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Microwave and Wireless Components Letters, IEEE

Issue 9 • Date Sept. 2003

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Displaying Results 1 - 21 of 21
  • An X- to ku-band 3-bit digital MEMS varactor

    Publication Year: 2003 , Page(s): 361 - 363
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (575 KB) |  | HTML iconHTML  

    A 3-bit digital microelectromechanical system (MEMS) varactor bank is demonstrated on a low-cost glass substrate. It is composed of three discrete-position varactors, each of them achieving a capacitance ratio close to 3:1. The total capacitance of the varactor bank is tunable from 146 fF to 430 fF in eight states and is suitable for X- or Ku-band operation. The design can be easily scaled to Ka-band frequencies. View full abstract»

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  • Fully integrated electrothermal multidomain modeling of RF MEMS switches

    Publication Year: 2003 , Page(s): 364 - 366
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (265 KB) |  | HTML iconHTML  

    RF MEMS switches have demonstrated excellent performance. However, before such switches can be fully implemented, they must demonstrate high reliability and robust power-handling capability. Numerical simulation is a vital part of design to meet these goals. This paper demonstrates a fully integrated electrothermal model of an RF MEMS switch which solves for RF current and switch temperature. The results show that the beam temperature increases with either higher input power or increased frequency. The simulation data are used to predict switch failure due to temperature-related creep and self pull-in over a wide range of operating frequency (0.1-40 GHz) and power input (0-10 W). Self pull-in is found to be the dominant failure mechanism for an example geometry. View full abstract»

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  • Noncontact measurement of charge induced voltage shift in capacitive MEM-switches

    Publication Year: 2003 , Page(s): 367 - 369
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (269 KB) |  | HTML iconHTML  

    The use of a modulated microwave signal to directly measure the voltage shift induced by charge in the dielectric layer of a capacitive microelectromechanical (MEM) switch is presented. This method does not require the metal bridge to contact the dielectric layer and is thus much less intrusive than previously reported measurements. The technique is a useful tool for understanding charge build up and dissipation in capacitive MEM switches. View full abstract»

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  • A microwave Doherty amplifier employing envelope tracking technique for high efficiency and linearity

    Publication Year: 2003 , Page(s): 370 - 372
    Cited by:  Papers (42)  |  Patents (53)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    In this letter, we demonstrate a microwave Doherty amplifier employing an input signal envelope tracking technique. In the amplifier, the gate bias of the peaking amplifier is controlled according to the magnitude of the envelope. A 2.14-GHz Doherty amplifier is implemented using 4-W PEP LDMOSFETs, and an adaptive controlled gate bias circuit is constructed and the control shape is optimized experimentally. The performance of the microwave Doherty amplifier is compared with that of a class AB amplifier using one-tone, two-tone, and forward-link wideband code-division multiple access (WCDMA) signals. For a forward-link WCDMA signal, the measured power added efficiency (PAE) of the microwave Doherty amplifier is 39.4% at -30 dBc adjacent channel leakage ratio (ACLR), while that of the comparable class AB amplifier is 24.2% at the same ACLR level. View full abstract»

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  • Silicon micromachined EBG resonator and two-pole filter with improved performance characteristics

    Publication Year: 2003 , Page(s): 373 - 375
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (587 KB) |  | HTML iconHTML  

    A novel micromachined resonator at 45 GHz based on a defect in a periodic electromagnetic bandgap structure (EBG) and a two-pole Tchebyshev filter with 1.4% 0.15 dB equiripple bandwidth and 2.3 dB loss employing this resonator are presented in this letter. The periodic bandgap structure is realized on a 400 μm thick high-resistivity silicon wafer using deep reactive ion etching techniques. The resonator and filter can be accessed via coplanar waveguide feeds. View full abstract»

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  • Scaled model measurement of the embedding impedance of a 660-GHz waveguide SIS mixer with a 3-standard deembedding method

    Publication Year: 2003 , Page(s): 376 - 378
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (307 KB) |  | HTML iconHTML  

    In this paper, the embedding impedance of a 660-GHz superconductor-insulator-superconductor (SIS) mixer is investigated using a 100-times scaled-model with a new 3-standard deembedding technique. The mixer embedding impedance is extracted from the reflection coefficients measured at the waveguide port of the mixer for three different terminations at the SIS junction's feed point. The three standards chosen are open-circuit, short-circuit and resistive load. Measured results are compared with those simulated by a high-frequency structure simulator (HFSS). View full abstract»

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  • Microwave indirect holographic imaging using an adaptation of optical techniques

    Publication Year: 2003 , Page(s): 379 - 381
    Cited by:  Papers (6)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    Indirect holography provides a quick and inexpensive three-dimensional (3-D) imaging technique at optical frequencies which has not been directly adapted to microwave imaging. This letter describes a technique whereby a radiated offset reference plane wave can be electronically synthesized allowing this technique to be used at microwave frequencies. In this letter, this technique has been applied to the problem of determining antenna radiation patterns and reconstructing complex near fields. Early experimental results compare favorably with results taken using traditional methods. View full abstract»

