Showing papers on "Band-stop filter published in 2006"

Band stop filter employing a capacitor and an inductor tank circuit to enhance MRI compatibility of active medical devices

Abstract: A band stop filter is provided for a lead wire of an active medical device (AMD). The band stop filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the lead wire of the AMD, wherein values of capacitance and inductance are selected such that the band stop filter is resonant at a selected frequency. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the band stop filter to attenuate current flow through the lead wire along a range of selected frequencies. In a preferred form, the band stop filter is integrated into a TIP and/or RING electrode for an active implantable medical device.

Dual-Band Microstrip Bandpass Filter Using Stepped-Impedance Resonators With New Coupling Schemes

Abstract: A microstrip bandpass filter using stepped-impedance resonators is designed in low-temperature co-fired ceramic technology for dual-band applications at 2.4 and 5.2 GHz. New coupling schemes are proposed to replace the normal counterparts. It is found that the new coupling scheme for the interstages can enhance the layout compactness of the bandpass filter; while the new coupling scheme at the input and output can improve the performance of the bandpass filter. To validate the design and analysis, a prototype of the bandpass filter was fabricated and measured. It is shown that the measured and simulated performances are in good agreement. The prototype of the bandpass filter achieved insertion loss of 1.25 and 1.87 dB, S11 of -29 and -40 dB, and bandwidth of 21% and 12.7% at 2.4 and 5.2 GHz, respectively. The bandpass filter is further studied for a single-package solution of dual-band radio transceivers. The bandpass filter is, therefore, integrated into a ceramic ball grid array package. The integration is analyzed with an emphasis on the connection of the bandpass filter to the antenna and to the transceiver die

Novel U-slot and V-slot DGSs for bandstop filter with improved Q factor

Abstract: Novel slot-shaped defected ground structures (DGSs) on the microstrip line are presented to provide a band-rejection property with an improved Q factor. Two different geometries (U-slot and V-slot) are investigated. U-slot and V-slot DGSs have simple shapes compared to the conventional DGSs, however, they provide more steep rejection characteristics. The Q factor of the band-rejection property for the U-slot DGS increases when the distance between two slots in the U-shape decreases. Similarly, the V-slot DGS provides a higher Q characteristic when the slot angle is reduced. Two bandstop filters are designed and fabricated employing three cascaded U-slot DGSs and V-slot DGSs, respectively. Experimental result shows that the high-Q band-rejection filter with three U-slot DGSs provides Q of 38.6. A fabricated filter with three cascaded V-slot DGSs also rejects the signals at the frequencies from 3.5 to 4.3 GHz with more than 20-dB suppression

Miniaturized microstrip lowpass filter with wide stopband using double equilateral U-shaped defected ground structure

Abstract: A compact double equilateral U-shaped defected ground structure (DGS) unit is proposed. In contrast to a single finite attenuation pole characteristic offered by the conventional dumbbell DGS, the proposed DGS unit provides dual finite attenuation poles that can be independently controlled by the DGS lengths. A 2.4-GHz microstrip lowpass filter using five cascaded double U-shaped DGS units is designed and compared with conventional DGS lowpass filters. This low pass filter achieves a wide stopband with overall 30-dB attenuation up-to10 GHz and more than 42% size diminution.

Dual-Mode Dual-Band Bandpass Filter Using Stacked-Loop Structure

Abstract: In this letter, a dual-mode dual-band bandpass filter using stacked-loop structure is proposed, which allows two transmission paths to radio frequency (RF) signals. Each of them using dual-mode resonators results in respective passband. This can provide convenience to easily change one passband frequency, while another keeps almost the same. Several attenuation poles in the stopband are realized to improve the selectivity of the proposed bandpass filter. The theoretical and measured results are presented and show good agreement

An Improved Adaptive Power Line Interference Canceller for Electrocardiography

Abstract: Power line interference may severely corrupt a biomedical recording. Notch filters and adaptive cancellers have been suggested to suppress this interference. We propose an improved adaptive canceller for the reduction of the fundamental power line interference component and harmonics in electrocardiogram (ECG) recordings. The method tracks the amplitude, phase, and frequency of all the interference components for power line frequency deviations up to about 4 Hz. A comparison is made between the performance of our method, former adaptive cancellers, and a narrow and a wide notch filter in suppressing the fundamental power line interference component. For this purpose a real ECG signal is corrupted by an artificial power line interference signal. The cleaned signal after applying all methods is compared with the original ECG signal. Our improved adaptive canceller shows a signal-to-power-line-interference ratio for the fundamental component up to 30 dB higher than that produced by the other methods. Moreover, our method is also effective for the suppression of the harmonics of the power line interference

