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Microwave Theory and Techniques, IEEE Transactions on

Issue 5 • Date May 2007

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Displaying Results 1 - 25 of 36
  • Table of contents

    Publication Year: 2007 , Page(s): C1 - C4
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  • IEEE Transactions on Microwave Theory and Techniques publication information

    Publication Year: 2007 , Page(s): C2
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  • Pruning the Volterra Series for Behavioral Modeling of Power Amplifiers Using Physical Knowledge

    Publication Year: 2007 , Page(s): 813 - 821
    Cited by:  Papers (31)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (695 KB) |  | HTML iconHTML  

    This paper presents an efficient and effective approach to pruning the Volterra series for behavioral modeling of RF and microwave power amplifiers. Rather than adopting a pure "black-box" approach, this model pruning technique is derived from a physically meaningful block model, which has a clear linkage to the underlying physical behavior of the device. This allows all essential physical properties of the PA to be retained, but significantly reduces model complexity by removing unnecessary coefficients from the general Volterra series. A reduced-order model of this kind can be easily extracted from standard time/frequency-domain measurements or simulations, and may be simply implemented in system-level simulators. A complete physical analysis and a systematic derivation are presented, together with both computer simulations and experimental validations View full abstract»

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  • Modeling Superconducting Transmission Line Bends and Their Impact on Nonlinear Effects

    Publication Year: 2007 , Page(s): 822 - 828
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (518 KB) |  | HTML iconHTML  

    This paper reports on a numerical technique to obtain the current distribution in the annular bent sections of planar layouts. This is used to obtain the linear and nonlinear circuit distributed parameters modeling a superconducting strip bend and its impact on intermodulation distortion. As an example, we analyze a superconductive open-loop resonator and assess the linear and nonlinear contribution of its bends in its overall linear and nonlinear performance. These simulations are very useful for optimizing the resonators of a filter in order to minimize its nonlinear distortion View full abstract»

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  • Analytic Large-Signal Modeling of Silicon RF Power MOSFETs

    Publication Year: 2007 , Page(s): 829 - 837
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (737 KB) |  | HTML iconHTML  

    This paper provides novel analytic expressions and methodology for predicting the large-signal gain of RF power MOSFETs. The expressions are derived from a model that includes input and output matching impedances, source inductance, and gate resistance. Using the load line concept superimposed on a nonlinear current generator, this paper demonstrates reasonably accurate predictions of gain and gain compression point View full abstract»

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  • A High-Directivity Combined Self-Beam/Null-Steering Array for Secure Point-to-Point Communications

    Publication Year: 2007 , Page(s): 838 - 844
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1135 KB) |  | HTML iconHTML  

    A high-directivity combined self-beam/null-steering array for secure point-to-point binary phase-shift keying communications is introduced. The system provides high directivity and reduced probability of interception using just two antenna elements. Using quadrature phase-shift keying modulators allows for compact single-layer fabrication. The 2.4-GHz prototype is tested at interrogation angles of 0deg, -10deg, and +20deg, and demonstrates high signal-to-interference ratio directivity, completely disabling interception plusmn20deg from the direction of the interrogator. The system should find various applications where secure communications are required View full abstract»

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  • Polar SiGe Class E and F Amplifiers Using Switch-Mode Supply Modulation

    Publication Year: 2007 , Page(s): 845 - 856
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1291 KB) |  | HTML iconHTML  

    Two integrated polar supply-modulated class E and F power amplifiers (PAs) in 0.18-mum SiGe BiCMOS process are presented. The amplifiers are used to transmit GSM-EDGE signals with an envelope dynamic range of 11 dB and a frequency range of 880-915 MHz. The amplifiers use switch-mode dc-dc buck converters for supply modulation, where sigma-delta (SigmaDeltaM), delta (DeltaM), and pulsewidth modulation are used to modulate the PA amplitude signal. A framework has been developed for comparing the three switching techniques for EDGE implementation. The measurement results show that DeltaM gives the highest efficiency and lowest adjacent channel power, providing class E and F PA efficiencies of 33% and 31%, respectively, at maximum EDGE output power. The corresponding class E and F linearized amplifiers' output spectra at 400-kHz offset are -54 and -57dBc, respectively View full abstract»