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  • A two-section dual-band Chebyshev impedance transformer

    Publication Year: 2003 , Page(s): 382 - 384
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (349 KB) |  | HTML iconHTML  

    We derive a two-section dual-band impedance transformer that matches a resistive load at two arbitrary frequencies. The transformer is equivalent to a two-section Chebyshev transformer whose parameters have been adjusted to achieve reflectionless notches at the two desired frequencies. View full abstract»

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  • A reduced-size dual-mode bandpass filter with capacitively loaded open-loop arms

    Publication Year: 2003 , Page(s): 385 - 387
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (441 KB) |  | HTML iconHTML  

    A novel type of dual-mode microstrip bandpass filter using degenerate modes of a dual-mode microstrip square loop resonator with capacitively loaded open-loop arms is proposed. Such a dual-mode bandpass filter with a 0.75% bandwidth at the center frequency of 1.603 GHz is designed and fabricated to demonstrate the design of reduced-size microstrip filters. It is shown that the proposed filter has a size reduction of about 59% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop and ring resonator filter. View full abstract»

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  • A Ka-band narrow bandpass filter using LTCC technology

    Publication Year: 2003 , Page(s): 388 - 389
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (262 KB) |  | HTML iconHTML  

    A Ka-band low-temperature co-fired ceramic (LTCC) narrow bandpass filter (BPF) is presented first. This BPF shows a very narrow 3 dB fractional bandwidth of 4.5% centered at 28.7 GHz. The advantages of multilayered LTCC technology such as high integration and vertical stacking capabilities were employed to design a three-dimensional interdigital end-coupled embedded microstrip narrow BPF. The difficulties in controlling the precise distance between two adjacent resonators in LTCC end-coupled BPF were overcome by locating the resonators on different layers. The measured insertion loss is 3 dB at 28.7 GHz. View full abstract»

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  • An efficient PEEC algorithm for modeling of LTCC RF circuits with finite metal strip thickness

    Publication Year: 2003 , Page(s): 390 - 392
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (422 KB) |  | HTML iconHTML  

    In this letter, a simple but effective method is introduced to facilitate the partial element equivalent circuit (PEEC) algorithm to model multilayered low-temperature co-fired ceramics (LTCC) embedded RF circuits with finite metal thickness. The method makes use of the quasistatic assumption that charges only reside on the surfaces of a conductor. In the calculation of the coefficient of potential matrix, one thick conductor plate is treated as two inter-connected zero-thickness plates. Recombining the two plates analytically can correctly account for the increase of plate-to-plate capacitance without adding extra elements to the resultant equivalent circuit model. Experimental results have verified the validation of the proposed method. View full abstract»

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  • Dual electromagnetic bandgap CPW structures for filter applications

    Publication Year: 2003 , Page(s): 393 - 395
    Cited by:  Papers (15)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (342 KB) |  | HTML iconHTML  

    A novel coplanar waveguide (CPW) low pass filter based on electromagnetic bandgaps (EBG) with double periodicity has been designed and fabricated. The device consists on a CPW with T-shaped loading capacitances at periodic positions and slot width modulation. By properly choosing the ratio between the two periods of the structure, a huge band gap (more than five times the bandwidth) is obtained through the suppression of spurious frequencies. The fabricated prototypes also exhibit very sharp cutoff, very low insertion loss in the passband and slow wave effect. View full abstract»

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  • Efficient analysis of waveguide components using a hybrid PEE-FDFD algorithm

    Publication Year: 2003 , Page(s): 396 - 398
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    The partial eigenfunction expansion (PEE) method combined with the classical finite difference frequency domain (FDFD) algorithm is proposed to accelerate frequency domain analysis of waveguide components. Examples are shown validating the method both for eigenvalue and deterministic problems. View full abstract»

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  • Time domain Green's functions for lossy and dispersive multilayered media

    Publication Year: 2003 , Page(s): 399 - 401
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (374 KB)  

    We have introduced a fast method of calculating the time domain Green's functions for multilayered media. In this paper, we demonstrate the use of this method to compute the scalar potential Green's function for a multilayer lossy dispersive medium on a PEC ground. The strength of the method lies in obtaining the Green's function for many source-to-field distances /spl rho/ and time instances t simultaneously. It only takes 6 min 28 s to compute 100/spl times/336=33 600 space time Green's function points in Matlab on a Pentium III 867 MHz processor with 1 GB of RAM for a multilayered lossy dispersive medium. View full abstract»

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  • Z-transform implementation of the perfectly matched layer for truncating FDTD domains

    Publication Year: 2003 , Page(s): 402 - 404
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (322 KB) |  | HTML iconHTML  

