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We present a third-order bandpass threedimensional frequency selective surface (3D FSS) with multiple transmission zeros in this paper. The unit cell of the proposed 3D FSS consists of an air-filled square waveguide and a cuboid dielectric block with three concentric metallic square loops. Due to its inner electromagnetic coupling in the unit cell, this FSS provides a flat passband with three transmission poles, a wide out-of-band rejection with three transmission zeros, and high frequency selectivity. In order to explain the working principle, an equivalent circuit model is established and investigated. Finally, an FSS prototype is fabricated and measured, and the results exhibit good stability for both TE and TM polarizations under incident angles from 0° to 50°. Besides, this FSS has a relatively compact unit cell. [ABSTRACT FROM AUTHOR]

To suppress the undesired signals at the front-ends of wireless systems, a codesign of a simple filtering antenna highly integrated with a slotline-based network is presented and studied in this letter. The proposed antenna integrated with the low-pass filter, the bandpass response is achieved, and impedance bandwidth is also enlarged due to the additional reflection pole contributed by the high integration, which has been evaluated and verified through numerical calculations and full-wave simulations. A design example of the filtering antenna working at 3.5 GHz is developed and fabricated for demonstration purposes. Measured results indicate that good filtering responses with a low insertion loss are achieved. Compared to the original patch antenna, the fractional impedance bandwidth of the proposed one is significantly enhanced, from 6.63% to 13.7%. Besides, harmonics of up to 15.5 GHz are well suppressed. The proposed scheme is simple and compact, exhibiting attractive performance for bandwidth enhancement and spurious suppression applications. [ABSTRACT FROM AUTHOR]

The integrated passive device (IPD) technology has become a new research hotspot, and it depends on electrical characteristics of GaAs, NiCr, and Si3N4 to construct radio frequency (RF) components. RF elements constructed by the IPD technology have features of high quality and ultra-small size, especially for capacitors and inductors. In order to realize the miniaturization of RF circuits, dimensions become as small as possible. Consequently, the layout of a spiral coupled line (SCL) cannot be drawn freely, so that it has uncontrollable odd- and even-mode impedances and a large coupling coefficient, which may limit the design of the traditional Marchand balun negatively. This article solves this problem by designing a GaAs IPD Marchand balun with 1/8-wavelength coupled lines (CLs) and using a capacitor termination to replace the open end in the conventional Marchand balun. Meanwhile, a filter is added to realize a filtering function. The proposed bandpass filtering Marchand balun (BFMB) chip has a size of 1.49 mm $\times1.39$ mm, and measured results indicate that it has an operation band of 2.39–5.68 GHz with a phase imbalance of 5.26° and a magnitude imbalance of less than 0.35 dB. [ABSTRACT FROM AUTHOR]

Based on the alternating direction implicit (ADI) procedure, the complex envelope (CE) method, and the higher order (HO) concept, an unconditionally stable performance-enhanced convolutional perfectly matched layer (CPML) is proposed to efficiently simulate bandpass electromagnetic (EM) devices and signals in the finite-difference time-domain (FDTD) lattice. Through the numerical example, the proposed scheme shows the advantages of the unconditionally stable ADI procedure, HO-CPML scheme, and CE method in terms of absorbing performance, computational efficiency, and bandpass EM simulation. [ABSTRACT FROM AUTHOR]

This paper presents a pathological voice identification system employing signal processing techniques through cochlear implant models. The fundamentals of the biological process for speech perception are investigated to develop this technique. Two cochlear implant models are considered in this work: one uses a conventional bank of bandpass filters, and the other one uses a bank of optimized gammatone filters. The critical center frequencies of those filters are selected to mimic the human cochlear vibration patterns caused by audio signals. The proposed system processes the speech samples and applies a CNN for final pathological voice identification. The results show that the two proposed models adopting bandpass and gammatone filterbanks can discriminate the pathological voices from healthy ones, resulting in F1 scores of 77.6% and 78.7%, respectively, with speech samples. The obtained results of this work are also compared with those of other related published works.

