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Showing papers on "Voltage-controlled filter published in 2008"


Journal ArticleDOI
TL;DR: In this article, a three-phase four-wire power filter consisting of an active power filter (APF) and a Zig-Zag transformer was developed for zero-sequence utility voltage.
Abstract: Active power filters (APFs) have been developed to solve the problems of harmonic suppression and reactive power compensation simultaneously, In this paper, a three-phase four-wire power filter comprising a three-phase three-wire APF and a Zig-Zag transformer is developed. A hardware prototype is implemented and tested to verify the performance of the proposed power filter under various ideal and non-ideal power conditions. Experimental results show that this three-phase four-wire power filter has the desired performance under limited zero sequence utility voltage.

111 citations


Proceedings ArticleDOI
01 Nov 2008
TL;DR: In this article, the authors proposed a filter design guideline for single-phase grid-connected PV inverters by analyzing the instantaneous voltage applied on the filter inductor and calculated the switching ripple current through the filter induction.
Abstract: This paper proposes filter design guideline for single-phase grid-connected PV inverters By analyzing the instantaneous voltage applied on the filter inductor, the switching ripple current through the filter inductor is precisely calculated Therefore, filter inductance can be designed accurately which guaranties the switching ripple current under the target value Proposed filter design method is verified by experiment

80 citations


Journal ArticleDOI
TL;DR: In this article, a dual-band broadband bandpass filter was implemented with good compactness and low insertion loss, and a good agreement was obtained between the simulation and measurement results.
Abstract: Dual-band bandpass filters featuring compact size and flexible frequency choice are demonstrated using resonators based on slotted ground structures. Two resonators based on slotted ground structures form the basis of the filter design. The resonators allow the back-to-back and face-to-face embedding configuration, hence, greatly reduces the physical size of the filters. By changing the sizes of the two resonators independently, the lower and upper resonance frequencies can be adjusted to the desired values. A dual-band broadband bandpass filter was implemented with good compactness and low insertion loss. A good agreement is obtained between the simulation and measurement results.

66 citations


Journal ArticleDOI
TL;DR: The key feature of this technique is that a photonics microwave delay-line filter with arbitrary bandpass response can be realized with only positive taps via nonuniform tap spacing.
Abstract: A new technique to implement a photonic microwave delay-line filter based on nonuniform tap spacing with arbitrary bandpass response is proposed and experimentally demonstrated. Being different from a regular photonic microwave delay-line filter where the taps are uniformly spaced, the proposed filter in this paper has nonuniformly-spaced taps. The key feature of this technique is that a photonics microwave delay-line filter with arbitrary bandpass response can be realized with only positive taps via nonuniform tap spacing. The use of the proposed technique to implement a flat-top bandpass filter is experimentally demonstrated.

59 citations


Patent
20 Feb 2008
TL;DR: In this article, an amplifier with integrated filter (e.g., an LNA) is described, which includes a gain stage, a filter stage, and a buffer stage.
Abstract: An amplifier with integrated filter (e.g., an LNA) is described. In one design, the amplifier may include a gain stage, a filter stage, and a buffer stage. The gain stage may provide signal amplification for an input signal. The filter stage may provide filtering for the input signal. The buffer stage may buffer a filtered signal from the filter stage. The amplifier may further include a second filter stage and a second buffer stage. The second filter stage may provide additional filtering for the input signal. The second buffer stage may buffer a second filtered signal from the second filter stage. All of the stages may be stacked and coupled between a supply voltage and circuit ground. The filter stage(s) may implement an elliptical lowpass filter. Each filter stage may include an inductor and a capacitor coupled in parallel and forming a resonator tank to attenuate interfering signals.

