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Microwave Theory and Techniques, IEEE Transactions on

Issue 1 • Date Jan. 2012

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  • Table of contents

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

    Page(s): C2
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  • Multi-Mode Coupling Wave Theory for Helically Corrugated Waveguide

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1035 KB) |  | HTML iconHTML  

    Helically corrugated waveguide has been used in various applications such as gyro-backward wave oscillators, gyro-traveling wave amplifier and microwave pulse compressor. A fast prediction of the dispersion characteristic of the operating eigenwave is very important when designing a helically corrugated waveguide. In this paper, multi-mode coupling wave equations were developed based on the perturbation method. This method was then used to analyze a five-fold helically corrugated waveguide used for X-band microwave compression. The calculated result from this analysis was found to be in excellent agreement with the results from numerical simulation using CST Microwave Studio and vector network analyzer measurements. View full abstract»

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  • Passivity Enforcement for Admittance Models of Distributed Networks Using an Inverse Eigenvalue Method

    Page(s): 8 - 20
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1446 KB) |  | HTML iconHTML  

    Most transient circuit simulators are based on admittance representations of the constituent circuit elements. It is therefore natural to use admittance parameter descriptions of linear networks, preferably in the form of rational transfer functions that can be directly implemented in the analysis. A problem arises when the measured or calculated frequency-domain response of a linear distributed network must be derived from data that has inherent error, is of limited bandwidth, or is not in the appropriate rational form. A reduced-order rational model that is causal, stable, and passive must be developed. Previous methods of deriving rational functions for the admittance parameters of a network do guarantee stability and causality, but passivity of the model must be assured through subsequent post-processing. Enforcing passivity requires modification of the state-space parameters of the model with consequent introduction of errors. This paper reports on a procedure to simultaneously achieve passivity, accuracy, causality, and stability in the development of an admittance macromodel described using a matrix of rational functions. An iterative inverse eigenvalue algorithm enforces passivity, and is applied by conjoining sets of eigenvalue and admittance constraints. These constraints form a monolithic projection matrix, which simultaneously addresses both passivity and accuracy of the model. View full abstract»

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  • Extended Passband Bandstop Filter Cascade With Continuous 0.85–6.6-GHz Coverage

    Page(s): 21 - 30
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    This paper presents a cascade of tunable bandstop filters with a wide spurious-free upper passband, which is completely spanned by the tuning range of the notch responses. A collection of resonators is shown to be able to provide bandstop filter responses over a 7.8 to 1 tuning range. By using spurious-free upper passband aperture-coupled cavity bandstop filters, multiple resonators, each with octave tuning, can cover a multioctave frequency range in a cascade. It is shown that the upper passband of this type of filter is limited by the reactance of the coupling apertures, which produce an unwanted in-band resonance unless designed properly. The details of this design process are explained and used to design a six-resonator bandstop filter cascade that is able to provide a bandstop filter response with up to 55 dB attenuation over the continuous band of 0.85-6.6 GHz. Through dynamic allocation of the cascade circuit's transmission zeros, one-, two-, three-, and four-pole bandstop filter responses of variable bandwidth can be realized over different frequency ranges, offering numerous bandwidth-attenuation level tradeoff combinations. View full abstract»

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  • Design Method for Ultra-Wideband Bandpass Filter With Wide Stopband Using Parallel-Coupled Microstrip Lines

    Page(s): 31 - 38
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    A method to design microstrip bandpass filters with ultra-wideband (UWB) performance, wide stopband, and practical dimensions is presented. According to the proposed method, three subsections of different lengths and coupling factors are connected to form a stepped-impedance parallel-coupled microstrip structure. A theoretical model is derived and used to find the optimum length and coupling factor for each of those subsections for an UWB passband and suppressed second and third harmonic responses in the stopband. The required performance is realized by generating and proper positioning of three transmission zeros in the upper stopband and three transmission poles in the passband. The derived model shows that the total length of the three-subsection coupled structure is one-third of the effective wavelength at the center of the passband. The theoretical model is used to find the required design values for the whole structure. The presented method is validated by building a bandpass filter that has a passband from 3.1 to 10.6 GHz with less than 1-dB insertion loss and a wide upper stopband that extends up to 28 GHz. View full abstract»

