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Microwave Theory and Techniques, IEEE Transactions on

Issue 2 • Date Feb. 2007

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  • Table of contents

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

    Publication Year: 2007 , Page(s): C2
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  • Guest Editorial [intro. to the special issue on applications of ferroelectrics in microwave technology]

    Publication Year: 2007 , Page(s): 353
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  • Improving Linearity of Ferroelectric-Based Microwave Tunable Circuits

    Publication Year: 2007 , Page(s): 354 - 360
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1588 KB) |  | HTML iconHTML  

    A device architecture for improving the linearity of barium-strontium-titanate (BST) capacitors is proposed, analyzed, and experimentally demonstrated. The basic concept is to reduce the RF swing across the ferroelectric varactors by connecting multiple capacitors in series. With proper biasing networks, the overall device preserves its tunability. In this paper, the proposed architecture is analyzed to derive the equations that relate its quality factor and tuning speed to the design parameters. Parallel-plate BST capacitors are fabricated based on the architecture. Various measurements are performed to demonstrate the efficacy of the technique. The third-order intercept point at input (IIP3) is found to be improved by 16 dB. The hot-tuning test shows that the tunability is maintained for up to 20-V peak-to-peak swing. BST capacitors utilizing the proposed technique are used in a phase-shifter design. The 2.4-GHz phase shifter exhibits high IIP3 greater than 40 dBm View full abstract»

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  • A Low-Noise K-Band VCO Based on Room-Temperature Ferroelectric Varactors

    Publication Year: 2007 , Page(s): 361 - 369
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1550 KB) |  | HTML iconHTML  

    This paper reports a K-band voltage-controlled oscillator based on room-temperature ferroelectric varactors. The circuit is realized as a hybrid module where flip-chip transistors are mounted on a silicon substrate with integrated ferroelectric varactors and passive circuitry. The size of the module is 4.7times2.2 mm2. The measured center frequency is 16.5 GHz with a linear tunability of 6.7% and an output power of 3 dBmplusmn1 dB over the tuning range. The measured phase noise at center frequency is -95 dBc/Hz at 100-kHz offset. Another version of the oscillator is measured operating at 19.6 GHz with a tunability of 3.3% and a phase noise of -102 dBc/Hz at 100-kHz offset View full abstract»

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  • A Ferroelectric-Capacitor-Based Tunable Matching Network for Quad-Band Cellular Power Amplifiers

    Publication Year: 2007 , Page(s): 370 - 375
    Cited by:  Papers (14)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (714 KB) |  | HTML iconHTML  

    A tunable matching network (TMN) based on ferroelectric capacitors for cellular power-amplifier applications was designed, fabricated, and tested. When the matching network is operated for GSM850/900 frequency bands, the input impedance varied from 3.44-j1.87 to 3.55-j0.02 Omega with a power gain variation of -1.35 to -1.62 dB. When the circuit is operated for digital communication system/personal communication system/wideband code division multiple access frequency bands, the input impedance varied from 4.28-j0.06 to 4.31+j0.97 Omega with a power gain variation of -2.05 to -1.79 dB. The nonlinearity of the TMN was also characterized on an on-wafer load-pull system using a 1.95-GHz test signal with CDMA2000 and high-speed downlink packet access modulation strings View full abstract»

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  • Frequency and Bandwidth Agile Millimeter-Wave Filter Using Ferroelectric Capacitors and MEMS Cantilevers

    Publication Year: 2007 , Page(s): 376 - 382
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1038 KB) |  | HTML iconHTML  

    This paper demonstrates for the first time a tunable bandpass filter with simultaneous frequency and bandwidth control using a combination of ferroelectric barium-strontium-titanate capacitors and cantilever microelectromechanical systems (MEMS) switches. The center frequency of the filter is tuned in a continuous fashion from 30 to 35 GHz with insertion loss ranging from 10 to 2.7 dB. The fractional bandwidth of the filter can also be independently controlled by a tuning scheme that uses MEMS switches to vary the inter-resonator coupling. The two-pole filter prototypes resulted in fractional bandwidths of 9.6% (wideband configuration) and 4.8% (narrowband configuration) for a tuning ratio of approximately 2:1. The third-order filters resulted in bandwidths of 7.8% (wideband configuration) and 3.1% (narrowband configuration) for a passband tunable ratio of approximately 2.5:1 View full abstract»

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  • Modeling and Applications of Ferroelectric-Thick Film Devices With Resistive Electrodes for Linearity Improvement and Tuning-Voltage Reduction

    Publication Year: 2007 , Page(s): 383 - 390
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1418 KB) |  | HTML iconHTML  