58 citations


Journal ArticleDOI
TL;DR: A novel wide-tuning high-Q active bandpass filter utilizing the active inductors is presented, and issues of theactive inductor related to Q -enhancement, noise, linearity, and stability are considered.
Abstract: In this paper, design techniques for an integrated RF bandpass filter are discussed. A novel wide-tuning high-Q active bandpass filter utilizing the active inductors is presented. Issues of the active inductor related to Q -enhancement, noise, linearity, and stability are considered. The circuit has been fabricated in an 0.18-mum CMOS process, and the filter occupies the active area of 150 times 200 mum2. Measurement results show that the filter centered at 3.82 GHz with about 36-MHz bandwidth (3-dB) is tunable in frequency from about 1.92 to 3.82 GHz, and it exhibits -15- to 1-dB compression point at 2.44 GHz with approximately 60-MHz bandwidth while the dc power consumes 10.8 mW.

58 citations


Patent
12 Mar 2008
TL;DR: In this paper, the authors describe techniques for reducing adverse effects of TX signal leakage in a full-duplex, wireless communication device using a notch filter to reject TX signals in a signal processed in the RX path of the device.
Abstract: This disclosure describes techniques for reducing adverse effects of TX signal leakage in a full-duplex, wireless communication device. The techniques make use of a notch filter to reject TX signal leakage in a signal processed in the RX path of the wireless communication device. The notch filter may be constructed as a complex notch filter using passive resistor and capacitor components to produce a notch frequency that attenuates TX signal leakage components in a desired signal. The notch filter may be applied to a down-converted, baseband signal produced by a passive mixer.

50 citations


Journal ArticleDOI
TL;DR: A first-order all-pass filter with electronic tuning properties is presented that is cascadable, has small sensitivities, and suitable for monolithic integration, and can also operate at high frequencies.
Abstract: A first-order all-pass filter (APF) with electronic tuning properties is presented The filter consists of only active components and a single-grounded capacitor The circuit is cascadable, has small sensitivities, and suitable for monolithic integration, and it can also operate at high frequencies

50 citations


Proceedings ArticleDOI
15 Jun 2008
TL;DR: In this article, the authors presented the first suspended 3-pole RF MEMS tunable filter with a frequency coverage of 1.6-2.4 GHz, which is the best report at this frequency range using any planar technology.
Abstract: This paper presents the first suspended 3-pole RF MEMS tunable filter with a frequency coverage of 1.6-2.4 GHz. The suspended topology is chosen to result in a high-Q resonator, which is essential for a low-loss 3-pole filter. The filter results in an insertion loss of 1.34-3.03 dB over the tuning range and a 3-dB bandwidth of 201-279 MHz. This design results in a tunable Q u of 50-150 over the frequency range, which is to our knowledge, the best report at this frequency range using any planar technology.

46 citations



Journal ArticleDOI
TL;DR: In this paper, a high input impedance voltage-mode universal biquadratic filter with three input terminals and five output terminals is presented, which uses three plus-type differential difference current conveyors, two grounded resistors and two grounded capacitors.
Abstract: A new high input impedance voltage-mode universal biquadratic filter with three input terminals and five output terminals is presented The proposed circuit uses three plus-type differential difference current conveyors, two grounded resistors and two grounded capacitors The proposed circuit can realize all the standard filter functions: lowpass, bandpass, highpass, notch and allpass, without component matching conditions The proposed circuit offers the features of high input impedance, low active and passive sensitivities and the use of only grounded resistors and capacitors

Journal ArticleDOI
TL;DR: In this article, the authors proposed a new currentmode current-controlled single-input multiple-output type universal filter using non-inverting and inverting second generation current controlled conveyors (CCCII(±)s).
Abstract: This paper proposes a new current-mode current-controlled single-input multiple-output type universal filter using non-inverting and inverting second generation current-controlled conveyors (CCCII(±)s). The proposed circuit employs four CCCII(±)s and two grounded capacitors, and it can simultaneously realize lowpass, bandpass, highpass, bandstop and allpass filter outputs. The circuit offers an independent electronic control of the natural angular frequency (ω0) and quality factor (Q) by means of adjusting the bias current of the CCCII(±)s. The parameter sensitivities are all very low. Moreover, a high Q-value filter can be easily obtained by adjusting the ratio of two bias currents. PSPICE simulation results at the natural frequency of 1.27 MHz are given to demonstrate the advantages of the proposed circuit.