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  • Design of a Broadband Eight-Way Coaxial Waveguide Power Combiner

    Page(s): 39 - 45
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    In this paper, a broadband high-power eight-way coaxial waveguide power combiner with axially symmetric structure is proposed. A combination of circuit model and full electromagnetic wave methods is used to simplify the design procedure by increasing the role of the circuit model and, in contrast, reducing the amount of full wave optimization. The presented structure is compact and easy to fabricate. Keeping its return loss greater than 12 dB, the constructed combiner operates within 112% bandwidth from 520 to 1860 MHz. View full abstract»

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  • K -Band CMOS Differential and Quadrature Voltage-Controlled Oscillators for Low Phase-Noise and Low-Power Applications

    Page(s): 46 - 59
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    In this paper, modified circuit topologies of a differential voltage-controlled oscillator (VCO) and a quadrature VCO (QVCO) in a standard bulk 90-nm CMOS process are presented for low dc power and low phase-noise applications. By utilizing current-reuse and transformer-feedback techniques, the proposed VCO and QVCO can be operated at reduced dc power consumption while maintaining extraordinary circuit performance in terms of low phase-noise and low amplitude/phase errors. The VCO circuit topology is investigated to obtain the design procedure. The VCO is further applied to the QVCO design with a bottom-series coupling technique. The coupling network between two differential VCOs and device size are properly designed based on our proposed design methodology to achieve low amplitude and phase errors. Moreover, the VCO and the QVCO are fully characterized with amplitude and phase errors via a four-port vector network analyzer. With a dc power of 3 mW, the VCO exhibits a frequency tuning range from 20.3 to 21.3 GHz, a phase noise of - 116.4 dBc/Hz at 1-MHz offset, a figure-of-merit (FOM) of -198 dBc/Hz, a phase error of 3.8° , and an amplitude error of 0.9 dB. With a dc power of 6 mW, the QVCO demonstrates a phase noise of -117.4 dBc/Hz, a FOM of -195.6 dBc/Hz, a phase error of 4° , and an amplitude error of 0.6 dB. The proposed VCO and QVCO can be compared with the previously reported state-of-the-art VCOs and QVCOs in silicon-based technologies. View full abstract»

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  • Low-Voltage K -Band Divide-by-3 Injection-Locked Frequency Divider With Floating-Source Differential Injector

    Page(s): 60 - 67
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    This paper presents the design of a direct-injection divide-by-3 frequency divider operating at the K -band. The divider is implemented in a 0.18- μm CMOS process. The measured free-running frequency of the divider is 7.96 GHz. By utilizing a floating-source differential injector and without a varactor tuning in the divider core, the total locking range is 3.2 GHz with a power consumption of 8.28 mW from a supply voltage of 0.9 V. The total power consumption of the buffers is 9.54 mW from a supply voltage of 1.8 V. The measured phase noise of the divider is -141.3 dBc/Hz at 1-MHz offset when the input referred signal with a phase noise of -132.8 dBc/Hz at 1-MHz offset from 24 GHz. The phase-noise difference of 8.5 dB is close to the theoretical value of 9.5 dB for division-by-3. The output power of the divider is more than -11 dBm over the whole locking range. View full abstract»

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  • Compact Wideband Linear CMOS Variable Gain Amplifier for Analog-Predistortion Power Amplifiers

    Page(s): 68 - 76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2856 KB) |  | HTML iconHTML  