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  • A 23-dBm 60-GHz Distributed Active Transformer in a Silicon Process Technology

    Publication Year: 2007 , Page(s): 857 - 865
    Cited by:  Papers (37)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1534 KB) |  | HTML iconHTML  

    In this paper, a distributed active transformer for the operation in the millimeter-wave frequency range is presented. The transformer utilizes stacked coupled wires as opposed to slab inductors to achieve a high coupling factor of kf=0.8 at 60 GHz. Scalable and compact equivalent-circuit models are used for the transformer design without the need for full-wave electromagnetic simulations. To demonstrate the feasibility of the millimeter-wave transformer, a 200-mW (23 dBm) 60-GHz power amplifier has been implemented in a standard 130-nm SiGe process technology, which, to date, is the highest reported output power in an SiGe process technology at millimeter-wave frequencies. The size of the output transformer is only 160times160 mum2 and demonstrates the feasibility of efficient power combining and impedance transformation at millimeter-wave frequencies. The two-stage amplifier has 13 dB of compressed gain and achieves a power-added efficiency of 6.4% while combining the power of eight cascode amplifiers into a differential 100-Omega load. The amplifier supply voltage is 4 V with a quiescent current consumption of 300 mA View full abstract»

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  • A Mixed-Signal Approach Towards Linear and Efficient N-Way Doherty Amplifiers

    Publication Year: 2007 , Page(s): 866 - 879
    Cited by:  Papers (32)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (848 KB) |  | HTML iconHTML  

    A mixed-signal approach for the design and testing of high-performance N-way Doherty amplifiers is introduced. In support of this, an analysis of N-way power-combining networks is presented-in particular, their optimum design-by examining the relationship between the drive conditions of the active devices and input power. This analysis makes no prior assumption on the network topology and facilitates free-to-choose levels for the high-efficiency power back-off points. By comparing the results of this analysis with prior work, it is shown that very specific drive conditions apply to traditional three-way Doherty amplifier implementations to obtain simultaneously high-efficiency and high-linearity operation. To support these conclusions, a 15-W three-way Doherty amplifier was constructed using Philips GEN4 LDMOS devices featuring three separate inputs to independently drive the main and peaking devices. By testing this three-way amplifier with a custom-built measurement setup, capable of providing multiple digitally controlled coherent RF input signals with high spectral purity, a unique flexible amplifier concept is created resulting in a record-high efficiency for LDMOS-based Doherty amplifiers over a 12-dB back-off power range View full abstract»

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  • GaInP/GaAs HBT Sub-Harmonic Gilbert Mixers Using Stacked-LO and Leveled-LO Topologies

    Publication Year: 2007 , Page(s): 880 - 889
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (862 KB) |  | HTML iconHTML  

    This paper discusses and demonstrates the most popular sub-harmonic Gilbert mixers in 2-mum GaInP/GaAs HBT technology. High two local oscillators (2LO)-to-RF isolation is important to alleviate the self-mixing problem of the sub-harmonic mixer. The demonstrated GaInP/GaAs HBT stacked-local oscillator (LO) mixer topology has achieved the best 2LO-to-RF isolation when compared with the previous literature. On the other hand, the leveled-LO sub-harmonic mixers have advantages in terms of the high speed and low dc supply voltage at the cost of much larger LO pumping power. Among all the structures, the bottom-LO sub-harmonic mixer has the lowest current consumption and the simplest circuit structure at the expense of the 2LO-to-RF isolation View full abstract»

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  • Design of High-Performance Millimeter Wave and Sub-Millimeter Wave Quasi-Optical Isolators and Circulators

    Publication Year: 2007 , Page(s): 890 - 898
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (547 KB) |  | HTML iconHTML  