This paper presents a synthesis, design, and simulation of a bandpass rectangular waveguide filter with symmetrical transverse discontinuities operating in the X-band (WR90) with a central frequency of 11GHz, a fractional bandwidth of 3.1%, an undulation ripple of 0.014 dB inside the bandwidth, and a return loss level around 15 dB. The simulation is effectuated under the HFSS environment, where the results of the S-parameters in dB and degree were verified using a CST environment. The obtained results had proven the validity of the conception of our structure since it has shown a symmetrical aspect around the central frequency in both 3D simulators after optimizing the overall dimensions of the irises, also our study has proved that irises are a reliable way to design bandpass filters especially, where their dimensions mainly affect the filter response in terms of the return loss quantity, the insertion loss, and the filter’s bandwidth.

This paper presents a lowpass–bandpass triplexer integrated switch using common lumped-element triple-resonance resonator (LE-TRR) technique. First, a lowpass–bandpass triplexer that has one lowpass channel (LPC) and two bandpass channels (BPCs) is designed. The proposed lowpass–bandpass triplexer design method is different from the conventional lowpass–bandpass multiplexer in which the feeding line is designed with lowpass response to combine bandpass structures to form lowpass–bandpass response. In this design, one branch of LE-TRR together with inductors and capacitors and another two branches of LE-TRR together with classical LC resonators are proposed to constitute one LPC and two BPCs, respectively. The LPC design combines the lowpass transformation method and parameters optimization, and two BPCs can be synthesized by classical coupled-resonator filter design theory. The designed lowpass–bandpass triplexer exhibits extremely compact size of ${\text{0.125}}\lambda _{{\rm{g}}} \times {\text{0.086}}\lambda _{{\rm{g}}}$ , and also has merits of low insertion loss, good return loss, wide bandwidth, and high port-to-port isolation. And then, p-i-n diodes are loaded on the lowpass–bandpass triplexer to realize a lowpass–bandpass triplexer integrated switch that combines both the triplexer and microwave switch function. One LPC and two BPCs are able to be switched on/off separately, and the lowpass–bandpass triplexer integrated switch has eight independent states in total. The off-state suppression of LPC is better than 36 dB, and the off-state suppression of two BPCs are better than 46 and 45 dB, respectively. [ABSTRACT FROM AUTHOR]

In this letter, a novel absorptive structure with a high-transmittance bandpass behavior is proposed based on the electromagnetically induced transparency-like effect. The desired response is achieved by employing cascaded lossy π-shaped and lossless dual-band reflective arrays. The lossy array consists of radiative and subradiant resonators. A resistor is loaded on the radiative resonator to consume the excited current within the stopband. The bright-dark mode coupling contributes to a transparency window with an insertion loss of 0.07 dB. By combining with the reflective array, two absorption bands are obtained at both sides of the passband, and the maximum absorptivity is above 98%. Meanwhile, the 10 dB reflection reduction behavior is realized within the operating band, and a good stealth performance is provided. The fabricated prototype is measured, and the simulation and experimental results are in a good agreement. [ABSTRACT FROM AUTHOR]

A varactor-based fully reconfigurable microstrip bandpass-to-bandpass-with-embedded-stopband filter is presented in this paper. This filter offers wide center frequency and bandwidth tuning flexibility under both bandpass mode and bandpass-with-embedded-stopband mode. The entire tuning ability is based on multiple mode resonator theory and external quality factor tuning structure for bandpass mode and the introduction of transmission zeros (TZs) for bandpass-with-embedded-stopband mode. Under the bandpass mode, the center frequency tuning range is 0.96–1.45 GHz and the bandwidth can be tuned from 0.09 to 1.41 GHz with a fixed center frequency at 1.22 GHz. Under bandpass-with-embedded-stopband mode, the center frequency and bandwidth can be tuned from 0.94 to 1.61 GHz and 0.2–0.33 GHz, respectively. Good agreements are shown between simulated and measured results. [ABSTRACT FROM AUTHOR]

A compact third-order triplexer using a common lumped-element triple-mode resonator (LE-TMR) and LC resonators is presented in this paper. Every channel of proposed third-order triplexer has three resonant modes, i. e. one resonant mode from the common LE-TMR and another two resonant modes from two LC resonators. Step-to-step design procedure is given to guide the third-order triplexer design. As an example, a 0.9/1.8/3.5 GHz third-order triplexer with ripple bandwidths of 150/210/290 MHz is designed, fabricated and measured. The fabricated third-order triplexer has a compact circuit size of 0.163λg × 0.104λg, and high electrical performance can be also acquired. [ABSTRACT FROM AUTHOR]

