Showing papers on "Butterworth filter published in 2003"

General Model-Based Filters for Extracting Cycles and Trends in Economic Time Series

Abstract: A class of model-based filters for extracting trends and cycles in economic time series is presented These lowpass and bandpass filters are derived in a mutually consistent manner as the joint solution to a signal extraction problem in an unobserved-components model The resulting trends and cycles are computed in finite samples using the Kalman filter and associated smoother The filters form a class which is a generalization of the class of Butterworth filters, widely used in engineering They are very flexible and have the important property of allowing relatively smooth cycles to be extracted from economic time series Perfectly sharp, or ideal, bandpass filters emerge as a limiting case Applying the method to quarterly series on US investment and GDP shows a clearly defined cycle

A compact second-order LTCC bandpass filter with two finite transmission zeros

Abstract: A novel implementation and associated design formula for a compact low-temperature cofired ceramics (LTCC) lumped-element second-order bandpass filter are proposed in this paper. The filter schematic that provides two finite transmission zeros is well known. It is shown in the paper that the filter schematic is built on a pair of conventional inductive coupled resonator tanks with a feedback capacitor between input and output. While revealing its working mechanism both graphically and mathematically, a simple design procedure for such a compact filter is also given. The proposed filter has been implemented in a six-layer ceramic substrate using LTCC technology, showing promising application potentials in miniaturized mobile terminals and Bluetooth RF front-ends. The measured results agree very well with the full-wave electromagnetic designed responses.

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.

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.

Comparisons in circuit configuration and filtering performance between hybrid and pure shunt active filters

Abstract: This paper deals with a hybrid shunt active filter for harmonic compensation of a three-phase diode rectifier in a 480-V adjustable-speed drive system. The hybrid filter is formed by a three-phase single-tuned current LC filter for the 7-th harmonic frequency and a small-rated three-phase voltage-source PWM inverter. Computer simulation is carried out to compare the hybrid filter with a pure shunt active filter in terms of circuit configuration and filtering performance. The simulation results indicate effectiveness and viability of the hybrid filter. In addition, theoretical analysis confirms the validity of the simulation results.

Digital filter adaptively learning filter coefficient

Abstract: A linear filter feeds back an error signal generated using the output of an adaptive filter to a learning circuit. The learning circuit learns the coefficients of the adaptive filter using the error signal. The coefficients of the linear filter are determined depending on the generation method of a target signal for error minimization. In a signal interpolation type timing recovery digital filter, the coefficients of an inverse interpolation filter are determined in such a way as to minimize an error of a signal after interpolation.

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

Bandwidth and central frequency control on tunable bandpass filter by using MEMS cantilevers

Abstract: This paper deals with a tunable bandpass filter topology which controls independently and simultaneously both the central frequency and bandwidth. This tunable filter results from the association of MEMS cantilevers, used as variable capacitors, with an original passive topology. The latter is based on dual behavior resonators (DBRs), each of them is constituted of low- and high-frequency open-ended stubs. The associated filter electrical response is characterized by tunable frequency transmission zeros. A millimeter bandpass filter with central frequency and relative bandwidth tunability of about 10 and 75%, respectively, is presented.

Wideband monolithic tunable high-Q notch filter for image rejection in RF application

Abstract: A notch filter with a high Q factor, which is integrated with a first and a second cascoded LNA, is totally contained on an integrated chip. The notch filter, comprising two Q-enhancement circuits, is coupled to the second differential LNA. The two Q-enhancement circuits are combined to generate sufficient negative impedance to compensate for the loss in the on-chip low Q inductors. To improve the image rejection of the notch filter in a wide frequency band, the notch filter uses an automatic current tuning circuit which consists of an analog multiplier and fixed and voltage controlled current sources. Furthermore, by modifying the connection and location of the tunable varactor, another wideband tunable notch filter is implemented. The notch filter can be applied in all current wireless receiver systems.