    Faraday rotators using permanently magnetized ferrite materials are used to make quasi-optical isolators and circulators at millimeter wave and sub-millimeter wave frequencies that have far higher performance than their waveguide equivalents. This paper demonstrates state-of-the-art performance for four-port quasi-optical circulators with 60-dB isolation, 0.2-dB insertion loss, and better than 80-dB return loss for devices centered at 94 GHz. A method is presented for the accurate characterization of the complex permeability and permittivity of permanently magnetized ferrites via a series of frequency and polarization dependent transmission and reflection measurements. The dielectric and magnetic parameters for the sample are determined by fitting theoretical curves to the measured data. These fitted parameters are then used in a model for a complete quasi-optical Faraday rotator, including matching layers, allowing the accurate design and fabrication of these devices for any specific operational frequency band in the millimeter wave and sub-millimeter wave regime. Examples are given showing typical results and demonstrating how temperature cycling can significantly improve the temperature stability of these devices, while allowing fine tuning of the center frequency. We also indicate the performance possible at higher frequencies to above 1 THz and outline performance of truly planar isolators where lossy polarizer material is built into the Faraday rotator matching structure View full abstract»

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  • Millimeter-Wave Transition From Waveguide to Two Microstrip Lines Using Rectangular Patch Element

    Publication Year: 2007 , Page(s): 899 - 905
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (732 KB) |  | HTML iconHTML  

    A millimeter-wave transition from a waveguide to two microstrip lines and the design methodology are proposed. A rectangular patch element in a short-terminated waveguide is analyzed by the cavity model of a patch antenna and the dyadic Green's function of the waveguide. The analysis points out that the rectangular patch element has an optimum width for wideband, which only has the function of the broad wall width of the waveguide. The transition also works as a divider. A numerical investigation of a transition having two microstrip lines validates the analytical model in terms of wideband, and indicates that the distance between the two microstrip lines has an optimum length for suppressing higher order modes. A prototype transition exhibits an insertion loss of 0.5 dB from 76 to 77 GHz, and a bandwidth of 6.9% (5.29 GHz) for the reflection coefficient below -15 dB for the waveguide port View full abstract»

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  • RF Front-End Passive Circuit Implementation Including Antenna for ZigBee Applications

    Publication Year: 2007 , Page(s): 906 - 915
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1707 KB) |  | HTML iconHTML  

    This paper presents a front-end passive circuit module for ZigBee applications using low-temperature co-fired ceramic technology. The front-end part consists of an antenna, a bandpass filter, a switch, and two baluns. In antenna design, the solenoid shape is employed for reducing the size of the antenna, resulting in an overall size of 9times16.4times1.82 mm3 and a gain of -1.4 dBi. As for the filter, two types of filters are suggested. First, the lumped-type filter employing a high-Q spiral inductor has more than 20-dB attenuation at both stopbands, very near to the passband. Secondly, the semilumped-type filter adopting an edge coupled line and a loading capacitor provides a group delay of below 5 ns and is adequate for the full module structure due to the structure flexibility. A balun is evaluated using lumped components instead of a transmission line and, thus, it provides an insertion loss of only 0.3 dB and a phase difference of 180deg between balanced signals. Based on these components, an RF front-end module including attaching pads for an RF integrated circuit (IC) and baseband IC is implemented. In case of using the lumped-type filter, the insertion loss of the front-end module is 6.5 dB, and the group delay is below 7 ns. In case of adopting the semilumped-type filter, the insertion loss is 6.2 dB, and the group delay is below 4 ns. The overall size of the former and latter is 25.14times28.5times0.68 mm3 and 25.66times25.58times1.17 mm3, respectively View full abstract»

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  • Wideband Design of the Fully Integrated Transmitter Front-End With High Power-Added Efficiency

    Publication Year: 2007 , Page(s): 916 - 924
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1652 KB) |  | HTML iconHTML  

    A novel approach to enhance power-added efficiency (PAE) bandwidth and transmitting power bandwidth of the fully integrated transmitter front-end is proposed. To obtain these characteristics, a wideband multifunctional antenna operating as an output matching load of the power transistor and harmonic tuning circuits, as well as a radiator, is designed and fully integrated with a power transistor. Therefore, the wideband direct integration between the output of the power transistor and input of the antenna can be achieved without any impedance transformers. Under the condition of PAE over 50% and transmitting power within 3 dB for the peak transmitting power at the operating band, the measured PAE bandwidth and transmitting power bandwidth are 930 MHz (from 4.9 to 5.83 GHz) and 1030 MHz (from 4.8 to 5.83 GHz), respectively. About a half size is also obtained compared with the conventional wideband class F active antenna for high PAE, and the second and third harmonic radiations of the proposed structure for the normalized peak power of the fundamental frequency are measured less than -30 and -40 dB in all directions, respectively View full abstract»