In this paper a study on designing Triple Band (TB) Bandpass Filter (BPF) by exploiting Triple Mode Resonator (TMR) is presented. By connecting stepped impedance and radial stubs in a categorical manner, a TMR can be obtained which is the basic component for designing this TB BPF. Microstrip lines are tapped over the resonator to work as feed lines and also to generate transmission zeros. The TMRs are Mixed Electric and Magnetic Coupled (MEMC) which help in generating additional Transmission Zeros (TZs) around passbands. As verification, a TB BPF is designed, fabricated and measured. In the designing process, first, a Dual Band (DB) BPF is designed and analyzed completely with the help of even-odd mode analysis. Extraction of lumped component model for the DB BPF is done in order to study the circuit model of the filter. Then the work is extended to design a Triple Band-Band Pass Filter. The fabricated filters offer an advantage in terms of compact size, low insertion loss, good inter band isolation and harmonic suppression. [ABSTRACT FROM AUTHOR]

In this paper, we report the design, analysis, and development of spoof surface plasmon polariton (SSPP)-based reconfigurable band-pass filter using a planar ring resonator. A transition from quasi-transverse electromagnetic (QTEM) mode of microstrip to SSPP mode was implemented which has been subsequently used to develop a reconfigurable band-pass filter. Trapezoidal shape periodically corrugated metallic grooves etched on the planar metallic surface have been used in the implementation of this transition. In the designed transition, impedance and mode matching between QTEM mode and SSPP mode have been achieved using gradient grooves. The developed transition has been used in the characterization of a ring resonator corrugated with the periodical array of the trapezoidal shape grooves. This SSPP ring resonator shows multiple passbands at different frequencies within the specified frequency range. Varactor diodes have been incorporated in the SSPP ring resonator to obtain tunable passband. Three types of varactor-tuned circuits have been experimentally implemented and characterized using SMV2019-079LF diode package. These circuits will pave the path for development of other front-end circuit elements using the concept of spoof SPP. [ABSTRACT FROM AUTHOR]

In this paper a microstrip bandpass filter using cascading technique is presented. The 3 dB passband of this filter extends from 2 GHz to 3.8 GHz. The return loss for this range is below -10 dB. The filter has a fractional bandwidth of 62.06% subject to design frequency of 2.9 GHz for WIFI and WiMAX applications in the range of 2 GHz to 3.8 GHz. The measured results show good agreement with the simulations. The filter is designed on FR4 substrate. The proposed filter has a compact size of λg × 0.3λg, where λg is the guided wavelength at a frequency of 3 GHz. [ABSTRACT FROM AUTHOR]

This paper proposes an 8–12 GHz monolithic power amplifier (PA) with high out-of-band rejection. This PA adopts an impedance conversion technique to reduce the Q of the output impedance of the amplifiers for all stages, which is used to achieve broadband matching performance. In addition, the bandpass matching structures and a trap circuit are adopted to effectively suppress out-of-band signals. The proposed PA is fabricated by using a 0.5 μm GaAs pHEMT process. The measurement results show that the PA has an in-band small signal gain of 23 dB ± 0.7 dB, input and output return loss are both better than −14dB, the saturation output power is about 23dBm, the power-added efficiency (PAE) is better than 20 %, and rejection ratios are 65dBc and 51dBc at 3 GHz and 17 GHz respectively. The area is of 2.3mm × 1.1 mm. [ABSTRACT FROM AUTHOR]

In this paper, the authors introduce a novel fractal-frequency selective surface (F-FSS) geometry for dual-bandpass applications. The centriole-symmetric geometry and dual-band characteristics have been achieved by introducing a golden ratio-based fractal geometry. The characteristic mode and equivalent circuit model analysis of the proposed geometry have been performed. The design offers significant autonomy in controlling the two resonant frequencies separately. Additionally, it demonstrates robust stability against variations in bending angle and polarization. To verify the concept, 7 × 7 array with a dimension of 0. 51 λ 0 × 0. 51 λ 0 × 0. 02 λ 0 (where the free-space wavelength (λ 0) is 39. 20 mm) is simulated, fabricated, and tested in an anechoic chamber. In measurement, the proposed F-FSS geometry achieves notches at 7.74 and 11.80 GHz, with fractional bandwidth of 6.10% and 3.90%, respectively. The design showcases a thickness-bandwidth ratio (T-BR) of 0.62 and 1.54 within their respective frequency bands. The measured results match closely with the simulation results and yield a low RCS value. [ABSTRACT FROM AUTHOR]