A 1.5-V 75-dB dynamic range third-order G/sub m/-C filter integrated in a 0.18-/spl mu/m standard digital CMOS process

Abstract: A design methodology of a CMOS linear transconductor for low-voltage and low-power filters is proposed in this paper. It is applied to the analog baseband filter used in a transceiver designed for wireless sensor networks. The transconductor linearization scheme is based on regulating the drain voltage of triode-biased input transistors through an active-cascode loop. A third-order Butterworth low-pass filter implemented with this transconductor is integrated in a 0.18-/spl mu/m standard digital CMOS process. The filter can operate down to 1.2-V supply voltage with a cutoff frequency ranging from 15 to 85 kHz. The 1% total harmonic distortion dynamic range measured at 1.5 V for 20-kHz input signal and 50-kHz cutoff frequency is 75 dB, while dissipating 240 /spl mu/W.

An ultra-narrowband HTS bandpass filter

Abstract: This paper presents the measured results of an HTS ultra-narrowband bandpass filter with a 100 kHz bandwidth. This filter, with a fractional bandwidth of 0.014% and a center frequency of 700 MHz, represents a previously unrealized portion of filter parameter space. This filter was realized using a five-pole Chebyshev filter design and was fabricated using an HTS microstrip configuration. This filter required very high Q, very weak coupling, and a strong reduction in parasitics. Unloaded Qs of 135,000 were achieved with a resulting insertion loss of 1.37 dB. Even resonator Qs of 20,000 would lead to a filter loss of 9 dB. A noise figure of 1 dB was achieved for a complete system with this filter and a cryogenic low-noise amplifier.

Tunable allpass filter for low voltage operation

Abstract: A novel high-performance first-order allpass filter with electronically adjustable filter parameters is presented. The core of the circuit is an inverting unity gain amplifier with electronically adjustable output resistance, which leads to an allpass filter realisation with tunable time constant. The circuit is composed of a simple CMOS cascode circuit and a level shifter and is also very suitable for low voltage operation, since it employs two active devices between its rails. SPICE simulation and experimental results verifying theoretical analyses are also given.

A low noise vector modulator with integrated basebandfilter in 120 nm CMOS technology

Abstract: A low noise vector modulator for cellular systems with integrated baseband filter has been developed in 120 nm CMOS technology. The baseband filter is an anti-aliasing filter for the digital to analogue converter of the baseband that has been build around a differential amplifier with 3/sup rd/ order butterworth low pass characteristic. High linearity and low output noise can be achieved for the modulator due to the current interface between the baseband filter and the mixer cells. The GSM specification for emitted noise into the receive band can be fulfilled without using a duplex filter behind the power amplifier output.

Ultra selective HTS bandpass filter for 3G wireless application

Abstract: This paper presents an ultra selective HTS filter that meet existing 3G wireless band. The filter consists of 22 resonators and five cross coupling structures that produce ten transmission zeros near the band edges. A quadruplet cross coupling technique was introduced into the design for the transmission zero implementation. To accommodate twenty-two resonators within a limited wafer size, a compact new topological resonator was also developed. The filter was fabricated using a YBCO thin film on a 2-in MgO wafer. Measured skirt slope has exceeded 30 dB/100 kHz and the filter has a 90 dB out-of-band rejection at 350 kHz from its band edge. This filter surpasses the rejection of an ideal 50-pole Chebyshev filter.

Filter set for frequency analysis

Abstract: A system and method are disclosed for analyzing an input signal (100) into a plurality of frequency components. In one embodiment, the input signal (100) is processed with a first set of low pass filters (102-132) to derive a first set of frequency components wherein the first set of low pass filters (102-132) are arranged serially in a chain having a first low pass filter (102) and a last low pass filter (132), the output of each low pass filter being fed to the next low pass filter in the chain until the last low pass filter (132). The output of the last low pass filter (132) is downsampled (140) to produce a downsampled signal. The downsampled signal is processed with a second set of low pass filters (142-172) to derive a second set of frequency components.

FPGA realization of multipurpose FIR filter

Abstract: A multipurpose FIR filter has been designed and realized by field programmable gate arrays (FPGA) for real-time filtering applications. The design can accomplish an arbitrary filter frequency response and variable filter order up to 127. The coefficients are computed through the Hamming windowing technique. The model is capable of performing filtering operations, like lowpass, highpass, bandpass and bandstop based on selection that is embedded into the design. The filter is set to 8-bit signed data processing. Linear constant coefficient difference equation (LCCDE) has been used to filter the input data in time domain. The design is coded with VHDL to cope with the parallelism of digital hardware. Simulation, compilation and synthesis have been done to verify the validity of the design outputs. To test the correctness of the design the observed output is compared with the calculated output results from MATLAB implementation that confirms the effectiveness of the design.

