Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 1998"
TL;DR: In this article, the electrostatic microswitch is used in a number of existing circuits and systems, including radio front-ends, capacitor banks, and time-delay networks, for quasi-optical beam steering and electrically reconfigurable antennas.
Abstract: This paper deals with a relatively new area of radio-frequency (RF) technology based on microelectro-mechanical systems (MEMS). RF MEMS provides a class of new devices and components which display superior high-frequency performance relative to conventional (usually semiconductor) devices, and which enable new system capabilities. In addition, MEMS devices are designed and fabricated by techniques similar to those of very large-scale integration, and can be manufactured by traditional batch-processing methods. In this paper, the only device addressed is the electrostatic microswitch - perhaps the paradigm RF-MEMS device. Through its superior performance characteristics, the microswitch is being developed in a number of existing circuits and systems, including radio front-ends, capacitor banks, and time-delay networks. The superior performance combined with ultra-low-power dissipation and large-scale integration should enable new system functionality as well. Two possibilities addressed here are quasi-optical beam steering and electrically reconfigurable antennas.
685Â citations
TL;DR: In this paper, a waveguide of new structure has been developed for millimeter-wave applications, which can be embedded in a substrate and is able to be wired in three dimensions, and its transmission characteristics are evaluated using a glass-ceramic substrate of dielectric constant, /spl epsiv/sub r/=5, and loss, tan /spl delta/=0.0008.
Abstract: A waveguide of new structure has been developed for millimeter-wave applications. The dielectric waveguide is constructed with sidewalls consisting of lined via-holes and edges of metallized planes. This structure can be manufactured by lamination techniques, so we refer to the waveguide as a "laminated waveguide". The laminated waveguide can be embedded in a substrate and is able to be wired in three dimensions. The transmission characteristics are evaluated using a glass-ceramic substrate of dielectric constant, /spl epsiv//sub r/=5, and loss, tan /spl delta/=0.0008. Insertion loss per unit length of the guide is estimated to be less than 0.5 dB/cm at 83 GHz. Furthermore, it was confirmed that the laminated waveguide is suitable to feeding lines for a small sized plane array antenna. By electromagnetic simulation, it has been confirmed that fundamental structures, such as bends, branches, power dividers, and interconnections between upper and lower layers can be realized with sufficient performances.
493Â citations
TL;DR: In this paper, a high-efficiency rectenna element has been designed and tested at 5.8 GHz for applications involving microwave-power transmission, which achieves an RF-to-DC conversion efficiency of 82% at an input power level of 50 mW and 327 /spl Omega/ load.
Abstract: A high-efficiency rectenna element has been designed and tested at 5.8 GHz for applications involving microwave-power transmission. The dipole antenna and filtering circuitry are printed on a thin duroid substrate. A silicon Schottky-barrier mixer diode with a low breakdown voltage is used as the rectifying device. The rectenna element is tested inside a waveguide simulator and achieves an RF-to-DC conversion efficiency of 82% at an input power level of 50 mW and 327 /spl Omega/ load. Closed-form equations are given for the diode efficiency and input impedance as a function of input RF power. Measured and calculated efficiency results are in good agreement. The antenna and circuit design are based on a full-wave electromagnetic simulator. Second harmonic power levels are 21 dB down from the fundamental input power.
483Â citations
TL;DR: The silicon-germanium heterojunction bipolar transistor (SiGe HBT) as mentioned in this paper is the first practical bandgap-engineered device to be realized in silicon and has achieved state-of-the-art performance.