    To predistort the signal of an analog-predistortion power amplifier system, this paper proposes a variable gain amplifier (VGA) topology that gives an optimized linearity and bandwidth performance while having a continuous, linear-in-decibel gain control curve. The design employs a self-biased differential amplifier with a dynamic current source to provide gain and linearity. The overall VGA gain is then controlled by a highly linear variable attenuator connected at the output of the amplifier. This separated controlling stage allows the VGA to have a continuous and linear-in-decibel gain curve without sacrificing the bandwidth and linearity of its amplifier stage. A VGA designed with such topology has been fabricated in a standard 0.18- μm CMOS technology. Targeted for wideband code-division multiple-access applications, the VGA has a maximum gain tuning range from -13.5 to 13.5 dB, a bandwidth better than 1.8 GHz (380 MHz to 2.2 GHz), and a worst case input P1dB better than -5 and -3.6 dBm, respectively, at 850 MHz and 1.95 GHz. The post-attenuated structure also gives the VGA a noise figure as low as of 4.9 dB at 1.95 GHz. To our knowledge, the design demonstrates the best linearity performance and has other characteristics that are equivalent with other VGAs. View full abstract»

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  • A Dual-Mode CMOS RF Power Amplifier With Integrated Tunable Matching Network

    Page(s): 77 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1980 KB) |  | HTML iconHTML  

    A dual-mode CMOS power amplifier (PA) with an integrated tunable matching network is presented. A switched capacitor is fully analyzed to implement a tunable matching network in terms of power-handling capability, tuning ratio, quality factor, and linearity. Based on the presented consideration, a 3.3-V 2.4-GHz fully integrated CMOS dual-mode PA is implemented in a 0.18-μm CMOS process. The PA has two power modes, high-power and low-power (LP), and each mode is optimally matched by the tunable matching network. The LP mode enables more than 50% dc current reduction from 0- to 10-dBm power range. The improved efficiency in this study is approximately twice that of other multimode CMOS PAs reported thus far. View full abstract»

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  • Switching Behavior of Class-E Power Amplifier and Its Operation Above Maximum Frequency

    Page(s): 89 - 98
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    The switching behavior of Class-E power amplifiers (PAs) is described. Although the zero voltage switching can be performed properly, the Cout charging process at the switch-off transition cannot be abrupt and the waveform deviates from the ideal shape, degrading the efficiency. For the operation above maximum frequency, the charging process should be even faster but it cannot follow. Moreover, the discharging process is not sufficiently fast and further degrades the efficiency. The discharging process is assisted by the bifurcated current at saturation. The performance of the Class-E PA above the maximum frequency is enhanced by the nonlinear Cout, which helps to shape the voltage waveform. The bifurcated current itself cannot generate enough of a second-harmonic voltage component to shape the required voltage waveform. The performance of the Class-E PA can be further improved by a second-harmonic tuning and a conjugate matched output load, leading to the saturated PA. Compared with the Class-E PA, the saturated amplifier delivers higher output power and efficiency. A highly efficient saturated amplifier is designed using a Cree GaN HEMT CGH40010 device at 3.5 GHz. It provides a drain efficiency of 75.8% at a saturated power of 40.2 dBm (10.5 W). View full abstract»

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  • Broadband Doherty Power Amplifier via Real Frequency Technique

    Page(s): 99 - 111
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    A comprehensive method of designing a broadband Doherty power amplifier is presented in this paper. The essential limitations of bandwidth extension of a Doherty power amplifier are discussed based on the proposed structure of the Doherty power amplifier, which also takes the output matching networks of both sub-amplifiers into account. The broadband matching is realized by applying the simplified real frequency technique with the desired frequency-dependent optimum impedances. GaN transistors were selected to implement the circuit structure. View full abstract»

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  • A 17–35 GHz Broadband, High Efficiency PHEMT Power Amplifier Using Synthesized Transformer Matching Technique

    Page(s): 112 - 119
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    This paper presents a 17 GHz to 35 GHz broadband power amplifier (PA) using 0.15-μm GaAs pHEMT technology. The synthesized transformer using microstrip line matching technique is proposed in this PA design to enhance the broadband frequency response and minimize the chip size. The design procedures are also presented. A high efficiency broadband PA in commercial 0.15 μm GaAs pHEMT process with the best P1dB of 22 dBm, Psat of 23.5 dBm, and PAE of 40% are demonstrated to verify the design concepts. This PA has the highest PAE, smallest chip size, and wide fractional bandwidth among the broadband GaAs HEMT PAs from K to Ka band. View full abstract»

