Showing papers on "Voltage-controlled filter published in 2014"

A Novel Design and Optimization Method of an $LCL$ Filter for a Shunt Active Power Filter

Abstract: Compared with the L filter, the LCL filter is more suitable for high-power low-switching-frequency applications due to its better attenuation characteristics on high frequencies. However, the parameter design for the LCL filter is more complex since both the inhibiting effect of the high-frequency harmonic current and the influence to the controller response performance of the converter should be considered. In this paper, the model of the LCL filter and the design criteria of the LCL filter for a shunt active power filter (SAPF) are analyzed in the beginning. Then, the impacts of all parameters of the LCL filter on SAPF are intuitively drawn on a graph by theoretical derivation. Finally, a novel parameter design and optimization method for the LCL filter is proposed. The validity and effectiveness of the proposed method are proved by simulated and experimental results of a single-phase SAPF prototype at the end of this paper.

An LTCL Filter for Three-Phase Grid-Connected Converters

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.

Analysis and Design of a High-Order Discrete-Time Passive IIR Low-Pass Filter

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.

Analysis and Modeling of a Gain-Boosted N-Path Switched-Capacitor Bandpass Filter

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].

Improving High-Frequency Performance of an Input Common Mode EMI Filter 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.

0.73–1.03-GHz Tunable Bandpass Filter With a Reconfigurable 2/3/4-Pole Response

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.

CMOS Compatible Reconfigurable Silicon Photonic Lattice Filters Using Cascaded Unit Cells for RF-Photonic Processing

Abstract: This paper presents an overview of a complementary metal-oxide-semiconductor-compatible, programmable, analog optical lattice filter based on silicon unit cells arrayed in large-scale photonic integrated circuits. The unit cell employs a combination of a ring resonator and a Mach-Zehnder interferometer with tunable phase elements in both of the paths. Each proposed unit cell contributes a separately controllable pole and zero pair. Under various configurations, we experimentally achieved >60-dB two-tone spurious-free dynamic range. For more sophisticated signal processing, we experimentally demonstrated an optical lattice filter with four cascaded unit cells capable of dynamically reconfiguring between a bandpass filter and a notch filter. The reconfiguration of the unit-cell and four-cell silicon lattice filter is based on a recursive algorithm, which brings new possibilities to RF photonic processing and a wide range of applications with design scalability to a large number of poles and zeros. The experimental results and the recursive algorithms show potentials for scaling to higher order filter designs.

Removal of high frequency noise from ECG signal using digital IIR butterworth filter

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.

Tunable active filters for rf and microwave applications

Abstract: In this paper, we present a low-voltage tunable active filter for microwave applications The proposed filter is based on a single-transistor active inductor (AI), that allows the reduction of circuit area and power consumption The three active-cell bandpass filter has a 1950 MHz center frequency with a -1 dB flat bandwidth of 10 MHz (Q ≈ 200), a shape factor (30–3 dB) of 25, and can be tuned in the range 1800–2050 MHz, with constant insertion loss A dynamic range of about 75 dB is obtained, with a P1dB compression point of -5 dBm The prototype board, fabricated on a TLX-8 substrate, has a 4 mW power consumption with a 12 V power supply voltage

Low-Complexity Reconfigurable Fast Filter Bank for Multi-Standard Wireless Receivers

Abstract: This brief presents a new low-complexity reconfigurable fast filter bank (RFFB) for wireless communication applications such as spectrum sensing and channelization. In RFFB, the bandwidth and center frequency of sub-bands can be varied with high frequency resolution without hardware reimplementation. This is achieved with an improved modified frequency transformation-based variable digital filter (MFT-VDF) at the first stage of the proposed multistage implementation. Existing second-order frequency transformation-based low-pass VDFs have limited cutoff frequency range which is approximately 12.5% of the sampling frequency. The proposed low-pass MFT-VDF offers unabridged control over the cutoff frequency on a wide frequency range thereby, improving the cutoff frequency range of existing VDFs. The design example shows that the RFFB is easy to design and offers substantial savings in gate counts over other filter banks.