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  • Weighted Polynomial Digital Predistortion for Low Memory Effect Doherty Power Amplifier

    Publication Year: 2007 , Page(s): 925 - 931
    Cited by:  Papers (15)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1432 KB) |  | HTML iconHTML  

    We have proposed a simple and effective weighted polynomial digital predistortion algorithm, which consists of weighting, least square polynomial fit, and de-weighting. The weighting factor is introduced to describe the signal distribution statistics and high harmonic generation at a high power region to improve accuracy of the error function. A low memory linear Doherty power amplifier (PA) has been realized with two 90-W peak envelope power LDMOSFETs using memory effect reduction techniques, and the proposed algorithm has been applied to the PA. For the forward-link wideband code division multiple access 3FA signal, the adjacent channel leakage ratio performance at 5-MHz offset is -56 dBc with power-added efficiency of 20.78% at an average power of 40 dBm. The proposed weighting polynomial algorithm provides a significantly reduced error power and superior convergence behavior with improved linearization capability than the conventional polynomial. Moreover, the low memory Doherty amplifier could be linearized for a wideband signal using the simple algorithm without any memory effect compensation View full abstract»

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  • Adaptive Digital Feedback Predistortion Technique for Linearizing Power Amplifiers

    Publication Year: 2007 , Page(s): 932 - 940
    Cited by:  Papers (53)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1049 KB) |  | HTML iconHTML  

    We have developed a new adaptive digital predistortion (DPD) linearization technique based on analog feedback predistortion (FBPD). The lookup-table-based feedback input can remove the bandwidth limitation of the feedback circuit related to the loop delay, and suppress feedback oscillation by accurate digital control of the feedback signal. Moreover, the predistortion (PD) signal can be extracted very efficiently. By combining the feedback linearization and DPD linearization techniques, the performance of the predistorter is enhanced significantly compared to the conventional DPD. To clearly visualize the characteristics of digital FBPD (DFBPD), we have compared it to the conventional DPD based on the recursive least square algorithm using Matlab simulation. The results clearly show that the new method is a good linearization algorithm, better than a conventional DPD. For the demonstration, a Doherty power amplifier with 180-W peak envelope power is linearized using the proposed DFBPD. For a 2.14-GHz forward-link wideband code-division multiple-access signal, the adjacent channel leakage ratio at 2.5-MHz offset is -58 dBc, which is improved by 15 dB at an average output power of 43 dBm View full abstract»

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  • Hybrid S-Parameters for Transmission Line Networks With Linear/Nonlinear Load Terminations Subject to Arbitrary Excitations

    Publication Year: 2007 , Page(s): 941 - 950
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (860 KB) |  | HTML iconHTML  

    We propose a generalized S-parameter analysis for transmission lines (TLs) with linear/nonlinear load terminations subject to arbitrary plane-wave and port excitations. S-parameters are prevalently used to model TLs such as cable bundles and interconnects on printed circuit boards (PCBs) subject to port excitations. The conventional S-parameter approach is well suited to characterize interactions among ports. However, nontraditional port excitations associated with plane-wave coupling to physical ports at TL terminals lead to forced, as well as propagating, modal waves, necessitating a modification of the standard S-parameter characterization. In this paper, we consider external plane-wave excitations, as well as port (internal) sources, and propose a hybrid S-parameter matrix for characterization of the associated microwave network and systems. A key aspect of the approach is to treat the forced waves at the ports as constant voltage sources and induced propagating modal waves as additional entries (hybrid S-parameters) in the S-parameter matrix. The resulting hybrid S-matrix and voltage sources can be subsequently exported to any circuit solver such as HSPICE and Agilent's Advanced Design System for the analysis of combined linear and nonlinear circuit terminations at ports. The proposed method is particularly suited for susceptibility analysis of cable bundles and PCBs for electromagnetic interference evaluations. It also exploits numerical techniques for structural and circuit domain characterization and allows for circuit design optimization without a need to perform any further computational electromagnetic analysis View full abstract»

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  • Compact Waveguide-Based Power Divider Feeding Independently Any Number of Coaxial Lines

    Publication Year: 2007 , Page(s): 951 - 957
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (820 KB) |  | HTML iconHTML  

