Low-pass Fllter Research Articles

Affection Recognition by GSR Signal Use a Improved K-nearest Neighbor Algorithm

For afiection recognition problems of GSR (Galvanic Skin Response) signal, this paper presents a method of afiection recognition based on a improved K-nearest neighbor algorithm. In this research, on the flrst step, the group collected 175 participants’ GSR signals on the test of emotional arousal which was acquired in the lab environment; then used the Batterworth low pass fllter to remove GSR signals noise, and extracted the original features of GSR signals at the same time; then recognized the flve feelings of happiness, sadness, fear, anger and calm with the improved K- nearest neighbor classifler. The experimental results show that the method can improves the accuracy of identiflcation indeed.

COMPACT LPF WITH SHARP ROLL OFF AND WIDE STOPBAND USING COUPLING STEPPED IMPEDANCE TRIANGULAR RESONATOR

A lowpass fllter with sharp transition and wide stopband using a novel coupling stepped- impedance triangular resonator is presented. The L-C equivalent circuit is developed for designing this type fllter and analyzing the mechanism for improving roll-ofi and rejection property. The stopband width, passband edge, roll-ofi rate and overall suppression level are afiected by coupling capacitance. The efiect of coupling capacitance is analyzed using calculated frequency response. Coupling triangular stubs provide adequate coupling capacitance resulting in balance among transition property, stopband width and suppression level easily. A single LPF unit is designed and fabricated with cutofi frequency of 860MHz. The single LPF unit exhibits 40-dB suppression level from 1.11GHz to 2.28GHz. A cascaded LPF with three asymmetric units provides 40-dB suppression level from 1.1GHz to 6.76GHz, and roll- ofi rate of 154dB/GHz with compact size as small as 0:23‚g £ 0:05‚g, where ‚g is guided wavelength at cutofi frequency.

DUAL-BAND FILTER FOR WIMAX AND WLAN WITH IMPROVED UPPER STOP BAND PERFORMANCE

In this paper, a novel and compact dual-band fllter with enhanced upper stop characteristics has been presented. Dual band pass fllter characteristics are achieved by introducing transmission zero (TZ) in pass band of band pass fllter (BPF). The wide band pass fllter (BPF) is implemented by combining low pass fllter characteristics (i.e., stepped impedance resonator) and high pass fllter characteristics (i.e., short stubs). Closed rectangular ring resonator (CRRR) and open loop rectangular ring (OLRR) combination is used to produce two transmission zeros (TZs). One TZ is placed on the pass band of BPF such that resultant fllter characteristic consists of two pass band. However, the second TZ is placed at edge of the pass band in BPF to improve skirt selectivity. The two pass bands are designed to cover two popular wireless bands namely WiMAX (center frequency f1 (3.5GHz) and WLAN (center frequency f2 (5.7GHz)) bands, i.e., 3.35{3.65GHz and 5.5{5.85GHz respectively. Equi-ripple low pass stepped impedance resonator (SIR) fllter response is responsible for improved and spurious free upper stop band (> 20GHz, i.e., > 6f1) and also provides sharp skirt attenuation at upper stop band. The proposed fllter is implemented on an RT/Duroid 5880 (r = 2:2) substrate with thickness of 0.785mm and surface area of 19 £ 12sq ¢ mm. Good agreement between simulated and measured results ensures that the proposed fllter is a suitable candidate for modern dual band communications.

UWB BANDPASS FILTER WITH HYBRID STRUCTURE AND TWO TRANSMISSION ZEROS IN THE NOTCHED BAND

An ultra-wideband (UWB) bandpass fllter (BPF) with hybrid coplanar waveguide (CPW)/microstrip structure is introduced in this paper. Then a pair of lowpass fllters is integrated on the CPW feed lines to achieve a good out-of-band rejection. At last, a notched band with two transmission zeros is realized at 5.8GHz by using a symmetric E-shaped slot-line and etching slots on microstrip resonator. Two transmission zeros are realized in the desired notched band, and out-of band rejection is more than 32dB. In order to prove the validity, the proposed fllter is fabricated and measured, and the measured results are in good agreement with simulated ones.