Abstract: The silicon-germanium heterojunction bipolar transistor (SiGe HBT) is the first practical bandgap-engineered device to be realized in silicon. SiGe HBT technology combines transistor performance competitive with III-V technologies with the processing maturity, integration levels, yield, and hence, cost commonly associated with conventional Si fabrication. In the ten-and-one-half years since the first demonstration of a functional transistor, SiGe HBT technology has emerged from the research laboratory, entered manufacturing on 200-mm wafers, and is poised to enter the commercial RF and microwave market. State-of-the-art SiGe HBT's can deliver: (1) f/sub T/ in excess of 50 GHz; (2) f/sub max/ in excess of 70 GHz; (3) minimum noise figure below 0.7 dB at 2.0 GHz; (4) 1/f noise corner frequencies below 500 Hz; (5) cryogenic operation; (6) excellent radiation hardness; (7) competitive power amplifiers; and (8) reliability comparable to Si. A host of record-setting digital, analog, RF, and microwave circuits have been demonstrated in the past several years using SiGe HBT's, and recent work on passives and transmission lines on Si suggest a migratory path to Si-based monolithic microwave integrated circuits (MMIC's) is possible. The combination of SiGe HBT's with advanced Si CMOS to form an SiGe BiCMOS technology represents a unique opportunity for Si-based RF system-on-a-chip solutions. This paper reviews state-of-the-art SiGe HBT technology and assesses its potential for current and future RF and microwave systems.
479Â citations
TL;DR: In this paper, a coplanar waveguide (CPW) transmission line with fixed-fixed beam MEMS bridge capacitors placed periodically over the transmission line, thus creating a slow-wave structure was designed.
Abstract: Wide-band switches and true-time delay (TTD) phase shifters have been developed using distributed microelectromechanical system (MEMS) transmission lines for applications in phased-array and communication systems. The design consists of a coplanar waveguide (CPW) transmission line (W=G=100 /spl mu/m) fabricated on a 500 /spl mu/m quartz substrate with fixed-fixed beam MEMS bridge capacitors placed periodically over the transmission line, thus creating a slow-wave structure. A single analog control voltage applied to the center conductor of the CPW line can vary the phase velocity of the loaded line by pulling down on the MEMS bridges to increase the distributed capacitive loading. The resulting change in the phase velocity yields a TTD phase shift. Alternatively, the control voltage can be increased beyond the pull-down voltage of the MEMS bridges such that the capacitive loading greatly increases and shorts the line to ground. The measured results demonstrate 0-60 GHz TTD phase shifters with 2 dB loss/118/spl deg/ phase shift at 60 GHz (/spl sim/4.5-ps TTD) and 1.8 dB loss/84/spl deg/ phase shift at 40 GHz. Also, switches have been demonstrated with an isolation of better than 40 dB from 21 to 40 and 40 to 60 GHz. In addition, a transmission-line model has been developed, which results in very close agreement with the measured data for both the phase shifters and switches. The pull-down voltage is 10-23 V, depending on the residual stress in the MEMS bridge. To our knowledge, this paper presents the first wide-band TTD MEMS phase shifters and wide-band switches to date.
440Â citations
TL;DR: In this article, a two-and three-plate tunable capacitors with two and three parallel plates have been fabricated using a standard polysilicon surface micromachining process.
Abstract: Micromachined electro-mechanically tunable capacitors with two and three parallel plates are presented. Experimental devices have been fabricated using a standard polysilicon surface micromachining process. The two-plate tunable capacitor has a measured nominal capacitance of 2.05 pF, a Q-factor of 20 at 1 GHz, and achieves a tuning range of 1.5:1, The three-plate version has a nominal capacitance of 4.0 pF, a Q-factor of 15.4 at 1 GHz, and a tuning range of 1.87:1. The tuning ranges achieved here are near theoretical limits. Effects due to various physical phenomena such as temperature, gravity, and shock are examined in detail. An RF voltage-controlled oscillator with an integrated inductor and a micromachined tunable capacitor is also demonstrated. The active circuit and the inductor have been fabricated in a 0.5 /spl mu/m CMOS process. The voltage-controlled oscillator has been assembled by bonding together the CMOS and the micromachined parts. The 1.35 GHz voltage-controlled oscillator has a phase noise of -98.5 dBc/Hz at a 100 kHz offset from the carrier.
275Â citations
TL;DR: In this paper, a rectenna array with an area of 3.2 m/spl times/3.6 m was constructed for a field experiment on microwave power transmission (MPT) which was jointly conducted by the Radio Atmospheric Science Center of Kyoto University, Robe University, and Kansai Electric Power Company from 1994 to 1995.