Journal ArticleDOI
TL;DR: In this article, three voltage-mode universal biquadratic filters with single input and five outputs have been proposed, which can simultaneously realize voltagemode lowpass (LP), bandpass (BP), highpass (HP), bandstop (BS) and allpass (AP) responses employing all grounded passive components.
Abstract: Three new voltage-mode universal biquadratic filters configuration are proposed. The first proposed high-input impedance universal filter with single input and five outputs, which can simultaneously realize voltage-mode lowpass (LP), bandpass (BP), highpass (HP), bandstop (BS) and allpass (AP) filter responses employing all grounded passive components. The second proposed high-input impedance universal filter with three input and single output, which also can realize all the standard filter functions without requiring any inverting input voltage signal. The third proposed universal filter with three inputs and five outputs, which can be used as either a three-input single-output or a two-input five-output universal filter. Moreover, each of the proposed circuits still enjoys (i) the employment of only grounded capacitors, and (ii) no requirement with the component choice conditions to realize specific filtering functions.

Journal ArticleDOI
TL;DR: A new cost-function for an optimization algorithm to achieve a multiple passband filtering function has been introduced and a high-temperature superconductor ten-pole filter with triple-band performance has been designed and fabricated to verify this algorithm.
Abstract: The increasing demand on microwave spectrum for communication systems has been the driving force in the filter industry. Multiple filtering characteristics have become necessary for many filter designs in mobile and satellite applications. In this paper, a new cost-function for an optimization algorithm to achieve a multiple passband filtering function has been introduced. A high-temperature superconductor ten-pole filter with triple-band performance has been designed and fabricated to verify this algorithm. Each of the three passbands has a fractional bandwidth of approximately 0.26%.

Journal ArticleDOI
TL;DR: In this paper, an improved hairpinline microstrip narrowband bandpass filter with via ground holes is presented, which reduces the size of the filter by 35% as compared to the conventional design.
Abstract: In this paper, we present a novel improved hairpinline microstrip narrowband bandpass filter with via ground holes. The new filter design methodology is derived from conventional hairpinline filter design. This design methodology incorporates use of λ/8 resonators, thereby reducing the size of the filter by 35% as compared to the conventional design. An analysis is presented to show the effects of tap point height and microstrip width on fundamental parameters of filter and subsequent relationships are developed. Through use of via ground holes and a wider microstrip line for resonators, 3 dB Fractional Bandwidth (FBW) less than 2%, Insertion Loss (IL) less than 1.6 dB and Return Loss (RL) better than 40 dB is achieved with midband center frequency 1 GHz. Spurious response suppression is achieved till 3f0. Robustness of this design approach is demonstrated by designing filters on two more substrates having er 2.17 and 9.2. As low as 0.48% FBW was achieved by using different substrates. The design approach is successfully tested for center frequency upto 2 GHz beyond which folding the resonator becomes practically difficult. Finally, a bandpass filter is designed with this design methodology and fabricated using FR4 substrate. S-parameter measurements show a good agreement with the simulated results.

Journal ArticleDOI
TL;DR: In this article, an analytic design procedure for microstrip tunable filters is described, where step-impedance resonators are employed and loaded with varactors for achieving agility in the filter response.
Abstract: This paper describes an analytic design procedure for microstrip tunable filters. Step-impedance resonators are employed and loaded with varactors for achieving agility in the filter response. Fixed lumped capacitors are utilized as admittance inverters in order to minimize the number of varactors in the filter. An analytic approach for filter design makes it possible to achieve a tunable filter showing the same frequency response when the center frequency is adjusted. A two-pole microstrip tunable filter whose center frequency can be adjusted from 1.1 to 1.5 GHz is designed to demonstrate the validity of design theory. A prototype tunable filter operating from 2.1 to 2.7 GHz is also designed and measured. A good agreement between the measured and simulated results is shown. Finally, three- and four-pole tunable filters are designed to show straightforward application of the presented design method to higher order tunable filter design.