An improved feedline configuration for dual-mode resonator filter is investigated in this paper. Based on the introduced topology, a dual-mode dual-band bandpass filter with center frequencies of 1.8 and 2.4 GHz is optimally designed, fabricated and tested. The introduced dual-band bandpass filter has simple structure and enables high selectivity to be realized due to two pairs of transmission zeros located near to the lower and upper passband, respectively. Both measured and simulated performances are presented with good consistency. [ABSTRACT FROM AUTHOR]

Gain enhancement of a wide slot antenna over a wide frequency band using a low profile, second order bandpass frequency selective surface (FSS) as a superstrate is presented in this paper. The proposed multilayered FSS with non-resonant unit cells in each layer allows in-phase transmission of waves radiated from the antenna over a 3dB bandwidth of about 50%. The design allows an enhancement of upto 4dBi in the antenna gain over the entire frequency band (5-8GHz) of operation. The FSS provides a very low insertion loss between the two transmission poles along with a linearly decreasing transmission phase over the band. The composite structure shows an impedance bandwidth (-10dB) of 65% with an average gain between 6-8dBi over the frequency band with a peak gain of 9dBi. Measurement results of the fabricated prototype matches well with the predicted values.

A four-path filter/mixer for surface acoustic wave (SAW)-less frequency division duplex (FDD) radio receivers is proposed, targeting high linearity and compression requirements. A bottom-plate mixing technique improves linearity by reducing the gate-source voltage modulation of the MOSFET switches. Differential bottom-plate mixing allows for switch sharing which halves the effective switch resistance to reduce drain-source voltage modulation. The first four-path switch-RC filter stage with bottom-plate mixing and a shared switch renders 2nd-order voltage-domain RF-bandpass filtering around the LO frequency. Extra out-of-band rejection is implemented combined with $V$ – $I$ conversion and zero-IF frequency down-conversion in the second cross-coupled switch-RC four-path stage, which offers a low-ohmic high-linearity current path for out-of-band interferers. A prototype chip fabricated in a 28-nm CMOS technology achieves an out-of-band IIP3 of +44 dBm, IIP2 of +90 dBm and blocker 1-dB gain-compression point of +13 dBm for a blocker frequency offset of 80 MHz. At this offset frequency, the measured desensitization is only 0.6 dB for a 0-dBm blocker, and 3.5 dB for a 10-dBm blocker at 0.7-GHz LO (i.e., 6- and 9-dB blocker noise figure). The chip consumes 38–96 mW for LO-frequencies of 0.1–2 GHz and occupies an active area of 0.49 mm2. [ABSTRACT FROM AUTHOR]

In this article, a new compact microstrip dual-narrowband bandpass filter is introduced with wide and strong rejection level in the first and last stopband. The location of the second passbands is controllable by a resonator without changing the center frequency of the first passband. The filter structure consists of coupled and stepped transmission lines and radial stubs. Also, fractional 3 dB bandwidth of the first and second passband are 2.35 and 1.62%. The last stopband of the proposed filter is wide. The overall size of the proposed filter is , where is the guided wavelength at the first center frequency. [ABSTRACT FROM AUTHOR]

The realization of planar wideband bandpass filters with an extremely wide upper stopband is described. The filter design differs from conventional approaches in which it is based on the choice of a wideband bandstop (BS) filter, to which a number of shunt-shorted stubs are connected at specific nodes; the stubs provide transmission zeros at the origin. Two examples of wideband bandpass filters with extremely wide upper stopbands are presented: filters based on a fifth-order Chebyshev wideband BS filter and a pseudoelliptic function ultra-wideband-BS filter. Relative passbands in excess of 100% are achieved, while the equivalent of at least four harmonic passbands is suppressed. [ABSTRACT FROM AUTHOR]

A mixer-first receiver (RX) with enhanced selectivity and high dynamic range is proposed, targeting to remove surface acoustic-wave-filters in mobile phones and cover all frequency bands up to 6 GHz. Capacitive negative feedback across the baseband (BB) amplifier serves as a blocker bypassing path, while an extra capacitive positive feedback path offers further blocker rejection. This combination of feedback paths synthesizes a complex pole pair at the input of the BB amplifier, which is upconverted to the RF port to obtain steeper RF bandpass filter roll-off and reduced distortion. This paper explains the circuit principle and analyzes RX performance. A prototype chip fabricated in 45-nm partially depleted silicon on insulator (SOI) technology achieves high out-of-band linearity (input-referred third-order intercept point (IIP3) = 39 dBm and input-referred second-order intercept point (IIP2) = 88 dB) combined with sub-3-dB noise figure. Desensitization due to a 0-dBm blocker is only 2.2 dB at 1.4 GHz. [ABSTRACT FROM AUTHOR]