A Dual-Band Bandpass Filter With Widely Separated Passbands

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.

Electronically controlled high input and low output impedance voltage mode multifunction filter with grounded capacitors

Abstract: In this study, a three-input single-output voltage-mode biquadratic filter employing voltage differencing differential input buffered amplifier (VD-DIBA) is presented. The proposed filter uses two VD-DIBAs and two grounded capacitors without any external resistors, which is well suited for integrated circuit implementation. The circuit provides five standard transfer functions, namely, low pass, high pass, band pass, notch and all pass filters with electronic control of quality factor and pole frequency. Each transfer function can be selected by suitably selecting input signals via digital method. The filter does not require inverting of the input voltage signal. Moreover, the circuit possesses high input and low output impedances and thus it enables simple voltage-mode cascading. The PSPICE simulation and also experimental results are included, verifying the workability of the proposed filter. The given results agree well with the theoretical anticipation.

Improving Dynamic Response of Active Harmonic Compensator Using Digital Comb Filter

Abstract: Harmonic extraction and control is one of the main elements in active power filter design. The advances in the digital signal processor (DSP)-based control have facilitated the use of sophisticated filters and control techniques to achieve better dynamic performance, which was difficult earlier with the use of analog design. To improve the dynamic response of the active harmonic controller, we propose a comb-filter-based solution, which can be implemented on a DSP platform. Performance evaluation results for the load transient show a substantial improvement in the dynamic performance of the harmonic compensator compared with the conventional low-pass-filter-based approaches.

Active And Passive Analog Filter Design

Abstract: active high pass filter op amp high pass filterbasic, design parameters of an anti aliasing filter in this sec tion aliasing theory will be discussed this will be fol lowed by operational amplifier filter circuits examples of active and passive low pass filters will also be dis cussed finally a 12 bit circuit design example will be given all of the active analog filters discussed in this, p bruschi analog filter design 10 passive network includes only passive components resistors capacitors inductors transformers when connected to external independent sources the net energy flux into the network is always positive passive network active network, filters active amp passive introduction filters pervade electronic design as there is always a need to shape the frequency response of signals propagating through the system of interest to achieve the correct shaping one considers the fourier transform of the filter and designs it so that the magnitude of this transform has the desired shape in, we can also divide filters by the singal processing method analog filters work on real continuous signals and digital filters work on sampled quantitized filtres analog filters can be passive consisting of passive elements only resistors capacitors and coils

Linear-Phase VDF Design With Unabridged Bandwidth Control Over the Nyquist Band

Abstract: This brief presents a low-complexity linear-phase variable digital filter (VDF) design with tunable lowpass (LP), highpass (HP), bandpass (BP), and bandstop (BS) responses anywhere over the entire Nyquist band. The spectral-parameter-approximation-based VDFs (SPA-VDFs) was designed using the Farrow structure and has advantages of linear phase, lower group delay, and fewer variable multipliers. However, the total gate count and the dynamic range of filter coefficient values of SPA-VDFs significantly increase with the tunable range of cutoff frequency, which limits their usefulness in emerging signal processing and wireless communication applications. In addition, existing VDFs need to update either filter coefficients or need parallel filter structures to obtain variable LP, HP, BP and BS responses. In this brief, a new VDF design is proposed by deftly integrating SPA-VDF with the modified coefficient decimation method (MCDM), and it will be referred to as SPA-MCDM-VDF. The SPA-MCDM-VDF provides LP, HP, BP, and BS responses with unabridged center frequency and bandwidth control over the entire Nyquist band without the need for hardware reimplementation or coefficient update. The complexity comparisons show that the SPA-MCDM-VDF offers substantial savings in gate count, group delay, and number of variable multiplications over other linear-phase VDFs.