A Micropower Chopper-Stabilized Operational Amplifier Using a SC Notch Filter With Synchronous Integration Inside the Continuous-Time Signal Path

Abstract: A micropower chopper stabilized opamp is presented. The new topology incorporates a switched capacitor filter with synchronous integration inside the continuous time signal path virtually eliminating chopping noise. A three-stage amplifier with multipath nested Miller compensation is modified to incorporate chopping of the input stage, sinc filtering to notch any chopping ripple, and a compensation scheme to maintain an undistorted high-speed signal path. Characteristics of the amplifier presented include rail to rail input and output operating on supplies of 1.8 to 5.5 V over -40degC to 125degC. Quiescent supply current is 17 muA, input offset is 3 muV, input offset drift is 0.02 muV/degC, GBW is 350 kHz, and the chopping frequency is 125 kHz. Die area is 0.7 mm2 using a precision analog mixed-signal CMOS process combining low-noise 0.6-mum analog transistors with 0.3-mum digital CMOS capability

A Micropower Chopper-Stabilized Operational Amplifier using a SC Notch Filter with Synchronous Integration inside the ContinuousTime Signal Path

Abstract: A micropower chopper-stabilized opamp uses an SC notch filter with synchronous integration inside the CT signal path to eliminate chopping noise. Characteristics include rail-to-rail I/O, 15muA supply current at 1.8 to 5.5V, 2muV offset, 55nV/radicHz noise, 350kHz GBW, and a chopping frequency of 125kHz. The die area is 0.7mm2 using 0.6mum CMOS

Space-mapping optimization of planar coupled-resonator microwave filters

Abstract: This paper presents an iterative technique for the design of planar coupled-resonator microwave filters, which exploits initial information on the equivalent circuit elements within the space-mapping technique. To accelerate the convergence of the design process, information on the dependence of the elements of the equivalent circuit on adjustable geometrical and physical parameters, which is available from the initial design step, is used. The technique is applied to design harmonic-reject planar filters. Results from applications to fourth- and sixth-order filters show that the successful designs are achieved with at most two iterations. A sixth-order harmonic-reject filter is then fabricated and measured.

A novel cross-shape DGS applied to design ultra-wide stopband low-pass filters

Abstract: This letter presents a novel low-pass filter with an ultra-wide stopband. The proposed filter is comprised of a new cross-shape defected ground structure (CSDGS). By using this structure, the filter not only supports conventional DGS performances with a sharp rejection, but also exhibits an ultra-wide stopband. For the deigned low-pass filter, an insertion loss of less than 2dB from dc to 3.5GHz and the rejection is better than 20dB from 4.3 to 15.8GHz. Predicted performances show widened and deepened stopband beyond the low passband. Furthermore, it is confirmed by measurement.

A novel three-phase magnitude-phase-locked loop system

Abstract: A novel three-phase magnitude-phase-locked-loop system (3MPLL) for use in the general area of three-phase (power, energy and power electronic) systems is introduced. The proposed 3MPLL suppresses the noise and distortion from the input signal, mitigates the unbalance, and synthesizes the instantaneous positive-sequence component of the input signal; thus it operates as a nonlinear adaptive notch (or band-pass) filter. The 3MPLL also adaptively tracks and estimates the magnitude, phase angle, and frequency of the input signal; thus, its operation as a nonlinear state estimator. Characteristics of the 3MPLL including its mathematical equations as well as steady-state and dynamic responses are discussed in this paper. Comparisons are made between the proposed 3MPLL and conventional single-phase PLL (1PLL) and three-phase PLL (3PLL) systems. Advantages of the proposed system over the conventional methods and systems are also discussed. Structural simplicity and robustness of the 3MPLL system are its further features which make it desirable. In addition to the conventional applications of the 3PLL in the general area of power systems, the proposed 3MPLL can also be used for other applications which require smooth and adaptive synthesis of the instantaneous symmetrical components. Particularly, the 3MPLL can be used as a three-phase nonlinear anti-aliasing filter with no phase-shift and no amplitude bias. Three unique features of such a filter are frequency adaptivity, unbalance mitigation, and structural simplicity/robustness

A New Method for Removal of Baseline Wander and Power Line Interference in ECG Signals

Abstract: Removal of baseline wander and power line interference in ECG signal is a classical problem. A new method is proposed to remove baseline wander and power line interference in ECG signal based on Empirical Mode Decomposition and notch filter. Principles and characteristics of Empirical Mode Decomposition are presented; ECG signal is decomposed into a series of Intrinsic Mode Functions (IMFs). Then 50Hz notch filter is designed, by which the IMF of ECG signal containing 50Hz power line inference is filtered. The "clean" ECG signal is reconstructed by properly selecting IMFs. To evaluate the performance of the filter, Clinic ECG signals are used. Results indicate that the baseline wander and power line interference of ECG are removed effectively by this new method.