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  • A 50-Mb/s CMOS QPSK/O-QPSK Transmitter Employing Injection Locking for Direct Modulation

    Page(s): 120 - 130
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1445 KB) |  | HTML iconHTML  

    A 50-Mb/s quadrature phase-shift keying (QPSK)/offset quadrature phase-shift keying (O-QPSK) transmitter suitable for biomedical high-quality imaging application is presented. Centered at 915 MHz, the phase modulation is achieved by directly modifying the self-resonant frequency of an LC voltage-controlled oscillator through capacitor bank switching. By eliminating many unnecessary building blocks in the conventional QPSK/O-QPSK transmitter, significant power and area savings are achieved. Implemented in 0.18- μm CMOS technology, it occupies an active core area of 0.28 mm2. With 305-MHz injection frequency and consuming 5.6 mW under 1.4-V supply, the transmitter achieves error vector magnitude (EVM) of 11.4%/5.97% for O-QPSK/QPSK modulation while delivering output power of -3 dBm at 50 Mb/s. By lowering the injection frequency to 101.67 MHz, it consumes 5.88 mW under the same supply voltages while delivering an output power of -3.3 dBm. The transmitter achieves measured EVM of 6.4% at 50 Mb/s under QPSK modulation. View full abstract»

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  • An Open-Loop Half-Quadrature Hybrid for Multiphase Signals Generation

    Page(s): 131 - 138
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    In this paper, a passive half-quadrature hybrid (HQH) is presented for multiphase signal generation at radio frequencies. Utilizing capacitance ratios as the primary design parameters, the proposed hybrid exhibits excellent magnitude and phase balance even in the presence of process and temperature variations. Therefore, it is well suited for integrated-circuit designs with on-chip capacitive elements. Using a standard 0.18-μm CMOS process, the HQH circuit is integrated with a 5.6-GHz quadrature voltage-controlled oscillator (QVCO) and four down-conversion mixers for demonstration. As the QVCO oscillation frequency sweeps from 5.4 to 5.8 GHz, the measurement results indicate a root-mean-square (rms) magnitude error less than 0.5 dB and an rms phase error ranging from 4° to 7° at the half-quadrature outputs without any feedback correction. View full abstract»

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  • A Phased Array RFIC With Built-In Self-Test Capabilities

    Page(s): 139 - 148
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    An X-Band phased-array RF integrated circuit with built-in self-test (BIST) capabilities is presented. The BIST is accomplished using a miniature capacitive coupler at the input of each channel and an on-chip I/Q vector receiver. Systematic effects introduced with BIST system are covered in detail and are calibrated out of measurements. The BIST can be done at a rate of 1 MHz with 55 dB signal-to-noise-ratio and allows for the measurement of an on-chip array factor. Measurements done with BIST system agree well with S-parameter data over all test conditions. To our knowledge, this is the first implementation of an on-chip BIST with high accuracy. View full abstract»

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  • Fast Multiharmonic Active Load–Pull System With Waveform Measurement Capabilities

    Page(s): 149 - 157
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    A novel fast multiharmonic active load-pull system is presented, which allows for the acquisition of the complete voltage and current waveforms. The system is capable of measuring multiple different load impedance or input power states within a short time instance (typically 180 states within 20 ms). It also facilitates high-power capability (up to 100 W) and high-frequency operation (up to 50 GHz). Furthermore, the dynamic range at the higher order harmonics is significantly improved by introducing an equalizer in cascade with the wideband harmonic samplers. A new algorithm for presenting the wanted load impedance to the device-under-test is also proposed. The method allows for simultaneous optimization on multiple harmonics, converging within five iterations. This method is applicable to all open loop active load-pull systems and could significantly reduce the number of iterations, hence reducing the measurement time. This paper provides a detailed description of the measurement system, including on-wafer verification measurements. View full abstract»