Abstract: For a field experiment on microwave power transmission (MPT) which was jointly conducted by the Radio Atmospheric Science Center of Kyoto University, Robe University, and Kansai Electric Power Company from 1994 to 1995, we had developed and tested a new type of rectenna (rectifying antenna) based on a circular microstrip antenna (CMA). A square shape of array with an area of 3.2 m/spl times/3.6 m was then constructed using the developed rectennas for experiment. The whole rectenna array is composed of 256 sub-arrays, each with nine rectenna elements. We place the rectenna sub-array with better RF-DC conversion efficiency in the central area of the whole rectenna array. Such spatial optimization is needed because the power density of the microwave beam used in the experiment has a spatial gradient with a peak at the center of the beam. We then examined dependence of the rectenna array characteristics on the electrical connection of the sub-arrays. The difference of the output DC power of the whole array for five different electrical connections is within 5%. The load characteristics, therefore, suffers little change even if the electrical connection of the rectenna sub-array is changed.
245Â citations
TL;DR: In this paper, a new class of cross-coupled planar microwave filters using microstrip hairpin resonators is introduced, and the theoretical and experimental performance of these filters are investigated in the light of full-wave electromagnetic simulations.
Abstract: A new class of cross-coupled planar microwave filters using microstrip hairpin resonators is introduced. The realization of bath the canonical and the cascaded quadruplet (CQ) filters is feasible. Coupling characteristics of four basic coupling structures encountered in this class of filters are investigated in the light of full-wave electromagnetic (EM) simulations. A four-pole cross-coupled filter of this type is designed and fabricated. Both the theoretical and experimental performance is presented.
229Â citations
TL;DR: Injection-locking and phase-locked-loop (PLL) techniques can be used to achieve synchronous operation of a number of antenna array elements, and allow for the manipulation of the phase distribution without additional phase-shifting circuitry as discussed by the authors.
Abstract: Applications of millimeter-wave radar, imaging, and communication technology requires cost-effective implementation of intelligent scanning antenna systems Injection-locking and phase-locked-loop (PLL) techniques can be used to achieve synchronous operation of a number of antenna array elements, and allow for the manipulation of the phase distribution without additional phase-shifting circuitry, suggesting a potential for low-cost beam-scanning systems This paper describes a number of techniques, with an assessment of some remaining technical challenges for practical implementation
228Â citations
TL;DR: In this paper, a 20-W peak-envelope power linear L-band transmitter based upon the Kahn envelope-elimination-andrestoration technique is described, which achieves an efficiency of 56% at full power (41 dBm), and 35% at 18 dB into back-off.
Abstract: This paper describes a 20-W peak-envelope power linear L-band transmitter based upon the Kahn envelope-elimination-and-restoration technique. A double envelope-feedback loop assures high linearity. The radio-frequency (RF) power amplifier employs a two-stage monolithic-microwave integrated-circuit driver amplifier and a 20-W power amplifier biased for class-AB operation. The class-S modulator includes a high-speed comparator and 1/2-/spl mu/m heterojunction field-effect transistors in its output stage. A double envelope-feedback loop assures both high linearity and time-delay equalization for RF bandwidths to 150 kHz. With a two-tone signal, the transmitter achieves an efficiency of 56% at full power (41 dBm), and 35% at 18 dB into back-off. The third-order intermodulation distortions for a two-tone signal vary from -30 to -40 dBc over a 20-dB range of back-off. For quaternary phase-shift keying, the first and second adjacent-channel powers are -48 and -57 dBc.
212Â citations
TL;DR: In this paper, the specific absorption rate (SAR) distribution in a human-eye anatomical model, developed from the "visible human" data set, by using the finite-difference time-domain (FDTD) numerical technique with a cell resolution of 0.5 mm.