A new dual-polarized 3-D frequency-selective surface (FSS) with quasi-elliptic bandpass response is proposed by virtue of the square coaxial waveguide (SCW). By utilizing the SCW as one propagation path in the unit cell, two resonators can be generated intrinsically without introducing any extra structures. In addition, the parallel-plate waveguide constructed by sandwiching the ABS frame between outer conductors of adjacent SCWs will provide a second propagation path and create another resonator. With the help of these resonators, a passband with two transmission poles can be obtained. Furthermore, there are two finite transmission zeros locating at both sides of the passband due to the fact that the signals passing through these two propagation paths are combined out of phase, leading to both-sided sharp roll-off skirt. The E-field analysis and equivalent circuit model presented offer a physical insight into the operating principle of the proposed 3-D FSS. For the purpose of validation, the FSS is fabricated through the 3-D printing technique. The measured results exhibit high frequency selectivity, dual polarizations, and stable bandpass response under a variation of the incidence angle. [ABSTRACT FROM PUBLISHER]

We analyze the performance of direct detection receivers with low-order bandpass filtering in terms of achievable rates. Such analysis is of interest in the context of millimeter-wave wireless systems as well as wired and wireless optical links, where low power and low cost are considered to be key requirements. By using a bandpass filter with asymmetric passband transfer function of low order ( $1/f$ roll-off rate) prior to the intensity detection device (a diode or photodiode), we show that the ideal Shannon data rate attainable with coherent receivers can still be asymptotically approached with simple filtering and direct detection. We also discuss practical aspects that partially limit this remarkable behavior, and show that gains are still possible compared with conventional direct detection. [ABSTRACT FROM PUBLISHER]

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A switchable bandpass filter is presented in this paper, which is able to operate at two different frequencies. The “open-ring” resonators and cantilever microelectromechanical systems (MEMSs) switches are employed to form the switchable filter with a high rejection at out-of passband and a controlled dc bias of 26 V. A hybrid resonance circuit with both series circuit and parallel circuit are used as the equivalent circuit, which is used to accurately analyze the structure parameters. The MEMS switch capacitance, used for equivalent circuit and driving voltage estimation, is analyzed to achieve an exact predicted value by equivalent microstrip line model. The isolation of designed MEMS switch is greater than 40 dB with awideband from4 to 9GHz, the filter is switched on and off to achieve the center frequency at ~7.81 and ~8.35 GHz separately. The filter is fabricatedon high-resistance silicon, and the measured results showed a good agreement with the simulated results. The filter performance shows a sharp rejection greater than 40dB at the frequency of ( \textsf f { {{\textsf {0}}}} \pm 0.5 GHz), and the insertion loss is >−3.4 dB in the passband. [ABSTRACT FROM PUBLISHER]

This paper presents a planar tri-band bandpass filter with high out-of-band rejection over a wide band. The filter is based on two pairs of λ/4 resonators embedded inside an open loop ring resonator without any size increase, where each pair of resonators are electromagnetically coupled to each other and the feedlines. This results in the excitations of passbands, where the first passband is generated by the open loop resonators. The second and the third passbands are excited by λ/4 resonators. The proposed technique provides sufficient degrees of freedom to control the center frequency and bandwidth of the three passbands independently. In addition, the six transmission zeros created around the passbands results in a tri-band filter with high selectivity, sharp 3 dB cut-off frequency, high isolation, low passband insertion-loss and high out-of-band harmonic rejection across an ultra-broadband frequency range up to 17 GHz. The proposed technique has the ability to switch from triple to dual band by removing one pair of the inner resonators. Design methodology and simulation results of the filter are provided. [ABSTRACT FROM AUTHOR]

A novel type of compact and high selectivity dual-band bandpass filter (BPF) incorporating a dual-mode defected ground structure resonator (DDGSR) and a dual-mode open-stub loaded stepped impedance resonator (DOLSIR) is proposed in this paper. Utilizing capacitive source-load coupling and the intrinsic characteristics of the two types of dual-mode resonators, compact dual-band BPF with multi transmission zeros near the passband edges as well as a wide stopband which can be used to achieve high selectivity is realized. An experimental dual-band BPF located at 2.4 and 3.2 GHz was designed and fabricated. The validity of the design approach is verified by good agreement between simulated and measurement results.