    Low-cost planar high-Q ferroelectric-thick film varactors (Qap90) are realized and component architectures using resistive electrodes for dc bias are investigated. A basic model for planar capacitors with resistive electrodes in the gap is developed and verified by finite-difference time-domain simulations and measurements of interdigital capacitors with high-resistivity indium-tin-oxide bias electrodes in the gap. An optimized high-Q capacitor design based on a series connection of ferroelectric varactors with resistive bias decoupling is presented. The approach allows the increase of device linearity and the reduction of tuning voltages. Based on this technology, a continuously tunable high-power impedance-matching network for 1.875 GHz with tuning voltages below 60 V was developed, realized, and characterized by small- and large-signal measurements with up to 33-dBm input power. The device requires no external dc-block or RF decoupling and features separated RF and dc contacts. The output IP3 of up to 47.8 dBm verifies the excellent device linearity View full abstract»

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  • Frequency Tuning and Spurious Signal Generation at Microwave Frequencies in Ferroelectric SrTiO3 Thin-Film Transmission Lines

    Publication Year: 2007 , Page(s): 391 - 396
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    This paper evaluates the RF tuning and the microwave nonlinear response of SrTiO3 thin films by measuring the third harmonics and third-order intermodulation (IMD) products of several coplanar waveguide transmission lines fabricated directly on SrTiO3 thin-film samples. From these measurements, we obtained the distributed nonlinear capacitance per unit length as a function of RF bias voltage C(Vrf) using an accurate equivalent circuit to model the spurious signal generation. A unique value of C(Vrf) is used to describe the third-harmonic generation at frequencies 3f1 and 3f2, and the IMD products at frequencies 2f1+f2 and 2f2+f1, where f1 and f2 represent the fundamental frequencies of the two-tone excitation signal. We compare C(Vrf) with the distributed nonlinear capacitance measured as a function of the dc-bias voltage C(Vdc) and obtain excellent agreement at 50 and 76 K. From these results, we conclude that full tunability can be achieved on nanosecond time scales, and that spurious signals generated in SrTiO3 ferroelectric transmission lines at microwave frequencies can be modeled based on dc-biased measurements View full abstract»

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  • Comparison of Techniques for Microwave Characterization of BST Thin Films

    Publication Year: 2007 , Page(s): 397 - 401
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (401 KB) |  | HTML iconHTML  

    Various techniques involving coplanar waveguide transmission lines, coplanar resonators, and interdigital capacitors, have been employed to characterize the dielectric properties of Ba0.05Sr0.95TiO3 thin films at cryogenic conditions. The devices were patterned from a high-temperature superconductor deposited on top of a single Ba0.05Sr0.95 TiO3 thin film. The measurements from these various techniques show a good agreement View full abstract»

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  • Modified Green's Function and Spectral-Domain Approach for Analyzing Anisotropic and Multidielectric Layer Coplanar Waveguide Ferroelectric Phase Shifters

    Publication Year: 2007 , Page(s): 402 - 409
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    Phase-shifter design based on ferroelectric materials technology has shown promising performance characteristics and the potential for achieving the long standing goal of realizing high performance, low-cost microwave phase shifters, and phased-array antennas. In this paper, we present a unifying spectral-domain approach and a newly derived Green's function that provide a "first principles" method for the design and analysis of ferroelectric material based coplanar waveguide phase shifters. The modified Green's function not only accounts for the finite thickness of the conductors, but also for the "current crowding" phenomena that results from using the very high dielectric constant ferroelectric film. Both isotropic and anisotropic effects were analyzed and the developed theoretical results were in excellent agreement with measured data. It is also shown that the multidielectric layer-based design of these phase shifters may provide nearly threefold increase in the figure-of-merit compared with the direct metallization case. A new biasing approach is proposed to achieve effective biasing of the ferroelectric layer and without excessive field concentration in the overlaying low dielectric layer. The formulation, procedure for the calculation of the current and charge distributions, and comparison between simulation and experimental results are described and presented in detail View full abstract»

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  • Geometry-Dependent Quality Factors in Ba0.5Sr0.5TiO3 Parallel-Plate Capacitors

    Publication Year: 2007 , Page(s): 410 - 417
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1976 KB) |  | HTML iconHTML  

    Quality factor variation with top electrode area in thin-film barium-strontium-titanate parallel-plate capacitors is discussed. At low frequencies, the geometry dependence is consistent with the presence of a parallel parasitic loss pathway enabled by conduction over the device mesa surface. At high frequencies, the variation in the quality factor with top electrode area is due to a geometry-independent series resistance View full abstract»

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  • Investigation of Ferroelectric Thick-Film Varactors for Microwave Phase Shifters

    Publication Year: 2007 , Page(s): 418 - 424
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1496 KB) |  | HTML iconHTML  