Journal ArticleDOI
TL;DR: A compact reconfigurable 8-bit optical matching filter fabricated using 4% delta high-index-contrast silica-on-silicon waveguides is demonstrated and its working principle is demonstrated by successfully correlating 8- bit binary phase-shift-keyed patterns.
Abstract: We demonstrate a compact reconfigurable 8-bit optical matching filter fabricated using 4% delta high-index-contrast silica-on-silicon waveguides. This planar lightwave circuit is based on an eighth-order tap-and-delay finite impulse response architecture. Multimode interference-based splitters/combiners along with variable optical attenuators and phase shifters allow us to tune and dynamically reconfigure all the taps and delays (filter coefficients) in the filter using a simple automated algorithm. The filter is designed to recognize 8-bit patterns in 40-Gb/s data streams and we demonstrate its working principle by successfully correlating 8-bit binary phase-shift-keyed patterns.

Journal ArticleDOI
TL;DR: A general structure for realizing high-order current-mode analog filter responses with single-input and three-outputs is presented and does not require any component matching constraints thus it is suitable for fully integrated circuit (IC) technology.

Journal ArticleDOI
TL;DR: In this article, a compact elliptic function lowpass filter using a stepped impedance hairpin resonator is proposed, which has the advantages of compact size, low insertion loss, easy fabrication, a wide stopband, and sharp cutoff frequency response.
Abstract: A compact elliptic function lowpass filter using a stepped impedance hairpin resonator is proposed. The filter has the advantages of compact size, low insertion loss, easy fabrication, a wide stopband, and sharp cutoff frequency response. In order to cause a sharp cutoff frequency response and the wide stopband suppression, a coupled stepped impedance resonator is taken into consideration for the newly proposed lowpass filter. A demonstration filter has been designed, fabricated and tested, and the results agree well with the theory. The size of the filter is less than 0.037 lambdag times 0.093 lambdag, where lambdag is the waveguide length at the cutoff frequency 1.5 GHz, and the 10 dB rejection stopband can be extended to more than 15 GHz. The filter is useful for many microwave system applications.

Journal ArticleDOI
TL;DR: In this paper, a compact electronically switchable parallel-coupled microstrip bandpass filter (BPF) based on quarter-wavelength resonators and p-i-n diode switch is proposed.
Abstract: In this letter, a compact electronically switchable parallel-coupled microstrip bandpass filter (BPF) based on quarter- wavelength resonators and p-i-n diode switch is proposed. The proposed filter occupies only half the circuit size of the conventional parallel-coupled filter. In addition, the type and length of each coupled-line section is suitably chosen such that the inherent transmission zeros associated with the coupled-lines can be used to reject the spurious passbands effectively. By adding only one p-i-n diode along with a simple bias control circuitry, the proposed filter becomes electronically switchable with no current consumption when the filter is turned off. Specifically, a switchable fourth-order microstrip BPF with a center frequency f0 of 2 GHz, passband insertion loss less than 3 dB, and wide stopband up to 7.7 f0 in the ON state is demonstrated. The isolation of the filter is better than 30 dB from dc up to 7.7 f0 in the OFF state.