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  • Broadband Electromagnetic Modeling of Woven Fabric Composites

    Page(s): 158 - 169
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    We demonstrate a new method for predicting the broadband electromagnetic (EM) wave propagation characteristics of woven fabric composites. The method combines a rigorous EM model with effective media theory to predict the EM properties of structural composites from dc to 50 GHz. Experimental results are provided that demonstrate the validity of the method. We also describe the presence of large narrow band electromagnetic resonances that occur above 30 GHz. These resonances, which are shown to be guided mode resonances, can be predicted by solving a simple dispersion relation. View full abstract»

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  • Low-DC Voltage-Controlled Steering-Antenna Radome Utilizing Tunable Active Metamaterial

    Page(s): 170 - 178
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    In this paper, we experimentally realized a steering antenna using a type of active metamaterial with tunable refractive index. The metamaterial is realized by periodically printed subwavelength metallic resonant patterns with embedded microwave varactors. The effective refractive index can be controlled by low direct-current (dc) bias voltage applied to the varactors. In-phase electromagnetic waves transmitting in different zones of such metamaterial slab experience different phase delays, and, consequently, the output direction of the transmitted wave can be steered with progressive phase shift along the interface. This antenna has a simple structure, is very easy to configure the beam direction, and has a low cost. Compared with conventional phased-array antennas, the radome approach has more flexibility to operate with different feeding antennas for various applications. View full abstract»

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  • Conformal Ink-Jet Printed C -Band Phased-Array Antenna Incorporating Carbon Nanotube Field-Effect Transistor Based Reconfigurable True-Time Delay Lines

    Page(s): 179 - 184
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    We present a conformal ink-jet printed 2-bit four-element phased-array antenna (PAA) without any lithography process. Passive and active components, such as microstrip transmission lines, phase shifters, and RF power distribution networks are all developed adopting a room-temperature printing process. The PAA working at 5.2 GHz is printed on flexible DuPont Kapton flexible printed circuit polyimide film to demonstrate the conformal nature. High-speed carbon-nanotube-based field-effect transistors (FETs) function as switches to route the RF signal go through different segments of the true-time delay lines. The FET switch exhibits an on-off ratio of over 1000 and current of 3.6 mA is obtained at a low source-drain bias of 0.8 V. The 2-bit azimuth beamsteering angles of the PAA are measured and confirmed to agree well with simulation values. View full abstract»

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  • Distortion Mechanisms Originating From Modal Noise in Radio Over Multimode Fiber Links

    Page(s): 185 - 194
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    Harmonic and intermodulation distortion contributions generated by modal noise in radio over multimode fiber (RoMMF) systems for in-building wireless coverage are reviewed. The role played by the launching technique and by the optical transmitter and receiver in an intensity-modulated direct-detection RoMMF system is described theoretically and experimentally. The presented results constitute a basis for the design of multiband RoMMF systems, where spurious emission due to distortions should be compliant with wireless standards both in downlink and uplink. View full abstract»

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  • The Performance of a Fiber-Optic Link Using Unbiased Balanced Photodiodes for Antenna Array Calibration

    Page(s): 195 - 200
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    A quadrature-biased dual-output Mach-Zehnder modulator is used to drive unbiased balanced photodiodes for use in antenna array applications. The RF gain is measured as a function of frequency and photocurrent. Balanced photodiode two-tone measurements at 6 GHz are compared with those of a single photodiode to show 26-dB suppression of the second-order distortion. This results in a second-order limited spur-free dynamic-range improvement of 12 dB. The phase error introduced in unbiased photodiodes is compared to that of the biased case to demonstrate that it would have minimal effect on the performance of the antenna array system. View full abstract»

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  • IEEE Transactions on Microwave Theory and Techniques information for authors

    Page(s): 202
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Aims & Scope

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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