A Single-Phase DG Generation Unit with Shunt Active Power Filter Capability by Adaptive Neural Filtering

Abstract: This paper deals with a single-phase Distributed Generation (DG) system with Active Power Filtering (APF) capability, devised for utility current harmonic compensation. The idea is to integrate the DG unit functions with the shunt APF capabilities, since the DG is connected in parallel to the grid. With the proposed approach, the control of the DG unit is performed by injecting into the grid a current with the same phase and frequency of the grid voltage and with amplitude depending on the power available from the renewable sources. On the other hand, the load harmonic current compensation is performed by injecting into the AC system harmonic currents as those of the load but with opposite phase, thus keeping the line current almost sinusoidal. Both the phase detection of the grid voltage and the computation of the load harmonic compensation current have been performed by two neural adaptive filters with the same structure, one in configuration "notch" and the other complementary in configuration "band". The methodology has been tested succesfully both in numerical simulation and experimentally on a suitably devised test setup.

Dual-Band Bandpass and Bandstop Filters Using Composite Right/Left-Handed Metamaterial Transmission Lines

Abstract: In this paper, dual-band bandpass and bandstop filters using composite right/left-handed (CRLH) metamaterial transmission lines (TLs) are developed. The conventional bandpass and bandstop filters are first designed using quarter-wave short-circuited and open-circuited stubs, respectively. Then the dual-band filters with arbitrary dual operating bands can then be easily implemented by replacing the microstrip lines with the CRLH TLs. The dual-band bandpass and bandstop filters using the CRLH TLs are experimentally demonstrated at dual operating frequencies 1 GHz and 1.9 GHz. The measured results are in a good agreement with the simulated results. From the measured performances, the dual-band bandpass filter has 29.8% and 17.3% pass bandwidths, while the dual-band bandstop filter has 12.2% and 6.9% stop bandwidths with 30dB attenuation

UWB Bandpass Filters with Multi Notched Bands

Abstract: This paper presented ultra-wideband (UWB) bandpass filters with single or multi notched band(s) for the purpose of "DAA: Detect and Avoid", to avoid the interference between the UWB radio system and the existing radio system. The filter is based on a novel UWB bandpass filter which consists a broadside-coupled microstrip-coplanar waveguide structure and exhibited its excellent ultra-wideband property, proposed by authors recently. The single and multi notched bands operation was implemented by integrating stub(s) in the broadside-coupled conductors. The resonance of each stub introduces a narrow rejection band in the UWB passband which then results in a single or multi notched band(s). Such UWB bandpass filter with notched band is useful and required in practical systems in order to avoid the interference between the UWB radio system and existing radio systems. The notched band can be easily designed to some specific frequency band(s) by tuning the length of the stub(s). Simulation, design, fabrication and measurement of the UWB bandpass filters with notched bands have been carried out mainly following FCC's spectrum mask. The proposed filters demonstrated both excellent ultra-wide bandwidth (from 2.8 GHz to 10.2 GHz) and rejection performance (> 50 dB at central frequencies for a single notched band, or 21 dB and 27 dB for triple bands), as well as good out-band performance better than the requirement of FCC's mask.