Abstract: Wireless personal communication is a rapidly expanding sector, particularly in the field of cellular mobile phones and wireless local area networks (WLAN's). In an indoor WLAN system, the user of the mobile terminal can find himself in close proximity to the radiating antenna. It is, therefore, important to consider possible health hazards due to this type of exposure. As the most considered adverse effects of the electromagnetic (EM) fields are of thermal nature, particularly with reference to the eye, in this paper, the authors have evaluated the temperature increase induced in a human eye exposed to WLAN-like fields. In particular, they have considered possible WLAN's operating in the range between 6-30 GHz, so that the incident field can be simulated via a plane wave. As a first step, the authors have computed the specific absorption rate (SAR) distribution in a human-eye anatomical model, developed from the "visible human" data set, by using the finite-difference time-domain (FDTD) numerical technique with a cell resolution of 0.5 mm. Starting from the calculated SAR values, the heating distribution has been derived through the bioheat equation, which has been solved using an explicit finite-difference scheme. Temperature increases of the order of 0.04/spl deg/C have been calculated in the eye lens with an incident power density of 1 mW/cm/sup 2/ at 6 GHz. Lower heating is obtained in the lens when the frequency increases. Finally, considerations about the exposure limits in the considered frequency range are made.
TL;DR: In this paper, a planar active-lens amplifier with a microstrip-fed Yagi-Uda slot-array antenna for TM surface-wave excitation of a thick dielectric slab is presented.
Abstract: Power combining of TM surface waves by a planar active-lens amplifier is the subject of this paper. An amplifier gain of 11 dB at 8.25 GHz with a 3-dB bandwidth of 0.65 GHz has been demonstrated. Gain is measured from input to output connector to facilitate comparisons with more conventional amplifiers. Measurements of output power versus input power are also presented. The amplifier behaved in a linear manner and no problems with spurious oscillations were encountered. Construction of the amplifier is compatible with planar fabrication technologies. A key component of the combiner is a microstrip-fed Yagi-Uda slot-array antenna for TM surface-wave excitation of a thick dielectric slab. Design and optimization guidelines for the antenna are presented as well as detailed spectral-domain and finite-difference time-domain (FDTD) analysis results. Measured and simulation results show an input return loss and front-to-back ratio better than 10 dB over a 5% bandwidth. Calculated and measured results for the fields radiated by the antenna confirm forward radiation of the dominant TM mode in the thick dielectric slab. Integration of the computed radiated fields shows the antenna has a surface-wave launching efficiency of 85%.
TL;DR: An overview of recent progress in the research and development of micromachined antennas, transmission lines, waveguides structures, and planar movable components for terahertz frequencies is presented in this article.
Abstract: An overview of recent progress in the research and development of micromachined antennas, transmission lines, waveguides structures, and planar movable components for terahertz frequencies is presented. Micromachining is shown to provide a low-cost alternative to conventional (and very expensive) machined-waveguide technology, resulting in antennas with excellent radiation patterns, low-loss tuners, and three-dimensional (3-D) micromachined structures suitable for terahertz applications. Fabrication procedures for a variety of micromachined waveguide and planar structures are described here, along with measured terahertz performance. Applications of micromachining techniques for terahertz systems include focal-plane imaging arrays requiring a large number of elements and low-cost receivers for commercial and industrial applications such as pollution monitoring.
TL;DR: Active integrated antennas (AIAs) provide a new paradigm for designing modern microwave and millimeter-wave architecture with desirable features such as compactness, light weight, low cost, low profile, minimum power consumption, and multiple functionality.
Abstract: Active integrated antennas (AIAs) provide a new paradigm for designing modern microwave and millimeter-wave architecture with desirable features such as compactness, light weight, low cost, low profile, minimum power consumption, and multiple functionality. This paper reviews recent research and development related to this emerging technology with emphasis on its applications in high-efficiency radio-frequency (RF) front-end, millimeter-wave power combining, beam steering, and retrodirective arrays, as well as wireless sensors. Optical controlling techniques for AIA's are also described.
TL;DR: In this article, high-performance planar micromachined filters at 37 and 60 GHz are presented, which consist of a 3.5% bandwidth two-pole Chebyshev filter with transmission zeros at 37 GHz, 2.7% and 4.3% bandwidth four-and five-pole chebbershev filters at 60 GHz, and an 8% bandwidth elliptic filter at 60GHz.
