interpretation of Heart condition. The ECG should be free from noise and of good quality for the correct diagnosis. In real time situations ECG are corrupted by many types of artifacts. The high frequency noise is one of them. The present paper deals with removing of noise from ECG of high frequency contents with help of Low pass digital filter of the cutoff frequency 100Hz. The sampling period used is .001sec. The filter is designed with Butterworth Approximations. The results of before filtration and after filtration are depicted in the paper. Paper contains detail design of the digital Butterworth filter and its realization. The experimentation is performed on the database generated in Laboratory. The simulation results show the filter works satisfactorily with some modifications in PQRST waveform.
TL;DR: 6th order Butterworth filter was chosen because it is flat in the pass band and has no amount of ripples in the stop band and this filter is designed for the signal analysis and also compared with other filters.
Abstract: A signal is the entity
that carries information. In the field of communication signal is the time varying
quantity or functions of time and they are interrelated by a set of different equations,
but some times processing of signal is corrupted due to adding some noise in the
information signal and the information signal become noisy. It is very important
to get the information from corrupted signal as we use filters. In this paper, Butterworth
filter is designed for the signal analysis and also compared with other filters.
It has maximally flat response in the pass band otherwise no ripples in the pass
band. To meet the specification, 6th order Butterworth filter was chosen
because it is flat in the pass band and has no amount of ripples in the stop band.
01 Sep 2014
TL;DR: It is shown that the filter structure can be easily extended to multi-input filter without any additional components, providing also all-pass and band-reject properties.
Abstract: This paper deals with a single-input multipleoutput biquadratic filter providing three functions (lowpass, high-pass and band-pass) based on voltage differencing differential input buffered amplifier (VD-DIBA). The quality factor and pole frequency can be electronically tuned via the bias current. The proposed circuit uses two VD-DIBAs and two grounded capacitors without any external resistors, which is suitable to further develop into an integrated circuit. Moreover, the circuit possesses high input impedance, providing easy voltage-mode cascading. It is shown that the filter structure can be easily extended to multi-input filter without any additional components, providing also all-pass and band-reject properties. The PSPICE simulation results are included, verifying the key characteristics of the proposed filter. The given results agree well with the theoretical presumptions.
TL;DR: In this article, a new current transformer (CT) saturation detection and compensation algorithm is proposed, which depends on a saturation detection index (D n ) which is derived by using the derivatives of the current signals and Newton's backward difference formulae.
Abstract: This study presents a new current transformer (CT) saturation detection and compensation algorithm. The proposed algorithm depends on a saturation detection index ( D n ) which is derived by using the derivatives of the current signals and Newton's backward difference formulae. The calculated index is continuously compared with an adaptive threshold ( T h ) to estimate the start and the end point of CT saturation. A low-pass first-order Butterworth filter is used to suppress noise and harmonics which may be present in CT secondary current. The proposed saturation detection algorithm has been tested by considering different values of remanent flux, fault type, fault inception angle, burden resistance, decaying DC component of fault current and noise. At the same time, modified discrete Fourier transforms-based compensating algorithm has also been proposed to reconstruct the saturated samples. Validation of the proposed scheme is also performed on a developed laboratory prototype. A comparative evaluation of the proposed algorithm is also performed with the existing schemes. A series of test results from the simulation software and the laboratory prototype show the effectiveness of the proposed scheme.
TL;DR: A compact nano-power fourth-order bandpass filter operating from a 0.5 V supply, with an adjustable center frequency ranging from 125 Hz to 16 kHz, is presented, leading to best figure of merit achieved when compared to other existing designs to date.
TL;DR: An attempt has been made to design a low-pass linear-phase multiplier-less finite duration impulse response (FIR) filter using differential evolution (DE) algorithm to search the impulse response coefficients of the FIR filter in the form of sum of power of two (SPT) in order to avoid the multipliers during design process.
Abstract: Evolutionary computational techniques have been employed judiciously in various signal processing applications of late. In this paper, such an attempt has been made to design a low-pass linear-phase multiplier-less finite duration impulse response (FIR) filter using differential evolution (DE) algorithm. This particular evolutionary optimization technique has been explored to search the impulse response coefficients of the FIR filter in the form of sum of power of two (SPT) in order to avoid the multipliers during design process. The performance of the designed low-pass filter has been studied thoroughly in terms of its frequency characteristics and primitive requirement of fundamental hardware blocks. The superiority of our design has been ascertained over a number of existing techniques by various means. Finally, the proposed filter of different lengths has been implemented on a field programmable gate array (FPGA) chip for evaluating the competency of this work. The percentage improvement in hardware complexity produced by our design has also been computed and clearly listed in this paper for convenience.