Narrowband interference suppression in time-hopping impulse radio ultra-wideband communications

Abstract: Ultra-wideband (UWB) technology has been considered an innovative solution for future short-range high-speed wireless communications. Interference suppression is important for the UWB devices to operate over spectrum occupied by narrowband systems. In this paper, the use of a notch filter in time-hopping impulse radio (TH-IR) for UWB communication is considered, where a Gaussian monopulse is employed with pulse position modulation. Lognormal channel fading is assumed, and a complete analytical framework is provided for the performance evaluation of using a transversal-type notch filter to reject narrowband interference (NBI). A closed-form expression of bit-error probability is derived, and the numerical results show that the use of a notch filter can improve the system performance significantly. Furthermore, a performance comparison between TH-IR and multicarrier code-division multiple-access (MC-CDMA) UWB systems is made under the conditions of the same transmit power, the same data rate, and the same bandwidth. It is shown that in the presence of NBI, the TH-IR system and MC-CDMA system achieve similar performance when both use a notch filter

2 GHz $rm Q$ -Enhanced Active Filter With Low Passband Distortion and High Dynamic Range

Abstract: A tunable Q-enhanced filter with low passband distortion is presented. The Q of the on-chip spiral inductors that form the filter resonators is enhanced by using a cross-coupled differential pair which is degenerated by a second LC tank. This technique allows for frequency dependent compensation of inductor losses and ensures that the Q-enhanced LC resonators have a frequency behaviour close to the ideal in the passband of the filter. The circuit allows DC voltage control of Q-enhancement. The filter centered at 2.0 GHz with a 130 MHz bandwidth is tunable in frequency by 3%, exhibits a -6.6 dBm 1-dB compression point and a 15 dB noise figure while consuming 17 mW of DC power. The circuit was fabricated in 0.18-mum CMOS and the performance was verified experimentally

Ultra-Wideband (UWB) Filter With WLAN Notch

Abstract: Strong narrowband signals like WLAN links may severely disturb UWB communication or sensor systems. In some cases, filtering out the respective frequency bands may therefore be of interest. This contribution proposes an additional notch filter within the passband of a broadband filter normally used to tailor the UWB spectrum. To this extent, a resonant slot is incorporated into one of the elements of a suspended stripline filter. Simulated and experimental results of a filter of this kind are presented, demonstrating the feasibility of this approach.

A BiCMOS Ultra-Wideband 3.1–10.6-GHz Front-End

Abstract: This paper presents a direct-conversion receiver for FCC-compliant ultra-wideband (UWB) Gaussian-shaped pulses that are transmitted in one of fourteen 500-MHz-wide channels within the 3.1-10.6-GHz band. The receiver is fabricated in 0.18-mum SiGe BiCMOS. The packaged chip consists of an unmatched wideband low-noise amplifier (LNA), filter, phase-splitter, 5-GHz ISM band switchable notch filter, 3.1-10.6-GHz local oscillator (LO) amplifiers, mixers, and baseband channel-select filters/buffers. The required quadrature single-ended LO signals are generated externally. The average conversion gain and input P1dB are 32 dB and -41 dBm, respectively. The unmatched LNA provides a system noise figure of 3.3 to 5 dB over the entire band. The chip draws 30 mA from 1.8 V. To verify the unmatched LNA's performance in a complete system, wireless testing of the front-end embedded in a full receiver at 100 Mbps reveals a 10-3 bit-error rate (BER) at -80 dBm sensitivity. The notch filter suppresses out-of-band interferers and reduces the effects of intermodulation products that appear in the baseband. BER improvements of an order of magnitude and greater are demonstrated with the filter

Ultra-wideband bandpass filter using CPW-to-microstrip coupling structure

Abstract: A novel ultra-wideband bandpass filter based on a back-to-back microstrip-CPW transition structure is presented. The filter is composed of two microstrip-CPW transitions and a section of microstrip line used as a multiple-mode resonator. The filter has been investigated numerically and experimentally. Both simulated and measured results show that the filter has a good performance, including a small insertion loss, a group delay variation of less than 0.2 ns, stopband of up to 16.0 GHz at high frequencies, and an out-of-band rejection level of below -20.0 dB.

Novel compact microstrip square ring bandpass filters

Abstract: Three types of novel microstrip bandpass filters, a square split ring stepped-impedance bandpass filter, a square ring stepped-impedance bandpass filter, and a dual-mode square ring bandpass filter, which operate from L to S waveband are proposed, their filter performances are calculated. In these novel structures, ring stepped-impedance resonator, DGS and dual-mode technique are applied to not only reduce the volume but also improve the frequency responses of filters. The optimized results show that microstrip bandpass filter with DGS has nicer performances such as low insertion losses, wide stopband responses etc., while with dual-mode technique, a pair of transmission zeros can be implemented and the filter performances are effectively improved. The filters proposed in this paper have outstanding advantages such as compact and novel structures, small volumes, high selectivity, wide stopband responses, low insertion losses and so on, and can be applied in wearable systems.

