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Microwave and Wireless Components Letters, IEEE

Issue 10 • Date Oct. 2009

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Displaying Results 1 - 25 of 27
  • Table of contents

    Page(s): C1 - C4
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  • IEEE Microwave and Wireless Components Letters publication information

    Page(s): C2
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  • Scattering Domain Passivity Verification and Enforcement of Delayed Rational Functions

    Page(s): 605 - 607
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (110 KB) |  | HTML iconHTML  

    This letter introduces new algorithms for passivity verification and compensation of macromodels constructed from delayed rational functions in the scattering domain. For passivity verification, a frequency-dependent generalized eigenvalue is formulated, which is used to accurately determine the regions of passivity violation. For passivity compensation, first order perturbation theory is used to iteratively perturb the residues of the system until passivity is achieved. Numerical results validating the proposed algorithms are presented. View full abstract»

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  • Parameterized S-Parameter Based Macromodeling With Guaranteed Passivity

    Page(s): 608 - 610
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (463 KB) |  | HTML iconHTML  

    This letter presents a novel parametric macromodeling technique for scattering input-output representations parameterized by design variables such as geometrical layout or substrate features. It provides accurate multivariate macromodels that are stable and passive by construction over the entire design space. Overall stability and passivity of the parametric macromodel are guaranteed by an efficient and reliable combination of rational identification and interpolation schemes based on a class of positive interpolation operators. View full abstract»

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  • A Three-Section Dual-Band Transformer for Frequency-Dependent Complex Load Impedance

    Page(s): 611 - 613
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (149 KB) |  | HTML iconHTML  

    In this letter, we propose a practical three-section dual-band transformer, which can terminate frequency-dependent complex load impedance at two arbitrary bands simultaneously. Analytical equations are derived to achieve the exact closed-form solutions. Numerical examples are examined to verify the validity. This three-section transformer can be utilized to match the complex load impedance with unequal values at two different frequencies, such as microwave amplifiers based on transistors, mixers, various kinds of antennas, and so forth. View full abstract»

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  • Engineered Passive Nonlinearities for Broadband Passive Intermodulation Distortion Mitigation

    Page(s): 614 - 616
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (223 KB) |  | HTML iconHTML  

    By adding controlled thicknesses of nickel and gold plating to the conductors of a coaxial transmission line, the magnitude of passive intermodulation produced by the transmission line can be controlled with precision. Theoretical predictions of distortion magnitude as a function of plating thicknesses are presented, along with an experimental validation. These adjustable-magnitude passive intermodulation sources are used to give a fourfold improvement in the bandwidth of techniques presented previously, demonstrating that cancellation can for the first time be achieved in bandwidths needed for cellular systems. View full abstract»

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  • Dual-Band, Unequal Length Branch-Line Coupler With Center-Tapped Stubs

    Page(s): 617 - 619
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    A new dual-band branch-line coupler scheme is proposed based on the unequal length branch-line coupler structure and the center-tapped stub lines. The unequal length structure reduces the size of the dual-band branch-line coupler using center tapped stubs. Also, it offers the possibility of the stubless dual-band operation for some special cases, and the same phase relation can be obtained between the two output signals at the two frequency bands. View full abstract»

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  • Suspended Spiral Inductor and Band-Pass Filter on Thick Anodized Aluminum Oxide

    Page(s): 620 - 622
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1095 KB) |  | HTML iconHTML  

    We make suspended inductors and 2.45 GHz BPFs on the selectively anodized aluminum. The thick anodized alumina is used as the supporting dielectric and it is easily removed by using chemical wet-etching. The thickness of anodized alumina is 80 mum and the depth of the total air-cavity is 200 mum. The fabricated inductor over an air cavity has a 25% greater Q factor and 21% higher inductance at 2 GHz compared to an inductor on anodized aluminum. The 2.45 GHz BPF adjusting the suspended inductors has 2.8 dB of insertion loss with a narrow bandwidth. View full abstract»

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  • Air-Cavity Transmission Lines on Anodized Aluminum for High-Performance RF Modules