TL;DR: In this article, a dual-mode structure is proposed to reject unwanted resonances, producing a widely separated dual-band response, and a four-pole filter with two distinct modes is proposed.
Abstract: A novel and compact design of a dual-band filter with widely separated passbands is proposed. Applications of such a device can be found in systems where a single device is responsible for both transmission and reception. The proposed filter is composed of resonators working on two distinct modes. The proposed dual-mode structure offers a good rejection of unwanted resonances, producing a widely separated dual-band response. The idea is demonstrated with the design of a four-pole filter comprising two dual-mode structures and the concept is verified experimentally by the measurement of a fabricated prototype. Finally, a six-pole filter is proposed, showing the possibility of designing higher order filters.
TL;DR: In this article, a triple-passband filter with high passband selectivity and compact circuit size is presented, which includes two multipath-embedded stepped impedance resonators connected with magnetically coupling by via hole technique at the symmetric plane of the filter.
Abstract: This letter presents a new resonator configuration to design a triple-passband filter with high passband selectivity and compact circuit size. The filter includes two multipath-embedded stepped impedance resonators (SIRs), connected with magnetically coupling by via hole technique at the symmetric plane of the filter. The multipath-embedded SIR is designed at 1.575, 2.45, and 3.5 GHz. The resonant frequencies can be easily controlled by tuning impedance ratio K i and length ratio αi (where i = 1, 2, and 3) of the multipath-embedded SIR. This study provides an effective method to easily design the triple-passband filter with compact circuit size, high passband selectivity and low insertion loss.
TL;DR: For the low-pass filter application, the proposed circuit outperforms a seventh-order Butterworth filter while their circuit sizes are comparable and may potentially enhance the degree of integration in RF and microwave systems.
Abstract: Among many microstrip configurations, the open-circuited shunt stub is probably the most common and versatile one. It is capable of performing a wide range of functions. Despite extensive studies and applications of the open-circuited shunt stub, comparatively little is known about aperiodic stubs on a microstrip line. In this paper, aperiodic stubs on a microstrip line are exploited to implement a high-performance low-pass filter and a joint design of the artificial transmission line and low-pass filter. The experimental results validate the performance of the proposed circuits. For the low-pass filter application, the proposed circuit outperforms a seventh-order Butterworth filter while their circuit sizes are comparable. For the joint design, it may potentially enhance the degree of integration in RF and microwave systems.
Patent•
14 Mar 2014
TL;DR: In this article, a method of designing an acoustic microwave filter in accordance with frequency response requirements is proposed, which comprises selecting an initial filter circuit structure including a plurality of circuit elements comprising at least one resonant element and at least another reactive circuit element.
Abstract: A method of designing an acoustic microwave filter in accordance with frequency response requirements. The method comprises selecting an initial filter circuit structure including a plurality of circuit elements comprising at least one resonant element and at least one other reactive circuit element, selecting circuit response variables based on the frequency response requirements, selecting a value for each of the circuit elements based on the selected circuit response variables to create an initial filter circuit design, transforming the resonant element(s) and the other reactive circuit element(s) of the initial filter circuit design into at least one acoustic resonator model to create an acoustic filter circuit design, adding parasitic effects to the acoustic filter circuit design to create a pre-optimized filter circuit design, optimizing the pre-optimized filter circuit design to create a final filter circuit design, and constructing the acoustic microwave filter based on the final filter circuit design.
TL;DR: In this paper, a new scheme based on the fractional Fourier transform (FrFT) in time frequency domain was proposed to mitigate noise in seismic data, where the residual noises after frequency filtering are with the same frequencies with the filtered seismic signals.
01 Jun 2014
TL;DR: In this article, a bandstop filter architecture with small form factor and very large attenuation over an octave frequency tuning range is demonstrated, which provides a benefit of resonator-Q-independent zero reflection coefficient at the center frequency, and is demonstrated with a tuning range of 5504 to 13334 MHz varactor-tuned two-resonator notch filter with minimum notch attenuation.