COMPACT WIDE STOPBAND QUASI-ELLIPTIC FUNCTION LOWPASS FILTER USING QUASI-LUMPED ELEMENTS

This paper presents a novel quasi-elliptic function lowpass fllter (LPF) by using quasi-lumped elements. The proposed LPF is flrstly based on a seven-order Chebyshev response lowpass prototype. Then, a series branches of shunt resonant LC circuit is introduced in the fllter design to provide a transmission zero close to the transition band, which can improve the roll-ofi rate of proposed LPF signiflcantly. To implement the lumped elements of lowpass prototype, the high- impedance meander lines are employed to realized the inductors while inter-digital microstrip lines and the microstrip parallel-plate structures are used to realize the capacitors. To validate the proposed method, a LPF with 3dB cutofi frequency fc at 1.9GHz is designed and fabricated. The measured results show that the fabricated LPF has a sharp roll-ofi rate up to i142dB/octave and i15dB harmonic suppression from 1:1fc to 9:7fc. Moreover, the fabricated LPF also has a compact size of 0:1‚gc £ 0:11‚gc. Good agreement can observed between the simulation and measurement.

DUAL-BAND DIFFERENTIAL FILTER USING BROADBAND COMMON-MODE REJECTION ARTIFICIAL TRANSMISSION LINE

A new balanced dual-band bandpass fllter with strong common-mode rejection is presented in this paper. Common-mode rejection is provided by a section of a periodic microstrip difierential line that behaves as a low-pass fllter under common-mode operation. In contrast, the difierential line exhibits very good all-pass behavior under difierential mode operation. This structure is combined with a difierential dual-band bandpass fllter based on embedded resonators. Simulations and experiments conflrm that the combined structure has good common-mode rejection within the passbands of the dual-band difierential fllter.

APPLICATION OF BILAYER ANISOTROPIC STRUCTURES FOR DESIGNING LOW-PASS FILTERS AND POLARIZERS

Arrangements of bilayer anisotropic structures are in- spected in this paper that manifest wonderful behaviors. One of these arrangements can pass TM & TE modes spontaneously in low frequen- cies and re∞ect them in higher frequencies and function as a low-pass fllter. Another arrangement can re∞ect TE mode and pass TM mode in a particular frequency band and vice versa and function as a polarizer. All the analyses are based on the calculations of the hybrid matrix of layers by means of a recursive algorithm. Also the efiect of the & tensors on the speciflcations of the fllters is discussed.

EFFECTIVE RECONSTRUCTION OF THE ROTATION-INDUCED MICRO-DOPPLER FROM A NOISE-CORRUPTED SIGNATURE

This paper presents an efiective method for reconstructing the rotation-induced micro-Doppler from a signature corrupted by noise. Based on empirical mode decomposition (EMD), a low-pass fllter is employed as its preprocessor in order to efiectively extract the flrst chopping harmonic component of the rotation-induced micro- Doppler. Then the extracted component is used for reconstructing the original micro-Doppler signature in the joint time-frequency domain. Although it is di-cult to interpret the time-frequency representation of the noise-corrupted signature, the reconstruction of the micro- Doppler enables the acquisition of related information and can be used for complementing other traditional analysis methods. By validating the applicability of the proposed method with measured jet engine modulation (JEM) signatures, we demonstrate that the reconstruction process presented in this paper is expected to be signiflcantly helpful for radar target recongnition in real environments.