    The device described in this paper has been designed to enable the feeding of many individual plasma sources from a single microwave generator, providing a noninterfering and constant supply of power to each coaxial line driving these plasma sources. The power coming from the generator flows through a waveguide under standing-wave conditions provided by the presence of a conducting plane located at the waveguide end opposite that linked to the generator. Power is extracted from the waveguide, at the maximum of intensity of the E-field standing wave, by a waveguide-to-coaxial-line transition designated as a probe. One or two probes can be set at each such maximum of field intensity (and this on both sides of the waveguide wide wall), yielding a compact power divider. Each coaxial line feeds a microwave field applicator, sustaining plasma, through a matching circuit comprising a tuning means and a ferrite isolator (circulator with a matched load), the latter ensuring that whatever happens to the plasma source, the other feeding lines are not affected. The conditions required for a perfect match of the microwave generator to the power divider are elaborated and examples of actual designs are presented View full abstract»

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  • An Efficient Scheme for Processing Arbitrary Lumped Multiport Devices in the Finite-Difference Time-Domain Method

    Publication Year: 2007 , Page(s): 958 - 965
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB) |  | HTML iconHTML  

    Developing full-wave simulators for high-frequency circuit simulation is a topic many researchers have investigated. Generally speaking, methods invoking analytic pre-processing of the device's V-I relations (admittance or impedance) are computationally more efficient than methods employing a numerical procedure to iteratively process the device at each time step. For circuits providing complex functionality, two-port or possibly multiport devices whether passive or active, are sure to appear in the circuits. Therefore, extensions to currently available full-wave methods for handling one-port devices to process multiport devices would be useful for hybrid microwave circuit designs. In this paper, an efficient scheme for processing arbitrary multiport devices in the FDTD method is proposed. The device's admittance is analytically pre-processed and fitted into one grid cell. With an improved time-stepping expression, the computation efficiency is further increased. Multiport devices in the circuit can be systematically incorporated and analyzed in a full-wave manner. The accuracy of the proposed method is verified by comparison with results from the equivalent current-source method and is numerically stable View full abstract»

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  • Genetic Algorithm in Reduction of Numerical Dispersion of 3-D Alternating-Direction-Implicit Finite-Difference Time-Domain Method

    Publication Year: 2007 , Page(s): 966 - 973
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (582 KB) |  | HTML iconHTML  

    A new method to reduce the numerical dispersion of the 3-D alternating-direction-implicit finite-difference time-domain method is proposed. Firstly, the numerical formulations are modified with the artificial anisotropy, and the new numerical dispersion relation is derived analytically. Moreover, theoretical proof of the unconditional stability is shown. Secondly, the relative permittivity tensor of the artificial anisotropy can be obtained by the adaptive genetic algorithm. In order to demonstrate the accuracy and efficiency of this new method, several examples are simulated. The numerical results and the computational requirements of the proposed method are then compared with those of the conventional method and measured data. In addition, the reduction of the numerical dispersion is investigated as the objective function of the genetic algorithm. It is found that this new method is accurate and efficient by choosing a proper objective function View full abstract»

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  • Robust Formulations of the Cauchy Method Suitable for Microwave Duplexers Modeling

    Publication Year: 2007 , Page(s): 974 - 982
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB) |  | HTML iconHTML  

    It is well known that a Vandermonde matrix generates an ill-conditioned system matrix when applied with finite numerical precision. This deficiency affects the Cauchy method by restricting its application to only lower order systems. This paper presents innovative, accurate, and robust formulations of the Cauchy method to rectify this limitation and make the Cauchy method suitable for the extraction of a high-order microwave duplexer polynomial model. The techniques employed are: the change of polynomial basis into the Krylov subspace and the precondition technique, both acting on the system matrix of the classic Cauchy method formulation. A novel formulation using the QR algorithm on the two characteristic functions of the duplexer and a suitable combination of the QR method and the precondition technique are then presented. Each of these procedures has been successfully verified by numerical application examples View full abstract»

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  • A 3-D Spectral-Element Time-Domain Method for Electromagnetic Simulation