    Page(s): 623 - 625
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    In this study, we form air-cavity transmission lines on anodized aluminum substrates. The fabricated transmission lines are microstrip, grounded CPW, and microshield structures. Thick anodized alumina is used as the post of the suspending structures, and it is realized very easily using selective chemical wet-etching. The insertion losses of the fabricated transmission lines on the anodized aluminum are within a range of 0.2-0.26 dB/mm, and they improve greatly after realizing air-cavity structures to 0.043-0.076 dB/mm at 40 GHz. View full abstract»

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  • A Dual-Band Combline Bandpass Filter Loaded by Lumped Series Resonators

    Page(s): 626 - 628
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (383 KB) |  | HTML iconHTML  

    This letter presents a dual-band combline bandpass filter (BPF) loaded by lumped series resonators. The proposed filter configuration can easily generate two desired passbands by controlling the resonant frequencies of the comblines as well as the series resonators. Furthermore, the skirt frequency characteristics between the two passbands are improved by transmission zeros introduced by source-load coupling via a lumped element capacitor. Two-pole dual-BPF with center frequencies of 1.2 and 1.54 GHz is designed and the measured results agree well with simulated results. View full abstract»

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  • A Novel Low-Pass Filter With an Embedded Band-Stop Structure for Improved Stop-Band Characteristics

    Page(s): 629 - 631
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (310 KB) |  | HTML iconHTML  

    This letter presents a novel design of a microstrip low- pass filter (LPF) with an embedded band-stop structure, which is constructed from a simple two transmission line band-stop filter. The band-stop structure is ingeniously embedded into a classical step-impedance microstrip LPF. The stop-band of the proposed LPF is more than two times broader than the original design, while its cut-off frequency remains at 1.8 GHz. The embedded structure does not increase the physical dimension of the LPF, but improves the performance significantly. Measured results agree with simuAcircnot lation well, and validate the dual-frequency design method. View full abstract»

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  • A Differential-Mode Wideband Bandpass Filter on Microstrip Line for UWB Application

    Page(s): 632 - 634
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (197 KB) |  | HTML iconHTML  

    A differential-mode wideband bandpass filter (BPF) on microstrip line is proposed with good common-mode suppression. A four port two stage branch-line differential-mode BPF is first designed. Then, open circuited stubs are attached to the middle of two of the vertical branches. As such, its two-port bisection becomes a bandpass or bandstop filtering topology under differental- or common-mode excitations, respectively. The lengths and widths of these stubs can be properly adjusted to produce a highly attenuated and widened stopband under the common-mode operation. Finally, a wideband differential-mode BPF is designed and fabricated. The predicted and measured performances are in good agreement with each other, showing good common-mode suppression with an insertion loss higher than 20 dB over the differential-mode passband with a fractional bandwidth of 65%. View full abstract»

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  • A Superconducting Microstrip Ultra-Wideband (UWB) Bandpass Filter at VHF-Band

    Page(s): 635 - 637
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (259 KB) |  | HTML iconHTML  

    A compact superconducting ultra-wideband filter with a passband from 125 to 260 MHz is demonstrated. The filter consists of ten shunt short-circuited stubs separated by connecting lines. The short-circuited stubs are grounded via a grounding strip that is attached to the box wall by a number of SiAl bonding wires. The filter is realized on two 2 in YBCO/LaAlO3 substrates, which are connected by two bonding wires. The measured results demonstrate an insertion loss of less than 0.08 dB and a return loss of better than 21 dB without tuning. Furthermore, the experimental results of the filter are in good agreement with the simulated ones. View full abstract»

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  • Passive Millimeter-Wave Microscopy

    Page(s): 638 - 640
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB) |  | HTML iconHTML  

    A new type of millimeter-wave imaging technique, passive millimeter-wave microscopy is proposed and demonstrated. Passive millimeter-wave imaging techniques when combined with scanning near-field microscopy enable direct observation of millimeter-wave signals thermally emitted from the viewed object with a spatial resolution below the diffraction limit. Details of our passive microscope system operating at Ka-band frequencies are explained. Millimeter-wave images obtained with the system are presented to demonstrate the feasibility of this new imaging technique. View full abstract»

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  • Waveguide Probes Using Single Negative Media

    Page(s): 641 - 643
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (342 KB) |  | HTML iconHTML  