A DUAL-BAND RF ENERGY HARVESTING USING FREQUENCY LIMITED DUAL-BAND IMPEDANCE MATCHING

In this paper, a novel dual-band RF-harvesting RF-DC converter with a frequency limited impedance matching network (M/N) is proposed. The proposed RF-DC converter consists of a dual-band impedance matching network, a rectifler circuit with villard structure, a wideband harmonic suppression low-pass fllter (LPF), and a termination load. The proposed dual-band M/N can match two receiving band signals and suppress the out-of-band signals efiectively, so the back-scattered nonlinear frequency components from the nonlinear rectifying diodes to the antenna can be blocked. The fabricated circuit provides the maximum RF-DC conversion e-ciency of 73.76% and output voltage 7.09V at 881MHz and 69.05% with 6.86V at 2.4GHz with an individual input signal power of 22dBm. Moreover, the conversion e-ciency of 77.13% and output voltage of 7.25V are obtained when two RF waves with input dual-band signal power of 22dBm are fed simultaneously.

COMPACT LOWPASS FILTER WITH WIDE STOPBAND USING NOVEL DOUBLE-FOLDED SCMRC STRUCTURE WITH PARALLEL OPEN-ENDED STUB

Nowadays, there is expanding interest in planar compact microstrip fllters applied to microwave wireless system. The compact microstrip resonant cell (CMRC) and spiral compact microstrip resonant cell (SCMRC) are more and more popular in fllter design due to their slow-wave and band-stop efiects. In this paper, a novel double-folded SCMRC (DSCMRC) is proposed, analyzed and measured, which turns out to have more compact dimensions and distinctly broader stopband than CMRC and SCMRC. Furthermore, an improved DSCMRC circuit with two parallel open-ended stubs that are added into the DSCMRC structure is presented, which could introduce more transmission zeros in the stopband for better out- of-band rejection than the original DSCMRC. The measured results show the excellent performance of the improved DSCMRC circuit structure. Finally, a novel low-pass fllter incorporating two improved DSCMRC in series is simulated and measured, which proves to have an excellent performance of out-of-band rejection up to 25GHz with a really compact circuit size.

MINIATURIZED UWB BANDPASS FILTER WITH DUAL NOTCH BANDS AND WIDE UPPER STOPBAND

In this paper, a miniature ultrawideband (UWB) bandpass fllter with dual notch bands and wide upper stopband is presented. The ultrawide passband characteristic is achieved using a microstrip to slot line transition, and a wide upper stop band is realized using an elliptical lowpass fllter. The dual band notches at 5.46GHz and 8.04GHz are obtained by incorporating defected microstrip structure in the input and output sections. A prototype of the proposed UWB bandpass fllter is fabricated and measured. The equivalent circuit of the proposed fllter is also presented. A good agreement between the measured, EM simulated and circuit simulated responses is obtained.

DESIGN OF COMPACT LOWPASS FILTER WITH ULTRA-WIDE STOPBAND USING THIN SLOTS

This paper presents a compact microstrip stepped- impedance lowpass fllter with ultra-wide stopband by using back-to- back C-shaped and triple C-shaped thin slots. The properties of several thin slots in the ground plane have been investigated in this paper. With the full-wave simulation results and a simplifled equivalent model, the total equivalent inductance of the thin slots can be extracted at cutofi frequency for lowpass fllter design purpose. On the other hand, the thin slots work as bandstop fllter at the stopband of the lowpass fllter for a better stopband rejection. The proposed lowpass fllter with a cutofi frequency of 2GHz shows a wide stopband with an over 25-dB attenuation up to 17.5GHz. From dc to 2GHz, the insertion loss is less than 0.3dB and the return loss is greater than 20dB. In comparison to the conventional stepped-impedance lowpass fllter with the same passband performance, the proposed lowpass fllter shows not only a 24.3% size reduction but also a better stopband rejection.

