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Microwave and Wireless Components Letters, IEEE

Issue 9 • Date Sept. 2002

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Displaying Results 1 - 14 of 14
  • A 2-bit RF MEMS phase shifter in a thick-film BGA ceramic package

    Page(s): 321 - 323
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (190 KB) |  | HTML iconHTML  

    The development of a thick-film hermetic BGA package for a radio-frequency (RF) microelectromechanical systems (MEMS) 2-bit phase shifter is presented. The measured packaged MEMS phase shifter average in-band insertion loss was 1.14 dB with an average return loss of 15.9 dB. The package transition insertion loss was less than 0.1 dB per transition with excellent agreement between simulated and measured results. It was also demonstrated that the RF MEMS phase shift performance could be improved to obtain a phase error of less than 3.3 degrees. The first reported measurements of the average rise and fall times associated with a MEMS circuit (in this case a 2-bit phase shifter) were 26 and 70 μs, respectively. The advent of packaged RF MEMS phase shifters will reduce the cost (both design and building) of future phase arrays. View full abstract»

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  • A compact V-band 2-bit reflection-type MEMS phase shifter

    Page(s): 324 - 326
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (210 KB) |  | HTML iconHTML  

    Air-gap overlay CPW couplers and low-loss series metal-to-metal contact microelectromechanical system (MEMS) switches have been employed to reduce the loss of reflection-type MEMS phase shifters at V-band. Phase shift is obtained by changing the lengths of the open-ended stubs using series MEMS switches. A 2-bit [135] reflection-type MEMS phase shifter showed an average insertion loss of 4 dB with return loss better than 11.7 dB from 50 to 70 GHz. The chip is very compact with a chip size as small as 1.5 mm /spl times/ 2.1 mm. View full abstract»

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  • Performance of 1-10-GHz traveling wave amplifiers in 0.18-μm CMOS

    Page(s): 327 - 329
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (183 KB) |  | HTML iconHTML  

    The authors present two four-stage traveling-wave amplifiers (TWA) fabricated in a 0.18-μm CMOS process. A TWA with an internal drain bias network achieved a gain of 5 dB out to 10 GHz, and another TWA without an on-chip bias network achieved a gain of 8 dB out to 10 GHz. These are the highest frequency CMOS TWAs known to the authors. View full abstract»

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  • A spiral-shaped defected ground structure for coplanar waveguide

    Page(s): 330 - 332
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    The authors present a spiral-shaped defected ground structure for coplanar waveguides (DGSCPW), which can be used as a kind of periodic structure for a planar transmission line. The proposed spiral-DGSCPW adopts spiral-shaped defects on both ground planes of CPW. Due to the spiral-shaped defects, the equivalent shunt inductance and slow-wave effects increase more rapidly than the standard CPW or CPW lines combined with the conventional PBG. The modeling and analysis to extract the equivalent circuit, increased slow-wave factor, and simulated and measured performances are presented. View full abstract»

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  • Dispersion characteristics of substrate integrated rectangular waveguide

    Page(s): 333 - 335
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (191 KB)  

    Dispersion properties of the substrate integrated rectangular waveguide (SIRW) are rigorously obtained using the BI-RME method combined with the Floquet's theorem. Our analysis shows that the SIRW basically has the same guided-wave characteristics as the conventional rectangular waveguide. Empirical equations are derived from the calculated dispersion curves in order to estimate the cutoff frequency of the first two dominant modes of the SIRW To validate the analysis results, an SIRW guide was designed and measured. Very good agreements between the experimental and theoretical results were obtained. View full abstract»

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  • A new approach to amplifier linearization by the generalized baseband signal injection method

    Page(s): 336 - 338
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (195 KB) |  | HTML iconHTML  

    The authors present a new technique for the reduction of third-order intermodulation distortion (IMD) in microwave amplifiers. A baseband predistortion signal is injected into a diode circuitry and the main amplifier to mix with the fundamental to generate a canceling signal for the suppression of the inherent IMD component. The proposed method can achieve higher linearity performance, in comparison to the conventional difference-frequency approach, and unlike many other techniques, no RF circuitry, such as variable gain amplifiers and phase-shifters, is needed other than baseband amplifiers. Both two-tone and vector signal measurement results are included. View full abstract»

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  • Equivalent-voltage approach for modeling low-frequency dispersive effects in microwave FETs

    Page(s): 339 - 341
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (201 KB) |  | HTML iconHTML  