Subband all-pass filter architectures with applications to dispersion and dispersion-slope compensation and continuously variable delay lines

Abstract: A new optical filter architecture is proposed that employs optical subband and all-pass filters but circumvents the typical tradeoff between passband width and peak delay inherent to all-pass filters. A filter design for a dispersion compensator with a tuning range of /spl plusmn/1000 ps/nm and 95-GHz passband width on a 100-GHz grid is presented. Compared with a cascade architecture, a lower core-to-cladding index contrast for planar waveguide ring resonator implementations can be used, and lower filter losses are achieved, since the signal propagates through fewer all-pass filter stages for the same dispersion. A continuously variable delay line is designed with more than 90% bandwidth utilization. For a ten-stage all-pass filter with 25-GHz free spectral range (FSR) in a double-pass configuration, a 1000-ps continuous tuning range can be achieved. Finally, a dispersion-slope compensator design is presented with a change in dispersion of 700 ps/nm over a wavelength range determined by the filter FSR-to-channel-spacing ratio.

Surface acoustic wave duplexer and communication apparatus having the same

Abstract: A surface acoustic wave duplexer includes a first filter including a ladder filter and a second filter including a ladder filter with a pass band that is different from that of the first filter. Inductors are connected in parallel with respective series resonators of both first and second filters.

Digital pre-distortion for the linearization of power amplifiers with asymmetrical characteristics

Abstract: An input signal is pre-distorted to reduce spurious emissions resulting from subsequent signal amplification. Frequency-dependent pre-distortion is preferably implemented in combination with frequency-independent pre-distortion, where the frequency-dependent pre-distortion corresponds to amplifier distortion that has a magnitude that is proportional to the frequency offset from the carrier frequency and a ±90° phase shift on either side of the carrier frequency. The frequency-dependent pre-distortion is generated by differentiating waveforms corresponding to two different sets of pre-distortion parameters with respect to time. In one embodiment, one of the differentiated waveforms is applied to a positive-frequency filter and the other to a negative-frequency filter to generate positive- and negative-frequency pre-distortion signals, respectively, to account for asymmetries in the amplifier characteristics. In another embodiment, only one of the differentiated waveforms is applied to an asymmetric filter (i.e., either a positive-frequency filter or a negative-frequency filter).

Multiple-coupled microstrip hairpin-resonator filter

Abstract: This letter presents the design of six-resonator multiple-coupled microstrip filter. A low-pass prototype of six-resonator multiple-coupled filter is developed first based on the conventional Chebyshev filter. The characteristics of attenuation poles located on both sides of the frequency response are described. According to the low-pass prototype, the design of a six-resonator multiple-coupled microstrip hairpin filter at 6 GHz is completed with the aid of EM simulation. The experimental results are demonstrated and discussed.

On the design of high-linear and low-noise two-branch channelized active bandpass filters

Abstract: A novel systematic and consistent method for two-branch channelized active bandpass filter design is presented. The design technique is obtained starting from a rigorous and detailed theoretical analysis of this type of filter, undeveloped to date. In the proposed method, the values of key design parameters are established directly from the initial specifications by using a simple set of design formulas. The design procedure is validated with construction and measurement of a specific two-branch channelized filter prototype at 2.5 GHz in microstrip technology. Other relevant factors in active filter design techniques, such as nonlinear and noise performance, are also considered in the experimental characterization of the filter prototype.

A windowing approach for designing critically sampled nearly perfect-reconstruction cosine-modulated transmultiplexers and filter banks

Abstract: A very fast technique for designing nearly perfect-reconstruction (NPR) critically sampled cosine-modulated M-channel transmultiplexer (TMUX) and filter bank (FB) systems is proposed. This technique is based on using the windowing technique for designing the prototype filter so that its 3-dB cutoff frequency is located at /spl omega/=/spl pi//(2M). The motivation for this is the observation that if the prototype filter cascaded with itself is a 2Mth filter, then the resulting TMUX (in the case of an ideal channel being a pure delay) or FB system has approximately a perfect-reconstruction (PR) property. This implies that for this cascade the 6-dB cutoff point should be approximately located at /spl omega/=/spl pi//(2M), and, correspondingly, the 3-dB cutoff frequency of the prototype filter is located at this angular frequency. The main advantage of the proposed design scheme is that it significantly lowers the computational complexity when compared with other existing techniques proposed for designing critically sampled cosine-modulated TMUX or FB systems. The PR property is not achieved, but for the resulting TMUX (FB) systems, the intersymbol interference and crosstalk errors (the amplitude and alias errors) are small. Both of these errors are small enough in practical systems. Several examples are included illustrating these desired properties.