Abstract: High-performance planar micromachined filters at 37 and 60 GHz are presented. The filters consist of a 3.5% bandwidth two-pole Chebyshev filter with transmission zeros at 37 GHz, 2.7% and 4.3% bandwidth four- and five-pole Chebyshev filters at 60 GHz, and an 8% bandwidth elliptic filter at 60 GHz. Silicon micromachining techniques combined with micropackaging have been applied to allow for very high-Q resonators resulting in low-loss filters. The 37-GHz two-pole filter exhibits a 2.3-dB port-to-port insertion loss. The 2.7% and 4.3% four- and five-pole Chebyshev filters at 60 GHz exhibit 2.8- and 3.4-dB insertion loss, and the 8% elliptic filter exhibits a 1.5-dB insertion loss. These values show a large reduction of insertion loss compared to conventional planar techniques, and can be used for planar low-cost millimeter-wave wireless communication systems.
TL;DR: In this paper, a novel implementation of periodic boundary conditions incorporated into the finite-difference time-domain (FDTD) technique in both orthogonal and nonorthogonal grids is presented.
Abstract: A novel implementation of periodic boundary conditions incorporated into the finite-difference time-domain (FDTD) technique in both orthogonal and nonorthogonal grids is presented in this paper. The method applied is a field-splitting approach to the discretization of the Floquet-transformed Maxwell equations. As a result, the computational burden is reduced and the stability criterion is relaxed. The results of the two methods are compared to experimental data.
TL;DR: In this paper, a new measurement technique for repetitive microwave signals that is applied to modeling wideband power amplifiers is presented, which includes a filter before the memoryless nonlinearity to capture the memory effects associated with wideband signals.
Abstract: This paper presents a new time-domain measurement technique for repetitive microwave signals that is applied to modeling wideband power amplifiers. The measurement technique concept consists of recording the microwave signal after conversion to baseband using a calibrated downconverter, which improves measurement accuracy compared to measurements at the carrier frequency. The modeling section describes how such time-domain measurements can be used to model wideband signal effects in nonlinear power amplifiers. The commonly used memory-less envelope model is limited to use on narrowband signals. A new model is developed which includes a filter before the memory-less nonlinearity to capture the memory effects associated with wideband signals. It is demonstrated that the accuracy of wideband signal simulations can be improved by optimizing the model parameters based on time-domain measurements of wideband signals.
TL;DR: In this paper, a design-oriented analysis of the microwave transmission-line class-E amplifier is presented, and experiments and harmonic-balance circuit simulations verify the theoretical equations which predict class-e-amplifier output power, maximum frequency of operation, and dc-RF conversion efficiency.
Abstract: A design-oriented analysis of the microwave transmission-line class-E amplifier is presented. Experiments and harmonic-balance circuit simulations verify the theoretical equations which predict class-E-amplifier output power, maximum frequency of operation, and dc-RF conversion efficiency. Experimental results at 0.5, 1,2, and 5 GHz are presented. At 0.5 GHz, 83% drain efficiency and 80% power-added efficiency (PAE) are measured, with an output power of 0.55 W, using the Siemens CLY5 MESFET. These results are compared to a class-A and class-F power amplifier using the same device. At 5 GHz, 81% drain efficiency and 72% PAE are measured, with an output power of 0.61 W, using the Fujitsu FLK052WG MESFET. Finally, the 5-GHz class-E power amplifier is successfully integrated into an active-antenna array, demonstrating power combining of four elements with an 85% power-combining efficiency. At 5.05 GHz, the class-E power-amplifier antenna array delivers a total of 2.4 W of output power, with a dc-RF conversion efficiency of 74% and a PAE of 64%.
TL;DR: In this paper, a hybrid approach combining the finite-difference time-domain (FDTD) analysis and harmonic-balance simulation is employed for high-efficiency power amplifiers.