    In this paper, a simple and efficient approach for the modeling of low-frequency dispersive phenomena in FETs is proposed. The method is based on the definition of a virtual, nondispersive associated device controlled by equivalent port voltages and it is justified on the basis of a physically-consistent, charge-controlled description of the device. Dispersive effects in FETs are accounted for by means of an intuitive circuit solution in the framework of any existing nonlinear dynamic model. The new equivalent-voltage model is identified on the basis of conventional measurements carried out under static and small signal dynamic operating conditions. Nonlinear experimental tests confirm the validity of the proposed approach. View full abstract»

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  • A physics-based GaAs PHEMT noise model for low drain bias operation using characteristic potential method

    Page(s): 342 - 344
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (207 KB) |  | HTML iconHTML  

    A new physics-based noise model of a GaAs PHEMT is developed using the characteristic potential method (CPM). The model calculates the intrinsic noise current sources using CPM. Combined with the extrinsic noise parameters extracted from the measured S-parameters, the model reproduces four noise parameters of the device accurately under low drain bias voltages without using any fitting parameters. The model is verified with a 0.2-μm GaAs PHEMT and shows excellent agreement with the measurements for all the noise parameters up to a drain voltage of 1 V Also, the proposed method allows the simulation of the microscopic noise distribution and thus allows one to obtain a physical understanding of noise mechanisms inside the device. View full abstract»

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  • Design of multiband microstrip antennas using a genetic algorithm

    Page(s): 345 - 347
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (223 KB) |  | HTML iconHTML  

    A genetic algorithm (GA) is used to design patch shapes of microstrip antennas for multiband operations. For dual-band operation, the optimized patches show that arbitrary frequency spacing ranging from 1:1.1 to 1:2 can be achieved. Tri-band and quad-band microstrip shapes are also generated and the resulting designs show good operations at the designated frequencies. All results were verified by laboratory measurements on an FR-4 substrate. View full abstract»

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  • Adaptive antenna receiver module for WLAN at C-band with low-power consumption

    Page(s): 348 - 350
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (219 KB) |  | HTML iconHTML  

    A low-power consuming adaptive antenna receiver module at C-band for 802.11a and HIPERLAN is presented. The highly integrated GaAs microwave monolithic integrated circuit consists of low noise amplifiers, calibration switches and a vector modulator with 360/spl deg/ phase control and over 15 dB gain control. At 5.2 GHz, the module has a maximum gain of 12.5 dB, a noise figure of 2.7 dB, and a 1 dB output compression point of -7 dBm. The module draws only 2.3 mA up to 3.5 mA from a 2.7 V supply. Chip size is 1.9 mm /spl times/ 1.6 mm. View full abstract»

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  • Comments on "Ill conditioning in self-heating FET models" [and reply]

    Page(s): 351 - 352
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (185 KB)  

    A recent letter by S.A. Maas (see ibid., vol.12, no.3, p.88-9, March 2002) reported ill conditioning in nonlinear circuit simulators caused by the introduction of self-heating effects into FET models. This is true for circumstances outlined in that work but is a consequence of using an incomplete thermal model. This letter points out that an account for both thermal potential and mobility variation with temperature will eliminate the problem. View full abstract»

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  • Author's reply

    Page(s): 352
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    Prof. Parker makes the point that a properly designed model should not predict thermal instability or have multiple solutions in a device that is thermally stable, and, if it does, the model is not doing its job. The issue addressed in the original letter [ibid., vol. 12, pp. 88??89, Mar. 2002] goes a bit beyond this, however. Since self-heating models are inherently nonlinear, and many model designers seem unable to avoid equating complexity with accuracy, it is almost inevitable that multiple solutions can occur, under some conditions. A harmonic-balance analysis searches over a wide range of its independent variables (usually voltage components) to find a solution, so multiple solutions, even at unrealistic temperatures, are likely to be discovered. Models are frequently formulated to work in the expected range of temperatures, and often are not robust outside of that range. Another concern is the existence of indistinct solutions, which can lead to convergence failure in harmonic-balance analysis. The example presented by Prof. Parker can be modified to make it ill conditioned. Details are given. View full abstract»

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  • Comments on "Improvement of broadband feedforward amplifier using photonic bandgap"

    Page(s): 352 - 353
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (159 KB)  

    A number of technical facts were either claimed or implied in the letter by J. Yoon and C. Seo (see ibid., vol.11, no.11, p.450-2, Nov. 2001). Without clarification or supporting data, the claims presented could mislead the reader into drawing inaccurate conclusions regarding the performance increase of feed forward amplifiers due to the so-called photonic bandgap structure. View full abstract»

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  • Patent abstracts

    Page(s): 354 - 364
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    Freely Available from IEEE

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