RADIAL LOADED TRANSFORMED RADIAL STUB FOR LPF STOPBAND EXTENSION

A low pass fllter with ultra-wide band rejection and compact size using a proposed radial loaded transformed radial stubs is introduced and investigated. The implemented unite cell low pass fllter with 1-dB cutofi frequency fc of 3.2GHz demonstrates stopband rejection up to 11.8 fc, i.e., 38GHz. The design is further extended to the high-order LPF through cell cascading. The implemented four-cell LPF with fc of 3.6GHz demonstrated 35dB rejection from 4.8GHz to 39GHz, 50dB rejection from 5.4GHz to 26GHz (7.2 fc) and 20dB rejection from 4.4GHz to 50GHz (13.8 fc). The measured passband insertion loss is less than 1.7dB, and group delay is 0:45 » 0:8nS. The size of the four-cell low pass fllter is only 0:33‚g £ 0:135‚g, (‚g is the guide wavelength at center cutofi frequency) without using any lumped elements.

COMPACT LOWPASS FILTER WITH HIGH SELECTIVITY USING G-SHAPED DEFECTED MICROSTRIP STRUCTURE

In this paper, a novel G-shaped defected microstrip structure (DMS) is presented. Compared with the conventional DMS, the proposed G-shaped DMS exhibits lower resonant frequency and wider stopband. A lowpass fllter with 3dB cutofi frequency at 3.17GHz using four pairs of parallel cascaded G-shaped DMS units is designed and fabricated. The measured results show that the transition band is only 0.09GHz and the stopband over 25dB attenuation covers 3.4GHz to 10GHz. The measured and simulated results are in good agreement.

COMPACT MICROSTRIP LOWPASS FILTER WITH SHARP ROLL-OFF AND WIDE STOPBAND USING SEMICIRCLE ENDED STUB RESONATOR

In this paper, a semicircle ended stub resonator, cascaded to a modifled radial patch to design a compact lowpass fllter with sharp roll-ofi and wide stopband is proposed. This fllter has 3dB cutofi frequency at 1.54GHz. The transition band is only 0.26GHz from 1.54GHz to 1.8GHz with corresponding attenuation levels of i3dB and i20dB respectively. Maximum insertion loss is 0.1dB in the passband, and the stopband bandwidth with the attenuation level better than i20dB is extended from 1.8GHz up to 13.93GHz. So, a wide stopband is achieved. The proposed fllter is designed, fabricated and measured, where there is a good agreement between the simulation and measurement results. The results show that a roll-ofi rate of 65.4dB/GHz together with a relative stopband bandwidth of 154% with the suppression level of i20dB is obtained while achieving a high flgure of merit (FOM) of 23509.

A MINIATURIZED LOWPASS/BANDPASS FILTER USING DOUBLE ARROW HEAD DEFECTED GROUND STRUCTURE WITH CENTERED ETCHED ELLIPSE

A new double arrow head defected ground structure (DGS) with centered etched ellipse is proposed for designing a multilayer low pass fllter (LPF) with wide rejection band and low insertion loss in the stop-band. The prototype LPF consists of three double arrow head DGS with centered etched ellipse in the ground plane and compensated capacitor on the top layer of a 30 £ 40mm 2 Roger RT/Duroid5880 substrate having relative permittivity (r) of 2.2 and thickness of 0.78mm. The cutofi frequency is equal to 1.07GHz. The prototype LPF is then realized as multilayer structure to enhance the fllter response and reduce its size. The size reduction of the proposed multi-layer LPF is about 26% more than the conventional one. The proposed fllter has been fabricated and measured. Good agreement is achieved between the simulated and measured results. The fllter presents the advantages of compact size; low insertion loss and high out-band suppression. Finally, the multilayer LPF is transformed to band pass fllter (BPF) using J-inverter method.