Abstract: A bandstop filter architecture with small form factor and very large attenuation over an octave frequency tuning range is demonstrated The architecture provides a benefit of resonator-Q-independent zero reflection coefficient at the center frequency, and is demonstrated with a tuning range of 5504 to 13334 MHz varactor-tuned two-resonator notch filter with minimum notch attenuation of 64 dB, 3-dB fractional bandwidth (FBW) of 1086% to 322% over the tunable frequency range and passband up to 3565 MHz, resulting in a 648-to-1 upper passband, in a footprint of 227×165 cm
2
The unloaded quality factor (Q-factor) was extracted to be 62 at 13334 MHz
TL;DR: In this paper, a novel class of selective CIC (Cascaded-Integrator-Comb) filters given insertion loss specification is presented, where the goal is to choose the free integer filter parameters such that the filter function yields a desired frequency response.
Abstract: The aim of this letter is to provide graphs which can be used to design a novel class of selective CIC (Cascaded-Integrator–Comb) filters given insertion loss specification. The goal is to choose the free integer filter parameters such that the filter function yields a desired frequency response. To determine the filter parameters needed to satisfy the desired specifications, one can use the graphs of normalized passband and stopband cut-off frequencies versus filter order N . Two graphs, one for maximum attenuation in the passband and one for minimum attenuation in the stopband, are given here. Achieved improvement of performances of the novel class of CIC filter functions over the classical CIC filters is also given. In case of N = 7, the novel class of CIC filter functions gives improvements of 27.68 dB, 47.29 dB and 66.53 dB for different values 1, 2 and 3 of free parameter L , respectively.
01 Jan 2014
TL;DR: Chronux, an open-source software package written in MATLAB®, which can be used to analyze neural data, is introduced, which will look at encoding and decoding by making use of frequency analysis.
Abstract: Here we will examine the local field potential. We will also look at encoding and decoding by making use of frequency analysis. Finally, we will introduce Chronux, an open-source software package written in MATLAB®, which can be used to analyze neural data.
TL;DR: An approach of gradient pulsing using a spiral line is implemented and spirals are generated by applying single-frequency cosine and sine waves of slowly varying amplitudes to the X and Y-axes of the AFM's piezoelectric tube scanner (PTS).
Abstract: This paper demonstrates a high-speed spiral imaging technique for an atomic force microscope (AFM). As an alternative to traditional raster scanning, an approach of gradient pulsing using a spiral line is implemented and spirals are generated by applying single-frequency cosine and sine waves of slowly varying amplitudes to the X and Y-axes of the AFM’s piezoelectric tube scanner (PTS). Due to these single-frequency sinusoidal input signals, the scanning process can be faster than that of conventional raster scanning. A linear quadratic Gaussian controller is designed to track the reference sinusoid and a vibration compensator is combined to damp the resonant mode of the PTS. An internal model of the reference sinusoidal signal is included in the plant model and an integrator for the system error is introduced in the proposed control scheme. As a result, the phase error between the input and output sinusoids from the X and Y-PTSs is reduced. The spirals produced have particularly narrow-band frequency measures which change slowly over time, thereby making it possible for the scanner to achieve improved tracking and continuous high-speed scanning rather than being restricted to the back and forth motion of raster scanning. As part of the post-processing of the experimental data, a fifth-order Butterworth filter is used to filter noises in the signals emanating from the position sensors and a Gaussian image filter is used to filter the images. A comparison of images scanned using the proposed controller (spiral) and the AFM PI controller (raster) shows improvement in the scanning rate using the proposed method.
TL;DR: In this paper, a new compact microstrip lowpass filter with sharp roll-off and ultrawide stopband using funnel and triangular patch resonators is presented, and the experimental results show a good agreement with the simulated results and demonstrate that, the sharp rolloff and good stopband performance is obtained by the proposed filter.
Abstract: This article presents a new compact microstrip lowpass filter with sharp roll-off and ultrawide stopband using funnel and triangular patch resonators. The patch resonators are placed symmetrically about a high impedance central microstrip line. The filter has been designed and fabricated using a very low cost material. The experimental results show a good agreement with the simulated results and demonstrate that, the sharp roll-off and good stopband performance is obtained by the proposed filter. The 3 dB cutoff frequency of the proposed filter is at 5.55 GHz with a roll-off of 84 dB/GHz and its stopband extends up to 11.8 GHz. The filter has an ultra compact size of 9.4 × 8 mm2. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2534–2536, 2014