    In this work, we show that by using single negative (SNG) media, the sensitivity of open-ended near-field waveguide probes can be enhanced. The enhancement is due to the evanescent wave amplification property of SNG media. As a demonstration of the efficacy of the proposed SNG-enhanced probe, we present a numerical study of the case of detecting precursor pitting in aluminum plates. We show that the SNG-enhanced probe achieves 35 times increase in the phase shift due to the presence of the target in comparison to the case of a classical probe. We show that there is an optimum SNG media thickness and an optimum standoff distance that maximize the sensitivity. View full abstract»

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  • A 60 GHz Six-Port Distance Measurement System With Sub-Millimeter Accuracy

    Page(s): 644 - 646
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    A new compact six-port millimeter-wave distance measurement system is presented. The radar operates at the single frequency of 60 GHz and makes use of both the magnitude and phase of the measured free-space reflection coefficient to overcome the ambiguity of phase. The principle of operation, the system and experimental results are described in this letter. View full abstract»

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  • Broadband InGaAs PIN Traveling-Wave Switch Using a BCB-Based Thin-Film Microstrip Line Structure

    Page(s): 647 - 649
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (217 KB) |  | HTML iconHTML  

    This letter describes the design and fabrication of a broadband InGaAs PIN traveling wave switch. A new thin-film microstrip line structure integrated with InGaAs PIN diodes has been used to enhance the switch performance at higher frequencies. The developed InGaAs PIN switch has an insertion loss of less than 3.2 dB and an isolation of greater than 40 dB in a broadband frequency range from 25 to 95 GHz. The BCB-based multi-layer technology effectively reduces the chip size of the fabricated SPDT MMIC switch to 1.05 times 0.58 mm2. To our knowledge, this is the first InGaAs PIN traveling-wave switch demonstrated up to 95 GHz. View full abstract»

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  • A Low-Noise WLAN Mixer Using Switched Biasing Technique

    Page(s): 650 - 652
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    A low-noise CMOS down-conversion mixer for WLAN applications is presented in this letter. The proposed mixer is based on the conventional Gilbert-type topology with switched biasing technique for a current source instead of static biasing, which lowers noise over a wide range of frequencies. Moreover, a dc level shifter is used for the symmetric switching operation in tail current transistors. A current bleeding technique is adopted to reduce the noise caused by the LO switching operation. The proposed mixer was fabricated using a 0.18 mum 1P6M CMOS process. Measurement results include a conversion gain of 7.5 dB, an IIP3 of -5 dBm, and noise figures of 10.9 dB at 1 MHz and 7.6 dB at 100 MHz. The mixer core consumes a current of 4.5 mA from a supply voltage of 1.8 V. The chip size, including pads for measurements, is 0.88 times 0.88 mm2. View full abstract»

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  • A Wide Tuning Range Voltage Controlled Oscillator Using Common-Base Configuration and Inductive Feedback

    Page(s): 653 - 655
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    Usually the tuning range of voltage controlled oscillator (VCO) is much narrower than the possible resonant frequency range of the tank at different tuning voltages. In this letter we analyze the traditional common-base type VCO, give a simple but useful insight about the mechanism behind the topology, and verified the conclusions with a 2 mum heterojunction bipolar transistor (HBT) VCO. The results show that with the CB configuration, proper feedback inductor and wide tuning range varactor, the tuning range can be almost the same as the resonant frequency range of the tank at different tuning voltages. A wideband voltage controlled oscillator using a commercial 2 mum HBT technology is designed, fabricated and measured. The varactor with wide range of capacitance is used to achieve 53.33% measured tuning range from 9.46 to 16.34 GHz. The measured phase noise at 1 MHz offset is between -90 and -102 dBc/Hz. The total chip size is 1 mm2 including all testing pads, while the core area is 0.64 mm2. The VCO is suitable for wideband application such as in measurement equipment or astronomical exploring telescopes. View full abstract»

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  • An E-TSPC Divide-by-2 Circuit With Forward Body Biasing in 0.25 \mu m CMOS

    Page(s): 656 - 658
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (589 KB) |  | HTML iconHTML  

    A forward body biasing (FBB) technique is employed by an extended true-single-phase-clock (E-TSPC) divide-by-2 circuit in 0.25 mu m CMOS for an efficient on-chip control of power and speed. By applying the forward body bias voltage of 0.4 V, the maximum operating frequency is improved by 78% while the current dissipation is increased only by 21%. As a result, the divider figure-of-merit is improved by 46%. The phase noise however is not significantly affected by the forward body biasing. We believe that the FBB technique can be an efficient means for on-chip scaling of speed and power in E-TSPC RF frequency divider circuits. View full abstract»