    This paper presents a novel cost-effective microwave phase-shifter technology using thick-film ferroelectric varactors as the tuning component. The devices are fabricated by conventional screen-printing techniques with silver/platinum as the conducting layers and Ba0.7 Sr0.3TiO3 as the tunable dielectric layer. The microwave performance of the ferroelectric varactors is optimized in terms of both material process parameters and the varactor gate area dimensions. S-parameter measurements on a tunable reflective circuit are used to evaluate the performance of the varactor at around 2 GHz. The varactor parameters such as RF capacitance, tunability, and the Q factor of the varactor are studied as a function of the gate dimension. At 100-V dc-biasing voltage, the BSTO varactor loaded tunable reflective circuit exhibits a differential phase shift of 70deg with a return loss of -1.2 dB. This is equal to a figure-of-merit value of 58deg/dB. Full analog reflection-type and all-pass network phase shifters are also implemented in order to explore the monolithic integration of phase control devices into the RF system based on low-cost ceramic thick-film technology View full abstract»

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  • Insertion Loss in Reflection-Type Microwave Phase Shifter Based on Ferroelectric Tunable Capacitor

    Publication Year: 2007 , Page(s): 425 - 429
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    A tunable capacitor based on a ferroelectric thin film grown on a dielectric substrate is a promising component for reconfigurable and tunable devices for numerous RF and microwave applications such as phase shifters, tunable filters, and tunable matching networks. The goal of this paper is characterization of the insertion loss in a reflection-type microwave phase shifter based on the ferroelectric tunable capacitor. The reflection-type phase shifter based on ferroelectric planar tunable capacitor was designed, manufactured, and tested. Its simulated and measured insertion loss and phase shift are compared. Two loss mechanisms in the phase shifter were distinguished: the loss in the tunable capacitor and the loss in the associated circuitry (metallization and substrate). The properly organized investigations of the dissipation of energy in metallization and dielectric substrate can result in a sufficient improvement of the quality of the devices. As a final result, one may anticipate that the figure-of-merit of a ferroelectric tunable or switchable phase shifter can reach 200 deg/dB View full abstract»

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  • Ferroelectric Phase Shifters at 20 and 30 GHz

    Publication Year: 2007 , Page(s): 430 - 437
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1452 KB) |  | HTML iconHTML  

    This paper presents continuously variable 20- and 30-GHz ferroelectric 360deg phase shifters. A lumped-element all-pass network topology is used for the phase-shifter designs. The phase shifters are fabricated using barium-strontium-titanate (BST) capacitors as the tuning element. The BST thin films are epitaxially grown on sapphire substrates using the combustion chemical vapor deposition process, exhibiting low loss and high tunability. The 20-GHz phase shifter has a dimension of 0.95times1.32times0.5 mm3; its maximum phase shift occurs at 21.7 GHz, where the insertion loss varies from 6.1 to 3.9 dB and the return loss is from 15.2 to 4.7 dB. Measured figure-of-merit is 54deg/dB using the highest insertion loss. The dimension of the 30-GHz phase shifter is 1times1.2times0.5 mm3 . Measured insertion loss and return loss vary from 7.0 to 4.3 dB and from 29 to 4.8 dB, respectively, at a center frequency of 32 GHz. The figure-of-merit is 51deg/dB. The dc bias required to tune the low-voltage phase shifters is 0-30 V. Typical third-order input intercept power (IIP3) of the phase shifters is greater than 30 dBm View full abstract»

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  • A 360° BST Phase Shifter With Moderate Bias Voltage at 30 GHz

    Publication Year: 2007 , Page(s): 438 - 444
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1518 KB) |  | HTML iconHTML  

    Paraelectric BaSrTiO3 films deposited by sol-gel have been investigated from 1 kHz to 40 GHz using coplanar waveguides, resonators, and inter-digitated capacitances. At room temperature and without bias, the dielectric constant epsivr is around 300 and the loss tangent is 5times10-2. Tunability is 40% for a 40-V bias voltage. Analog phase-shifter circuits were subsequently fabricated in order to obtain a 360deg phase shift in the Ka-band with a moderate bias voltage. The lowest bias value was 17 V at 40 GHz, whereas 40 V were necessary at 30 GHz. For the latter condition, the insertion loss was -6dB. The best figure-of-merit of the phase shifters with a loading factor of 1.4 was 27deg/dB. These results show an improvement in terms of voltage-controlled tunability View full abstract»

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  • IEEE Transactions on Microwave Theory and Techniques information for authors

    Publication Year: 2007 , Page(s): 445
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    Publication Year: 2007 , Page(s): 446
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    Publication Year: 2007 , Page(s): 447
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    Publication Year: 2007 , Page(s): 448
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  • IEEE Microwave Theory and Techniques Society Information

    Publication Year: 2007 , Page(s): C3
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    Publication Year: 2007 , Page(s): C4
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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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