A NEW WIDE-STOPBAND LOW-PASS FILTER WITH GENERALIZED COUPLED-LINE CIRCUIT AND ANALYTICAL THEORY

A generalized coupled-line circuit is introduced to construct a wide-stopband low-pass fllter in this paper. This circuit conflguration includes two-section coupled lines and a connected transmission-line stub. Due to the symmetry of this proposed structure, closed-form equations for scattering parameters are investigated. The transmission zeros and poles locations for difierent circuit parameters are discussed, and the corresponding design curves are given. For theoretical veriflcations, four typical numerical examples are designed, calculated and illustrated. Furthermore, two single-stage low-pass fllters (LPF 1 and LPF 2) with the 1-dB cutofi frequencies of 0.72GHz and 1.45GHz are fabricated and measured. The implemented LPF 2 has 19-dB stopband rejection in the range of 2.05 to 6.36GHz. Finally, two LPF cells (LPF 1 and LPF 2) and an additional connected transmission line are used to construct a new two-stage low-pass fllter (LPF 3) with extended stopband. The measured 16-dB stopband of LPF 3 is up to 7.5GHz while the 1-dB passband range is from DC to 0.67 GHz. The advantages of this proposed low-pass fllter are avoiding any lumped elements and compact layout structure.

A BROADBAND DOUBLY BALANCED MONOLITHIC RING MIXER WITH A COMPACT INTERMEDIATE FREQUENCY (IF) EXTRACTION

To meet the requirements for broadband operation, high port-to-port isolation, and miniature chip area, a doubly balanced monolithic microwave ring mixer with an advanced IF extraction fabricated using 0.15m GaAs pHEMT process is presented. A miniature Marchand-like spiral balun with low-pass fllter is used to extract IF signals and maintain balun performance simultaneously. The low-pass fllter can fllter out both the RF and LO signals. This miniaturized mixer design can mitigate layout complexity, improve port-to-port isolations suitable for ultra-broadband Ku-, K-, and Ka- band applications. Subsequently, the LO/RF-to-IF isolations are greater than 43.2 and 32dB from 11 to 40GHz, respectively. The LO-to-RF isolation is between 26.9 and 50.7dB within the same swept range. The conversion loss is 7.2{12.4dB within the operating bandwidth.

DEVELOPMENT OF A WIDEBAND HIGHLY EFFICIENT GAN VMCD VHF/UHF POWER AMPLIFIER

A 50 to 550MHz wideband gallium nitride (GaN) HEMT power amplifler with over 43dBm output power and 63% drain e-ciency has been successfully developed. The demonstrated wideband power amplifler utilizes two GaN HEMTs and operates in a push-pull voltage mode Class D (VMCD). The design is based on a large signal simulation to optimize the power amplifler's output power and e-ciency. To assure a wideband operation, a coaxial line impedance transformer has been used as part of the input matching network; meanwhile, a wideband a 1:1 ferrite loaded balun and low pass fllters are utilized on the amplifler's output side instead of the conventional serial harmonic termination.

DESIGN OF A MICROSTRIP BALANCED MIXER FOR SATELLITE COMMUNICATION

The design and measured results of a compact, low cost, low conversion loss microstrip single balanced Schottky diodes mixer is proposed. This mixer is designed for Ka-band satellite transponder simulator to convert the 30GHz radio-frequency (RF) signal down to the 20GHz intermediate-frequency (IF) signal with 9.8GHz local oscillator (LO) frequency. This design takes full advantage of the frequency relationship of the RF, IF and LO, which is 3 : 2 : 1. A microstrip rat-race ring is designed at the LO frequency, which also functions as a 180-degree hybrid coupler at the RF frequency by its intrinsic multi-band characteristic. The amplitude and phase balance at both LO and RF frequency are analyzed, which guarantee the state- of-art performance of this single balanced mixer. The multi-function open/short stubs and a lowpass fllter (LPF) with bonding wires across the rat-race ring are optimized to realize this low conversion loss mixer. The measured results show that the conversion loss is less than 9dB at the IF frequency from 20.0 to 21.6GHz, and the power of the second harmonic of LO is i45dBm with +6:5dBm LO drive power. The 3rd order inter-modulation products (IMD3) could be lower than i50dBc with LO power higher than +7:8dBm at the input RF power of i15dBm.