Application of optical broadband monitoring to quasi-rugate filters by ion-beam sputtering

Abstract: Methods for the manufacture of rugate filters by the ion-beam-sputtering process are presented. The first approach gives an example of a digitized version of a continuous-layer notch filter. This method allows the comparison of the basic theory of interference coatings containing thin layers with practical results. For the other methods, a movable zone target is employed to fabricate graded and gradual rugate filters. The examples demonstrate the potential of broadband optical monitoring in conjunction with the ion-beam-sputtering process. First-characterization results indicate that these types of filter may exhibit higher laser-induced damage-threshold values than those of classical filters.

Multiline two-dimensional guided-mode resonant filters

Abstract: A novel multiline filter using a two-dimensional guided-mode resonant (GMR) filter is proposed. The filter concept utilizes the multiple planes of diffraction produced by the two-dimensional grating. Multiple resonances are obtained by matching the guided modes in the different planes of diffraction to different wavelengths. It is shown that the location and the separation between resonances can be specifically controlled by modifying the periodicity of the grating and the other physical dimensions of the structure. This is in contrast to the one-dimensional GMR filters where the location of the resonances is material dependent. Two-line reflection filter designs with spectral linewidths less than 1 nm and a controllable spectral separation of up to 23% of the short resonance wavelength are presented using rectangular-grid grating GMR structures. Three-line filters are designed in hexagonal-grid grating GMR structures with two independently controllable resonance locations.

Design of multiple-stopband filters for interference suppression in UWB applications

Abstract: A design of multiple-stopband filters is presented for the suppression of interfering signals in UWB applications. Since possible interferers can be located at fixed frequencies or within a defined frequency band, the design of both fixed and tunable narrow stopband filter sections is addressed. For multiple fixed stopband filters, bent resonators, coupled to the main line, are introduced in order to more effectively suppress harmonics. A new tunable tapped stopband section is proposed, which allows the simultaneous control of stopband frequency and bandwidth. The final multiple-stopband design combines fixed and tunable sections and simultaneously suppresses interferences from global system for mobile communication, wireless local area network, worldwide interoperability for microwave access, and industrial-scientific-medical applications. Measurements verify the design process

High-selectivity dual-band stepped-impedance bandpass filter

Abstract: A highly selective dual-band stepped impedance bandpass filter is presented. The filter has two tunable passbands. Two finite out-of-band transmission zeros are realised, which have high selectivity.

Extended-stopband bandpass filter using both half- and quarter-wavelength resonators

Abstract: A novel quasielliptic microstrip bandpass filter (BPF) using both half- and quarter-wavelength resonators is proposed. With the quarter-wavelength (lambda/4) resonators placed in the interstage, the filter spurious passband can be pushed up to 3 f0 where f0 stands for the passband center frequency. To improve the stopband characteristics, a modified stopband-extended filter is implemented, utilizing the multiple transmission zeros placed at specified frequencies to achieve good frequency selectivity and out-of-band rejection. The modified filter provides a 22.5-dB rejection level from 1.14 f0 to 5.2 f0

Adaptive resonant mode compensation for hard disk drives

Abstract: This paper is concerned with a mechanical resonant mode compensation problem for hard disk drives. Conventional notch filters must have deep and wide enough frequency characteristics in order to accommodate all possible resonant mode characteristic perturbations, which result in deterioration in positioning accuracy and residual vibration after seeking. This paper proposes an easy-to-implement adaptive notch filter of which the center frequency follows the resonant frequency change. The basic idea of this adaptive filter is to balance two kinds of frequency weighted variances of the control input signal.

A high-performance ultra-narrow bandpass HTS filter and its application in a wind-profiler radar system

Abstract: This paper reports a recent development of a narrowband high-temperature superconducting (HTS) bandpass filter with a fractional bandwidth of 0.35% in the L band. The filter exhibits a 10-pole quasi-elliptic function response implemented with a cascaded quadruplet coupling structure. The measured filter shows a midband insertion loss of 0.26 dB and a return loss better than −15 dB over the passband. Steep rejection slopes are obtained at the band edges and the measured skirt slope has exceeded 120 dB MHz−1, resulting in an excellent out-of-band rejection very close to the band-edge. Combining this filter together with a special designed low-noise amplifier (LNA) as well as a cryo-cooler, an HTS subsystem was then constructed and mounted in the front end of a wind-profiler radar system, substituting the corresponding conventional parts. A field trial has shown that the HTS filter could markedly improve the sensitivity as well as the anti-interference capability of a wind-profiler radar system.