Journal ArticleDOI
TL;DR: In this article, a pre-design circuit is presented, which is composed of an inductive coupled line bandpass filter and an out-of-phase capacitive coupled-line band pass filter.
Abstract: This paper proposes a novel compact balanced-to-unbalanced bandpass filter. Firstly, a pre-design circuit is presented, which is composed of an inductive coupled-line bandpass filter and an out-of-phase capacitive coupled-line bandpass filter. A novel compact circuit with three coupled lines configuration, derived from the pre-design circuit, is then proposed for miniaturizing the balanced-to-unbalanced bandpass filter. A 2.4-GHz multilayer ceramic chip type balanced-to-unbalanced bandpass filter with a size of 2.0 mm times 1.2 mm times 0.7 mm is developed to validate the feasibility of the proposed structure. The filter is designed by using circuit simulation, as well as full-wave electromagnetic simulation softwares, and fabricated by the use of low-temperature co-fired ceramic technology. The measured results agree quite well with the simulated. According to the measurement results, the maximum insertion loss is 1.65 dB, the maximum in-band phase imbalance is within 3deg, and the maximum in-band magnitude imbalance is less than 0.32 dB.

Journal ArticleDOI
TL;DR: The voltage-mode biquad filter as mentioned in this paper employs one differential difference current conveyor (DDCC), two single-ended operational transconductance amplifiers (OTAs) and two grounded capacitors.
Abstract: The voltage-mode (VM) biquad filter is presented, which employs one differential difference current conveyor (DDCC), two single-ended operational transconductance amplifiers (OTAs) and two grounded capacitors. The proposed circuit can realize three kinds of filter response that is low-pass, high-pass and band-pass filters from the same configuration. The proposed circuit has no requirements for component-matching conditions and all of elements have no floating effects and any resistances. The proposed circuit has been confirmed by HSPICE simulations and compared with theoretical functions by MATLAB. Finally, to verify our architecture, we have designed this analog filter chip with TSMC 0.35 μ m 2P4M CMOS technology. This chip contains 129 transistors, operates to 2.18 MHz and consumes 83 mW. The chip area of the analog filter is 0.822 mm 2 .

Proceedings ArticleDOI
26 Sep 2008
TL;DR: In this article, a systematic filter design approach based on a specific filter attenuation requirement and volumetric component parameters is presented for an EMC input filter of a single-phase power converter for the power levels of 100 W, 300 W and 500 W.
Abstract: Input filters of power converters for compliance with regulatory electromagnetic compatibility (EMC) standards are often over-dimensioned in practice due to a non-optimal selection of number of filter stages and/or the lack of solid volumetric models of the inductor cores. This paper presents a systematic filter design approach based on a specific filter attenuation requirement and volumetric component parameters. It is shown that a minimal volume can be found for a certain optimal number of filter stages for both the differential mode (DM) and common mode (CM) filter. The considerations are carried out exemplarily for an EMC input filter of a single-phase power converter for the power levels of 100 W, 300 W, and 500 W.

Journal ArticleDOI
TL;DR: In this paper, a versatile voltage-mode universal biquad filter using two single-output-operational transconductance amplifiers (OTAs), one differential difference current conveyor (DDCC) and two capacitors is proposed.
Abstract: A novel electronically tunable versatile voltage-mode universal biquad filter by using two single-output-operational transconductance amplifiers (OTAs), one differential difference current conveyor (DDCC) and two capacitors is proposed. The proposed circuit, which can be used as either a four-input single-output universal filter or a single-input three-output multifunction filter with the same topology. Besides, the new circuit offers the following advantageous features: realization of all the non-inverting and inverting biquadratic filter signals from the same configuration, no need to employ inverting-type input signals, no need to component-matching conditions and low passive sensitivity performance.

Journal ArticleDOI
TL;DR: In this paper, a dual-band bandpass filter using microstrip open-loop resonators is presented, which can be used as unit element of duan-band filter design.
Abstract: This paper presents a novel dual-band banpass filter using microstrip open-loop resonators. A new microstrip unit of dual-band bandpass filter is introduced, which can be used as unit element of duan-band filter design. The two open-loop resonators are treated as passband resonator and stopband resonator in analysis, respectively. A five-pole C-band dual-band bandpsss filter has been designed and fabricated. The measured results show a good agreement with the simulated results.