A fully differential CMOS integrated 4th order reconfigurable GM-C lowpass filter for mobile communication

Abstract: A fully reconfigurable channel select filter is presented which is used as a part of a multi mode direct conversion receiver. The filter supports different modes including GSM, IS-95, and UMTS. A 4/sup th/ order Butterworth filter is realized in a g/sub n/ C filter topology. The filter circuit is implemented in a standard 0.35 /spl mu/m CMOS process. The filter is able to handle large input signals up to 600mVpp at a supply voltage of 2.7V. The circuit has a low current consumption of 620/spl mu/A, whereas the needed die size is only 530520/spl mu/m.

A low voltage second order biquad using pseudo floating-gate transistors

Abstract: We present a low-voltage/low power second order filter. The filter consists of 6 pseudo floating-gate transistors operated in weak inversion. The filter is suitable for any kind of application requiring low frequency ranges, such as biomedical products. An electronic cochlea consisting of replicas of the filter is presented. The filter operates at a supply voltage below 1 V, consumes power down to 5 nW, and has a harmonic distortion suppression of -60 dB.

Current-mode active-only universal filter

Abstract: A new current-mode active-only universal filter based on and employing two OA's and three DOOTAs is presented. The circuit is capable of realizing all the five generic filter characteristics viz. Lowpass, bandpass, highpass, notch and allpass without changing the circuit topology or nature of components, or additional component besides, no component matching conditions is required. The filter parameters ω 0 and Q are electronically tunable in an orthogonal manner through separate transconductances of OTAs. The circuit has low sensitivity performance and is ideal for production in IC form as it is devoid of external passive components.

Optimizing the design of IIR filter via genetic algorithm

Abstract: The IIR filter design under the mixed-criterion of H/sub 2/ norm and /spl infin/ norm is proposed in this paper, and genetic algorithms (GA) is introduced to realize the filter design based on such criterion. By this approach, the disadvantage of other conventional methods is avoided and the satisfied performance of the designed filter is obtained. The evaluating example shows that the filter designed by GA is superior to conventional Butterworth filter in either the optimization capability of design method or the performance of designed filter.

Cross-coupled dual-spiral high-temperature superconducting filter

Abstract: A microstrip bandpass filter implemented with dual-spiral resonators is described in this letter. The dual-spiral resonators make the filter compact and allow implementation of positive and negative inter-resonator couplings. Implementation of the positive and negative couplings is used to introduce a pair of finite frequency transmission-zeros in the filter response. The two zeros are designed to be close to the passband, thus improving the selectivity of the filter. As an example, a four-stage cross-coupled dual-spiral filter is designed and fabricated using superconducting YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films deposited on LaAlO/sub 3/ substrate.

Quantized FIR filter design using compensating zeros

Abstract: This article presents a design method for translating a finite impulse response (FIR) floating-point multiplierless filter design. Conventional wisdom dictates that finite word-length (i.e., quantization) effects can be minimized by dividing a filter into smaller, cascaded sections. In this design method, it is shown how to quantize the cascaded sections so that the finite word-length effects in one section are guaranteed to compensate for the finite word-length effects in the other section. This simple method called, "compensating zeros," ensures that: (1) the quantized filter's frequency response closely matches the unquantized filter's frequency response (in both magnitude and phase); and (2) the required hardware remains small and fast.

Fast characterization of the noise bounds derived from coefficient and signal quantization

Abstract: This paper presents a new method for computing the absolute noise bounds caused by quantization of coefficients and signals in fixed-point implementation of digital filters. A tool based on refined interval-based computations has been enhanced to calculate with reduced computational cost the implications of both effects in the finite wordlength behavior of the specific realizations. Finally, a particular filter realization is quantized using different wordlengths and the computed bounds are presented for comparison.