Abstract: This paper presents three novel architectures for high-efficiency amplifiers relying on new harmonic-tuning techniques. These methods yield high-efficiency power amplifiers and reduce unwanted harmonic radiation from the transmitter front end. The first method uses the active integrated-antenna approach to perform harmonic tuning. The second method uses a nontraditional periodic microstrip filter, which allows broadband harmonic tuning. Finally, the third method combines the previous two approaches. Each technique is illustrated by a design example of a power amplifier integrated with an antenna. Guidelines for choosing the appropriate antenna structure and for designing the periodic structures are also presented. Another design issue is inclusion of the antenna and/or periodic structures into the amplifier simulation. To do this, a hybrid approach combining the finite-difference time-domain (FDTD) analysis and harmonic-balance simulation is employed.
TL;DR: In this paper, the group delay of the input reflection coefficients of sequentially tuned resonators has been shown to provide all the information necessary to design and tune filters, and that the group-delay value at the center frequency of the filter can be written quite simply in terms of the low pass prototype values, the LC elements of a bandpass structure, and the coupling coefficients of the inverter coupled filter.
Abstract: The concept of coupling coefficients has been a very useful one in the design of small-to-moderate bandwidth microwave filters. It is shown in this paper that the group delay of the input reflection coefficients of sequentially tuned resonators contains all the information necessary to design and tune filters, and that the group-delay value at the center frequency of the filter can be written quite simply in terms of the low-pass prototype values, the LC elements of a bandpass structure, and the coupling coefficients of the inverter coupled filter. This provides an easy method to measure the key elements of a filter, which is confirmed by results presented in this paper. It is also suggested that since the group delay of the reflection coefficient (i.e., the time taken for energy to get in and out of the coupled resonators) is easily measured, it is a useful conceptual alternative to coupling concepts.
TL;DR: In this paper, an original multimode thru-reflection line (TRL) algorithm is used to derive the generalized scattering parameters of multimode two-port networks, and theoretical developments are detailed for calibration procedures based on two ports as well as multiple-port vector network analyzer measurements.
Abstract: An original multimode thru-reflection line (TRL) algorithm is used to derive the generalized scattering parameters of multimode two-port networks. Theoretical developments are detailed for calibration procedures based on two ports as well as multiple-port vector network analyzer (VNA) measurements. First-run experimental results demonstrate the validity of this technique. This method allows the experimental characterization of multiconductor transmission-line devices. It could also be used to characterize power coupling to undesired modes in monolithic microwave integrated circuit (MMIC) structures using conductor-backed coplanar waveguides.
TL;DR: In this paper, the authors describe the development and characterization of a new class of Si-micromachined lines and circuit components for operation between 2-110 GHz, which are a finite-ground coplanar-waveguide (FGC) type, Si micromachining is used to remove the dielectric material from the aperture regions in an effort to reduce dispersion and minimize propagation loss.
Abstract: This paper describes the development and characterization of a new class of Si-micromachined lines and circuit components for operation between 2-110 GHz. In these lines, which are a finite-ground coplanar-waveguide (FGC) type, Si micromachining is used to remove the dielectric material from the aperture regions in an effort to reduce dispersion and minimize propagation loss. Measured results have shown a considerable loss reduction to levels that compare favorably with those of membrane lines and rectangular waveguides. Micromachined FGC lines have been used to develop V- and W-band bandpass filters. The W-band micromachined FGC filter has shown a 0.8-dB improvement in insertion loss at 94 GHz over a conventional FGC line. This approach offers an excellent alternative to the membrane technology, exhibiting very low loss, no dispersion, and mode-free operation without using membranes to support the interconnect structure.
TL;DR: In this article, the authors presented simple correct models of high-temperature superconductor (HTS) film parameters at microwave frequencies, based on the enhanced two-fluid model of a super-conductor.