Quad-band bandpass filter design by embedding dual-band bandpass filter with dual-mode notch elements

Abstract: A quad-band bandpass filter of compact dimensions by embedding several dual-mode notch elements into a stub-type dual-band bandpass filter is presented, and the four passbands are achieved by splitting the two passbands of the dual-band bandpass filter with two notch bands generated by the dual-mode notch elements. A prototype filter with passbands located at 1.4–1.7, 2.1–2.3, 3.3–3.6 and 5.2–5.4 GHz is designed with the help of optimisation methods. Good agreement between simulations and measurements are achieved, demonstrating good features such as controllable and wide bandwidths, higher filter order, compact dimensions and high isolations.

A GNSS interference identification using an adaptive cascading IIR notch filter

Abstract: A low-complexity time-domain approach for global navigation satellite systems is proposed to detect and identify single-tone, multi-tone, swept continuous wave interference (CWI) and band-limited white Gaussian noise (BLWN). An adaptive notch filter and adaptive cascading filter structure are employed to identify the type of interference signals. The number of the cascading stages is selected by comparing the total power in receiver bandpass, and after, passing the adaptive notch filter. For this reason, the proposed filter structure is more efficient in identifying and mitigating interference signals than the conventional filter structure. In addition, the automatic gain control gain is used to detect the existence of continuous wave interference. The performance of the interference detection and identification method is evaluated for the cases of GPS signal in the presence of single-tone, multi-tone, swept CWI and BLWN.

Digitally-programmable fully-differential current-mode first-order LP, HP and AP filter sections

Abstract: Analog signal processing in the current-mode regime offers several advantages over its voltage-mode counterpart. Although, current-mode circuits exhibit better noise performance, fully-differential topologies may be employed to improve the noise cancellation,on account of their common-mode rejection properties. This paper presents fully-differential, first-order, low-pass, high-pass and all-pass filter sections operating in current-mode. The recently introduced Digitally Controllable Differential Voltage Current Conveyor (DC-DVCC) has been chosen as the active building block. Programmability of the filter characteristics through a digital control word is demonstrated.

Adaptive pre-equalization in optical communications

Abstract: The filter estimate produced by post-equalization processing of an optical signal at a receiver is used to generate pre-equalizer filter coefficients that are communicated back to the source of the optical signal for performing pre-equalization. In one advantageous aspect, the already existing post-equalization modules of an optical receive equipment can thus be used to produce, in addition, a pre-equalizer filter for use by the source side.

Hairpin microstrip bandpass filter for millimeter-wave applications

Abstract: A compact microstrip bandpass filter is proposed in this paper for millimeter-wave applications. The filter consists of three new non-uniform coupled-line modified hairpin resonators. The filter is designed to exhibit a fractional bandwidth of about 5.0 % at a center of frequency of approximately 34 GHz. The shapes of the hairpin resonators are modified to suppress the unwanted spurious harmonic response. As a result, the filter exhibits very wide stopband with a rejection level better than 10-dB. In addition, the filter shows a transmission zero close to upper edge of the desired passband which enhances the selectivity of the passband. The filter design is successfully realized on a RT/Duroid 6002 with a dielectric constant of 2.94 and a thickness of 127μm. The filter is simulated, and fabricated to demonstrate the proposed technique where excellent agreement is obtained.

Lna with linearized gain over extended dynamic range

Abstract: A low noise amplifier including a variable gain amplifier stage configured to accept an input signal and to provide a load driving signal; a tunable bandpass filter connected as a load to the variable gain amplifier stage, wherein the bandpass filter includes a cross-coupled transistor pair, and at least one cross-coupled compensation transistor pair biased in a subthreshold region configured to add a transconductance component when the load driving signal is of a magnitude large enough to decreases a transconductance of the cross-coupled transistor pair; and, a controller circuit configured to tune the bandpass filter. The filter can be tuned in respect to the frequency and the quality factor Q.