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  • A 10 GHz Phase-Locked Loop With a Compact Low-Pass Filter in 0.18 \mu m CMOS

    Page(s): 659 - 661
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (541 KB) |  | HTML iconHTML  

    In this letter, a multi-gigahertz phase-locked loop (PLL) with a compact low-pass filter is presented. By using a novel dual-path control in the PLL architecture, the capacitance in the loop filter can be effectively reduced for high-level integration while maintaining the required loop bandwidth. Consequently, the noise resulted from off-chip components is therefore eliminated, leading to lower timing jitter at the PLL output waveforms. In addition, the timing jitter is further suppressed due to the use of decomposed phase and frequency detection. Based on the proposed techniques, a 10 GHz PLL is implemented in 0.18 mum CMOS for demonstration. Consuming a dc power of 113 mW from a 1.8 V supply, the fabricated circuit exhibits a locking range from 10.1 to 11 GHz. At an output frequency of 10.3 GHz, the measured peak-to-peak and rms jitter are 3.78 and 0.44 ps, respectively. View full abstract»

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  • A 0.6 V Low-Power Wide-Range Delay-Locked Loop in 0.18 \mu m CMOS

    Page(s): 662 - 664
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (409 KB) |  | HTML iconHTML  

    In this letter, a delay-locked loop (DLL) suitable for low-power and low-voltage operations is presented. To overcome the performance limitations, such as a restricted locking range and elevated output jitters, a novel voltage-controlled delay cell and a phase/frequency detector with a start controller are employed in the proposed DLL. Using a standard 0.18 mum CMOS process, the fabricated circuit exhibits a locking range from 85 to 550 MHz. The measured peak-to-peak and rms jitters at 550 MHz are 25.6 and 3.8 ps, respectively. Operated at a supply voltage of 0.6 V, the power consumption of the DLL circuit varies from 2.4 to 4.2 mW within the entire locking range. View full abstract»

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  • On the Continuity of High Efficiency Modes in Linear RF Power Amplifiers

    Page(s): 665 - 667
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (338 KB) |  | HTML iconHTML  

    A novel formulation for the voltage waveforms in high efficiency linear power amplifiers is described. This formulation demonstrates that a constant optimum efficiency and output power can be obtained over a continuum of solutions by utilizing appropriate harmonic reactive impedance terminations. A specific example is confirmed experimentally. This new formulation has some important implications for the possibility of realizing broadband >10% high efficiency linear RF power amplifiers. View full abstract»

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  • A New Wideband Distributed Doherty Amplifier for WCDMA Repeater Applications

    Page(s): 668 - 670
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    A new wideband distributed Doherty amplifier (WDDA) for wideband code division multiple access (WCDMA) repeater applications is reported. The distributed structure provides wideband performance while not needing an N-way splitter and combiner. The two-stage Doherty amplifiers achieve high gain and high efficiency. Also, the linearity of the WDDA is improved by the post-distortion using gate bias optimization of the Doherty amplifiers. For verification, the proposed WDDA is implemented using GaN HEMTs and tested with a one-carrier WCDMA signal at 2.14 GHz. From the measured results at an average output power of 36 dBm (10 dB back-off power), the WDDA shows an adjacent channel leakage ratio (ACLR) of - 45 dBc at plusmn 5 MHz offset with a total gain over 24 dB and a total power-added efficiency over 15% over a 160 MHz bandwidth. View full abstract»

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  • A Novel Linearization Method of CMOS Drive Amplifier Using IMD Canceller

    Page(s): 671 - 673
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB) |  | HTML iconHTML  

    A novel linearization method for CMOS drive amplifier using intermodulation distortion (IMD) canceller is presented. The IMD cancellation method is composed of a cascode main amplifier and a common-source IMD canceller. The additional common-source amplifier generates IMD3 signals with 180deg phase difference against the IMD3 of the cascode main amplifier. The linear drive amplifier is designed and fabricated by CMOS 0.18 mum process. The output IP3 of +13 dBm is achieved with the power gain of +11.6 dB, the output P1 dB of + 5.5 dBm, and the power-added efficiency of 21%. 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.

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