Journal ArticleDOI
TL;DR: A novel bandpass filter design that incorporates automatic gain control (AGC) is proposed that reduces the performance requirements of a wide-band AGC, and allows for low-power multichannel compression.
Abstract: In this paper, we propose a novel bandpass filter design that incorporates automatic gain control (AGC). The gain control in the filter reduces the performance requirements of a wide-band AGC, and allows for low-power multichannel compression. The filter achieves up to 15 dB of compression on a 55-dB input dynamic range and is tunable over the audio frequency range, with microwatt power consumption and <5% harmonic distortion.

Patent
30 Dec 2008
TL;DR: In this article, a frequency compensation method for voltage-mode switching regulators is proposed, where a lowpass filter and a bandpass filter are employed in the two signal paths into the dual inputs of PWM comparators.
Abstract: A frequency compensation method for voltage-mode switching regulators is disclosed A lowpass filter and a bandpass filter are employed in the two signal paths into the dual inputs of PWM comparators In one embodiment, two zeros are generated to compensate for the L-C output filter poles Stable operation, low output voltage ripple and fast load transient response are achieved; while the power consumption of error amplifier and the area for implementing on-chip passive components are greatly reduced

Patent
08 Sep 2008
TL;DR: In this paper, a subtractor subtracts a first control signal output from a first bandpass filter from an error signal, and supplies a differential signal to a second band pass filter.
Abstract: A subtractor subtracts a first control signal output from a first bandpass filter from an error signal, and supplies a differential signal to a second bandpass filter. The second bandpass filter, which has a central frequency of 70 Hz, is affected by an operation of the first bandpass filter, i.e., a first control signal, which has a central frequency of 40 Hz. The first bandpass filter is not affected by an operation of the second bandpass filter, i.e., the second control signal.

Proceedings ArticleDOI
15 Jun 2008
TL;DR: In this paper, an active feedback filter for reducing the common mode (CM) electromagnetic interference (EMI) noise suitable for off-line power converters was proposed, where a simple feedback structure employing a high frequency linear amplifier and passive filter components has been designed.
Abstract: This paper presents a study on the design and implementation of an active filter for reducing the common mode (CM) electromagnetic interference (EMI) noise suitable for off-line power converters. A current-sense voltage-feedback topology has been selected from those reported in literature. The selected topology has the advantage that its high frequency active noise compensation circuit is isolated from the mains. A simple feedback structure employing a high frequency linear amplifier and passive filter components has been designed. The major problem with active feedback filter is the stability of the feedback system, which is influenced by the parasitics of the circuit components. Special attention has been paid to both stability analysis and practical implementation of the filter. A prototype of the active CM filter has been built and tested. The analysis and the experimental results demonstrate the usefulness and limitations of such an active CM EMI filter.

Journal ArticleDOI
TL;DR: In this article, a high-gain feedback control strategy is proposed, which is independent of circuit parameters, based on circuit analyses, such as selection of the dc-side voltage, regulation of the modulation index, system stability conditions, filter design, and switching noise.
Abstract: A shunt active dc filter (ADF) has been applied in high-voltage dc transmission systems for harmonic suppression. Some key problems in the design of ADF control systems have not been investigated thoroughly due to high harmonic frequency and the complexity of system modeling. In this paper, a high-gain feedback control strategy is proposed, which is independent of circuit parameters. The authors draw a comparison between the harmonic suppression effects of ADF and that of a passive filter and prove that the former can increase the series impedance of the hybrid filter, while the latter can decrease the equivalent voltage. Based on circuit analyses, solutions, such as selection of the dc-side voltage, regulation of the modulation index, system stability conditions, filter design, and switching noise are presented. The consistency between theory analyses and experimental results verifies the feasibility of the proposed control strategy.