Voltage-mode multifunction filter with mutually independent Q and ω 0 control feature using VDDDAs

Abstract: The paper focuses on the application possibilities of the newly presented voltage differencing active building block called voltage differencing differential difference amplifier. Using this active element, a multifunction frequency filter is designed featuring the possibility of mutually independent control of quality factor Q and characteristic frequency $$\omega _0$$ ? 0 by means of active elements. The structure of the filter is based on the idea of the Akerberg-Mossberg (AM) filter, i.e. the integrators in the structure are always realized only by two active elements. This fact results in better phase compensation for the filter. Compared to the AM opamp based filter, the newly proposed structure features high-impedance inputs, low-impedance output, and all basic frequency responses. The performance of the proposed structure has been verified by SPICE simulations using the TSMC $$0.18\,\upmu \hbox {m}$$ 0.18 μ m level-7 SCN018 CMOS process parameters with $$\pm 0.9\,\hbox {V}$$ ± 0.9 V supply voltage.

Compact wide-stopband lowpass filter using stepped impedance hairpin resonator with radial stubs

Abstract: This study aims to define importance of use of low-pass filters in modern technologies, and then methods to design microstrip low-pass filters are examined. In following, an overview on related works in this context has been considered, and then a microstrip low-pass filter with a favorable function is designed that the way this filter is designed is as follow: 1- modify basic resonator and design a new resonator, 2design a low-pass filter with a proper function using designed resonator. Finally, the designed filter is made, that the response by the given sample properly adapts with the response by the sample undergone analysis. Further, to define the proposed structure in a better way, the results from designed filter are compared with the results of previous works.

Low-Voltage High-Linearity Wideband Current Differencing Transconductance Amplifier and Its Application on Current-Mode Active Filter

Abstract: A low-voltage high-linearity wideband current differencing transconductance amplifier (CDTA) is presented in this paper. The CDTA consists of a current differencing circuit and a cross-coupling transconductance circuit. The PSPICE simulations of the proposed CDTA show a good performance: -3dB frequency bandwidth is about 900 MHz, low power consumption is 2.48 mW, input current linear range is ±100 μA and low current-input resistance is less than 20 Ω, high current-output resistance is more than 3 MΩ. PSpice simulations for a current-mode universal filter and a proposed high-order filter are also conducted, and the results verify the validity of the proposed CDTA.

Coupled-line dual-band bandpass filter with compact structure and wide stopband

Abstract: A novel dual-band bandpass filter with a compact structure and a wide stopband is proposed. The total structure includes coupled-line stubs and coupled-line connected sections, leading to a compact circuit. This proposed filter can be implemented easily by using single-layer microstrip technology. The measured results of a prototype filter show that it can operate at both 1.32 and 2.67 GHz and up to the 8 GHz 15 dB stopband.

Loss-Tolerant Allpass-Based Filter Bank Design Suitable for Integrated Optics

Abstract: This paper presents a novel design algorithm for a filter bank structure that is suitable for photonic integrated circuits. The proposed design is entirely based on the principle of loss-exhibiting allpass filtering, which is a behavior naturally observed in a variety of microscale optical components. The setup and mathematical optimization of the system is explored in detail from a signal processing perspective, and an algorithm based on convex and nonlinear optimization techniques is subsequently presented. The algorithm methodologically utilizes the otherwise-undesirable effect of waveguide loss to derive an allpass-based filter bank structure that is amenable to photonic implementation. The proposed structure is ideal for applications in time-stretched analog-to-digital converters, WDM network channelizers, and general optical signal multiplexers.

Multi-band interference optimization

Abstract: RF communications circuitry, which includes a first RF filter structure and control circuitry, is disclosed. The first RF filter structure includes a pair of weakly coupled resonators and a first tunable RF filter. The control circuitry provides a first filter control signal. The first tunable RF filter receives and filters an upstream RF signal to provide a first filtered RF signal, such that a center frequency of the first tunable RF filter is based on the first filter control signal.