    A simple algorithm for implementing the perfectly matched layer (PML) is presented for truncating finite difference time domain (FDTD) computational domains. The algorithm is based on incorporating the Z-transform method into the PML FDTD implementation. The main advantage of the algorithm is its simplicity as it allows direct FDTD implementation of Maxwell's equations in the PML region. In addition, the formulations are independent of the material properties of the FDTD computational domain. Numerical examples are included to demonstrate the effectiveness of these formulations. View full abstract»

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  • A study of the numerical dispersion relation for the 2-D ADI-FDTD method

    Publication Year: 2003 , Page(s): 405 - 407
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (306 KB)  

    This letter presents a numerical dispersion relation for the two-dimensional (2-D) finite-difference time-domain method based on the alternating-direction implicit time-marching scheme (2-D ADI-FDTD). The proposed analytical relation for 2-D ADI-FDTD is compared with those relations in the previous works. Through numerical tests, the dispersion equation of this work was shown as correct one for 2-D ADI-FDTD. View full abstract»

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  • An adjoint variable method for frequency domain TLM problems with conducting boundaries

    Publication Year: 2003 , Page(s): 408 - 410
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB)  

    We propose a novel adjoint variable approach to design sensitivity analysis with the frequency domain transmission line modeling (FDTLM) method. An enlarged system matrix is constructed that includes the perturbed metal sections of the structure. The adjoint system of equations is then formed and solved. The derivatives of the responses with respect to all designable parameters are estimated using two analyses of the original and the adjoint systems. Second-order terms are included by approximating the values of the incident voltage waveforms in the perturbed areas. Our novel technique is illustrated through a number of examples. View full abstract»

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  • A new twisted differential line structure on high-speed printed circuit boards to enhance immunity to crosstalk and external noise

    Publication Year: 2003 , Page(s): 411 - 413
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (485 KB)  

    Differential signaling has become a popular choice for high-speed interconnection schemes on Printed Circuit Boards (PCBs), offering superior immunity to external noise. However, conventional differential transmission lines on PCBs have problems, such as crosstalk and radiated emission. To overcome these, we propose a Twisted Differential Line (TDL) structure on a multilayer PCB. Its improved immunity to crosstalk noise and the reduced radiated emission has been successfully demonstrated by measurement. The proposed structure is proven to transmit 3 Gbps digital signals with a clear eye-pattern. Furthermore, it is subject to much less crosstalk noise and achieves a 13 dB suppression of radiated emission. View full abstract»

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  • Investigation on the characteristics of the envelope FDTD based on the alternating direction implicit scheme

    Publication Year: 2003 , Page(s): 414 - 416
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB) |  | HTML iconHTML  

    This letter presents numerical characteristics of recently developed the envelope FDTD based on the alternating direction implicit scheme (envelope ADI-FDTD). Through numerical simulations, it is shown that the envelope ADI-FDTD is unconditionally stable and we can get better dispersion accuracy than the traditional ADI-FDTD by analyzing the envelope of the signal. This fact gives the opportunity to extend the temporal step size to the Nyquist limit in certain cases. Numerical results show that the envelope ADI-FDTD can be used as an efficient electromagnetic analysis tool especially in the single frequency or band limited systems. View full abstract»

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  • Enhancement of locking range through reactive loading on the feedback path

    Publication Year: 2003 , Page(s): 417 - 419
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    Coupled oscillator systems require oscillators with properties that heretofore have not been addressed in oscillator design. Specifically, one needs to achieve wide locking bandwidth - the counterpart to low Q if the oscillator is based on a resonant circuit. This letter introduces an approach to design of wide locking bandwidth by dealing with oscillator design in a feedback format. The specific realization reported here employs a MMIC amplifier with transmission line feedback external to the MMIC. Reactive loads that are weakly coupled to the transmission line allow one to achieve wide locking bandwidth. Results for an implementation at K/sub /spl alpha// band are provided. View full abstract»

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  • A low-power highly linear cascoded multiple-gated transistor CMOS RF amplifier with 10 dB IP3 improvement (Revised)

    Publication Year: 2003 , Page(s): 420 - 422
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (301 KB)  

    A low-power highly linear CMOS RF amplifier circuit composed of a Multiple-Gated common-source FET TRansistor (MGTR) in cascode configuration is reported. In an MGTR amplifier, linearity is improved by using transconductance linearization which can be achieved by canceling the negative peak value of g/sub m/" of the main transistor with the positive one in the auxiliary transistor having a different size and gate drive combined in parallel. This enhancement, however, is limited by the distortion originated from the combined influence of g/sub m/' and harmonic feedback, which can greatly be reduced by the cascoding MGTR output. IP3 improvement as large as 10 dB has been obtained from an experimental RF amplifier designed at 900 MHz and fabricated using 0.35 μm BiCMOS technology using only CMOS at a similar power consumption and gain as those obtainable from conventional cascode single gate transistor amplifiers. View full abstract»

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Aims & Scope

The IEEE Microwave and Wireless Components Letters (MWCL) publishes three page papers that focus on microwave theory, techniques and applications as they relate to components, devices, circuits, biological effects, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals.

Full Aims & Scope