A metal–semiconductor–metal photodetector (PD) whose detection wavelength can be modulated was fabricated using a MgxZn1-xO/ZnO bilayer. By varying the MgxZn1-xO layer thickness (50–400 nm), we modulated the detection wavelength from lowpass to bandpass. For a thin (50 nm) MgxZn1-xO film, most short-wavelength (less than 340 nm) incident photons—more than 69%—passed through the MgxZn1-xO and were absorbed by ZnO, causing a higher photoresponse in the short-wavelength region and thus a low-pass PD. As the thickness of the MgxZn1-xO film increased, the short-wavelength photoresponse was gradually suppressed, and a bandpass PD was achieved. A thicker (400 nm) MgxZn1-xO film absorbed more short-wavelength (less than 340 nm) incident photons, leaving only 5.5% of the incident photons to be absorbed by the ZnO layer underneath. This reduced the short-wavelength photoresponse, yielding a bandpass PD with a detection wavelength of 325–360 nm. Although the short-wavelength (less than 340 nm) incident photons were absorbed by MgxZn1-xO, few photogenerated electron–hole pairs contributed to the photoresponse; instead, they were trapped by the defects in MgxZn1-xO because of its poor crystalline quality. [ABSTRACT FROM PUBLISHER]

In this article, copper zinc phosphate glass doped with 5 % barium oxide has an amazing optical property due to its application as bandpass filters. Typically, the glass conventional casting with chemical composition 42PO-(14- x)NaO-39ZnO-5BaO- xCuO where ( x = 2, 4, 6, 8 and 10) was formed. The density was measured using the conventional Archimedes method and the molar volume was calculated. The change of glass structure was investigated using X-ray diffraction analysis (XRD). Distinctly, the results revealed that no crystal growth in all glass systems was observed. The density of glass samples was increased whereas the molar volume was decreased with increasing copper content. The absorption, transmission and reflection were measured and some other optical properties were calculated like UV cut-off, and IR cut-off. For instance, the visible cut-off started from 462 to 532 nm while the IR bonds were initiated at 630 to 1200 nm with 6 to 10 % CuO concentration. [ABSTRACT FROM AUTHOR]

A novel dual-mode bandpass filter with wide stopband using capacitance loaded square meander loop resonator is presented. The resonator can exhibit dispersion effect due to loaded capacitance, which can reduce the size of resonator and suppress harmonic. The disturbed degenerate-mode resonances are used to form the passband while two transmission zeroes are generated on each side of the passband so as to obtain high selectivity. The circuit area of bandpass filter is only 0.14λg × 0.14λg, where λg is the guided wavelength at the center frequency. The measured result reaches good agreement with simulated result. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, the authors proposed a bandpass frequency selective surface using the slot four arms star geometry. An expression to calculate the resonance frequency is introduced, for which results with difference <6%, when compared to measured ones, were obtained. The polarization dependence was discussed and a model based on two independent equivalent structures was successfully presented. Three prototypes were designed, fabricated, and characterized. A good agreement between simulated and measured results is observed. With the asymmetrical geometry, two bandpass bandwidths, separated by a notch band-rejection, were achieved, a suitable characteristic to avoid co-channel interferences. Furthermore, if an orthogonal polarization is applied, this notch band-rejection can be converted to a bandpass bandwidth, providing a polarization filter behavior. The geometry simplicity and observed frequency response make the proposed FSS potentially attractive for many telecommunication systems. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1105-1109, 2016 [ABSTRACT FROM AUTHOR]

A center frequency reconfigurable continuous-time bandpass \Delta \Sigma modulator is implemented in 65 nm CMOS. A new duty-cycle-controlled DAC scheme facilitates center frequency reconfiguration, and also reduces power consumption and die area by halving the total number of DACs in the modulator. A prototype sixth-order modulator, sampling at 800 MS/s, achieves a measured 69 dB SNDR over a 25 MHz bandwidth around a 200 MHz center frequency. The center frequency of the prototype bandpass \Delta \Sigma modulator can be varied from 180 to 220 MHz. The total power consumption is 35 mW and the die area is 0.25 \textmm^2. This modulator scheme facilitates receivers that support multiple channels over a wide range of frequencies. [ABSTRACT FROM PUBLISHER]