    Publication Year: 2007 , Page(s): 983 - 991
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    A spectral-element time-domain (SETD) method is proposed to solve 3-D transient electromagnetic problems based on Gauss-Lobatto-Legendre polynomials. It has the advantages of spectral accuracy and block-diagonal mass matrix. With the inexpensive inversion of the block-diagonal mass matrix, the proposed method requires only a trivial sparse matrix-vector product at each time step, thus significantly reducing CPU time and memory requirement. Galerkin's method is used for spatial discretization, and a fourth-order Runge-Kutta scheme is employed for the time integration. The perfectly matched layer (PML) is employed to truncate the boundary in unbounded problems. The pseudospectral time-domain method is used to simplify the treatment of the PML inside the proposed SETD method. Numerical examples are shown to verify the efficiency and the spectral accuracy with the order of basis functions View full abstract»

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  • Modeling and Fabrication of CMOS Surface Acoustic Wave Resonators

    Publication Year: 2007 , Page(s): 992 - 1001
    Cited by:  Papers (10)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1825 KB) |  | HTML iconHTML  

    A fully integrated two-port surface acoustic wave (SAW) resonator, fabricated using a standard 0.6-mum complementary metal-oxide semiconductor (CMOS) process is described in this paper. Only three micromachining processes, namely, reactive ion etching, zinc-oxide deposition, and wet etching, implemented subsequent to the standard process, are required to realize these resonators. Three design examples of these resonators are given to demonstrate the characteristics of these resonators at different operating frequencies. Experimental measurements of the S21 transmission characteristics were conducted on the fabricated resonators and they were found to have parallel resonant frequencies of 1.02 GHz, 941 MHz, and 605 MHz and quality (Q) factors of 44, 86, and 285, respectively. Based on these measurements and the fabrication layers of the device, an equivalent-circuit model tailored specifically for standard CMOS two-port resonators was developed. Finite-element modeling of the SAW resonators was performed to verify the measured series resonant frequency. Comparison between the developed model and measurement characteristics was also presented. Improvement in Q factor was observed when reflector height was increased View full abstract»

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  • Dual-Band Filter Design With Flexible Passband Frequency and Bandwidth Selections

    Publication Year: 2007 , Page(s): 1002 - 1009
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (737 KB) |  | HTML iconHTML  

    In this paper, improved dual-band filter design is studied. The dual-band resonators are composed of shunt open- and short-circuited stubs. In order to fulfil the requirements of dual-band inverters, a structure of stepped-impedance asymmetric coupled lines is proposed and its equivalent circuit is also derived. The dual-band filter is then designed based on this equivalent circuit. This type of filter can achieve relatively large practical passband center frequency ratios (in theory infinite), and it has more freedom of bandwidth ratio. The circuit size is also reduced. Detailed design procedure is presented and, finally, a filter example is given to validate the theoretical study View full abstract»

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  • A Direct Synthesis Approach for Microwave Filters With a Complex Load and Its Application to Direct Diplexer Design

    Publication Year: 2007 , Page(s): 1010 - 1017
    Cited by:  Papers (18)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (741 KB) |  | HTML iconHTML  

    This paper presents a direct synthesis approach for general Chebyshev filters terminated with a complex load. The new approach is based on the fact that the polynomial functions for synthesizing the filters are composed for any matched loads. By normalizing the polynomial functions with assumed complex matched load impedance by a real reference load impedance using power waves normalization, a set of new polynomial functions for the same filter, but with real load impedance, can be formulated, from which the coupling matrix for the physical filter design can be obtained using a standard direct filter synthesis approach. This new direct synthesis approach can find many applications. A practical application is the direct diplexer design with a realistic junction model being taken into account. With the diplexer design is concerned, a fast-converged iterative scheme is proposed. The effectiveness and the validation of the proposed scheme are demonstrated by two design examples View full abstract»

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The IEEE Transactions on Microwave Theory and Techniques focuses on that part of engineering and theory associated with microwave/millimeter-wave components, devices, circuits, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals. This includes scientific, technical, and industrial, activities. Microwave theory and techniques relates to electromagnetic waves usually in the frequency region between a few MHz and a THz; other spectral regions and wave types are included within the scope of the Society whenever basic microwave theory and techniques can yield useful results. Generally, this occurs in the theory of wave propagation in structures with dimensions comparable to a wavelength, and in the related techniques for analysis and design..

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