A general cascaded filter design technique is implemented to get a tunable narrow-band filter response based on the general Chebyshev bandpass filter. A cavity combline microwave filter is fabricated by cascading two asymmetrical filters without using an isolator between them. Tuning is provided by means of the screws on top of each resonator of the cavity combline filter. An optimization is applied to get the desired response. The designed example is presented together with the simulation and measurement results. The measured data are in good agreement with the simulation results. [ABSTRACT FROM PUBLISHER]

This paper reports on the implementation of a closed-loop readout concept for a vibratory MEMS gyroscope. The system is based on electro-mechanical (el.-mech.) ΔΣ-modulation and implemented on an integrated circuit (ASIC) with incorporation of a field programmable gate array (FPGA) for rapid prototyping. The sense loop exhibits two modulation stages for the detection of the Coriolis-signal and thus reduces the sampling frequency (f s ) by a factor of 4 and 100 compared to bandpass- and conventional lowpass modulators, respectively. This concept enables the design of low-power interfaces with very low f s , reducing the power consumption in the analog and digital domain. Measurements results of the readout circuit are presented using a MEMS gyroscope,whichdemonstrates the functionality and competitiveness of the concept. [ABSTRACT FROM AUTHOR]

Typical reverberant chambers used for High Intensity Acoustic Testing (HIAT) can achieve high sound pressure levels (SPL) across most of the applicable frequency range (20 Hz to 10 kHz), but they have limitations. Depending on the size of the chamber, low frequency chamber modes may be limited in the testing frequency range. In addition, reverberant chambers that use conventional 1/3-Octave controllers are not able to control low frequency chamber modes as effectively as the higher frequencies. A typical response to this inability to control the chamber modes is to high pass the frequency range of the excitation in the chamber to prevent exciting the low frequency modes. This method protects the test article from over-testing, although it also might under-test an article that has a fundamental mode below the high-pass frequency of the chamber. Recently, Maryland Sound International conducted a test at the Naval Research Laboratory (NRL) to determine if Direct Field Acoustic Testing (DFAT) technology could be applied to conventional reverberant chambers. [ABSTRACT FROM AUTHOR]

In this paper, a novel Doherty power amplifier (DPA) configuration with an auxiliary transformer is proposed for broadband operation. Theoretical analysis reveals that the proposed design can offer enhanced power utilization factor (PUF) and wideband Doherty behavior. The optimal design of the auxiliary transformer is identified with an aim to provide good impedance matching and minimal group delay. Based on the proposed theory, a 1.6–2.4-GHz 20-W DPA with improved PUF is designed, simulated, and measured. Under continuous wave excitation, measurement results indicate that the proposed DPA can achieve a PUF of 0.9, good Doherty behavior over the entire frequency band with a 6-dB back-off efficiency of 55%–64%, and saturated efficiency of 68%–76%. In addition, by the use of single-carrier WCDMA signal (centered at 2 GHz) with peak-to-average power ratio of 6.6 dB and at an average output power of 37 dBm, an average drain efficiency of 56% is obtained with adjacent channel leakage power ratio of better than -37 dBc. [ABSTRACT FROM PUBLISHER]

In conventional multiplexer designs that use a direct-feed filter in each channel selection, matching circuits are typically crucial for achieving low loading effects between channel circuits. However, existing matching designs are often complex, and time-consuming optimizations are required when the number of multiplexer channels exceeds three. This paper proposes and verifies two four- and one five-channel multiplexers with simple and effective matching designs. [ABSTRACT FROM PUBLISHER]

Gain enhancement of a wide slot antenna over a wide frequency band using a low profile, second order bandpass frequency selective surface (FSS) as a super-strate is presented in this paper. The proposed multilayered FSS with non-resonant unit cells in each layer allows in-phase transmission of waves radiated from the antenna over a 3dB bandwidth of about 50%. The design allows an enhancement of up to 4 dBi in the antenna gain over the entire frequency band (5-8 GHz) of operation. The FSS provides a very low insertion loss between the two transmission poles along with a linearly decreasing transmission phase over the band. The composite structure shows an impedance bandwidth (-10 dB) of 65% with an average gain between 6-8 dBi over the frequency band with a peak gain of 9 dBi. Measurement results of the fabricated prototype matches well with the predicted values. [ABSTRACT FROM AUTHOR]