Abstract: This paper presents simple correct models of high-temperature superconductor (HTS) film parameters at microwave frequencies. The models are based on the enhanced two-fluid model of a superconductor. The quasi-particle scattering and peculiarities of the normal conductivity of the HTS at microwaves, including residual resistance of a material, are taken into account. The difference between the known Gorter and Casimir two-fluid model of low-temperature superconductor and the enhanced two-fluid model of HTS is proven. A simple quasi-static model of current distribution across the microstrip line and coplanar waveguide is used for a simulation of a contribution of the superconductor transport processes into impedance per unit length of the transmission lines considered. The models developed were applied to a simulation of microstrip line and coplanar waveguide resonators. Good agreement of simulated results and measurements in a wide temperature range has been demonstrated. The model presented can be considered as a starting point for the formation of the computer-aided design (CAD) package of HTS microwave components.
TL;DR: The technological background as well as active and nonlinear devices and passive circuit structures suitable for silicon- and SiGe-based monolithic integrated millimeter-wave circuits are discussed.
Abstract: Monolithic integrated millimeter-wave circuits based on silicon and SiGe are emerging as an attractive option in the field of millimeter-wave communications and millimeter-wave sensors. The combination of active devices with passive planar structures, including also antenna elements, allows single-chip realizations of complete millimeter-wave front-ends. This paper reviews the state-of-the-art silicon- and SiGe-based monolithic integrated millimeter-wave circuits. The technological background as well as active and nonlinear devices and passive circuit structures suitable for silicon- and SiGe-based monolithic integrated millimeter-wave circuits are discussed. Examples of such integrated circuits and first systems applications are also presented.
TL;DR: In this paper, a prototype monopole-transceiver microwave imaging system has been implemented, and initial single and multitarget imaging experiments involving biologically relevant property distributions have been conducted to evaluate its performance relative to a previously developed waveguide system.
Abstract: A prototype monopole-transceiver microwave imaging system has been implemented, and initial single and multitarget imaging experiments involving biologically relevant property distributions have been conducted to evaluate its performance relative to a previously developed-waveguide system. A new, simplified, but more effective calibration procedure has also been devised and tested. Results show that the calibration procedure leads to improvements which are independent of the type of radiator used. Specifically, data-model match is found to increase by 0.4 dB in magnitude and 4/spl deg/ in phase for the monopoles and by 0.6 dB in magnitude and 7/spl deg/ in phase for the waveguides (on average) on a per measurement basis when the new calibration procedure is employed. Enhancements are also found in the reconstructed images obtained with the monopole system relative to waveguides. Improvements are observed in: 1) the recovered object shape; 2) the uniformity of the background; 3) edge detection; and 4) target property value recovery. Analyses of reconstructed images also suggest that there is a systematic decrease of approximately 10% in the reconstruction errors for the monopole system over its waveguide counterpart in single-target experiments and as much as a 20% decrease in multitarget cases. Results indicate that these enhancements stem from a better data-model match for the monopoles relative to waveguides which is consistent across the type of calibration procedure used. Comparisons of computations and measurements show an average improvement in data-model match of approximately 0.25 dB in magnitude and near 7/spl deg/ in phase in favor of the monopoles in this regard. Beyond this apparent imaging performance enhancement, the monopole system offers economy-of-space and low construction-cost considerations along with computational advantages (as described herein) which make it a compelling choice as a radiator/receiver element around which to construct a clinically viable near-field microwave imaging system.
TL;DR: In this article, a remote heterodyne detection (RHD) of signals from a dual-frequency laser transmitter is discussed and experimentally demonstrated and the resulting links are inherently transparent.
Abstract: The multifunctionality of microwave links based on remote heterodyne detection (RHD) of signals from a dual-frequency laser transmitter is discussed and experimentally demonstrated in this paper. Typically, direct detection (DD) in conjunction with optical intensity modulation is used to implement fiber-optic microwave links. The resulting links are inherently transparent. As opposed to DD links, RHD links can perform radio-system functionalities such as modulation and frequency conversion in addition to transparency. All of these three functionalities are presented and experimentally demonstrated with an RHD link based on a dual-frequency laser transmitter with two offset phase-locked semiconductor lasers. In the modulating link, a 1-Gb/s baseband signal is QPSK modulated onto a 9-GHz RF carrier. The frequency converting link demonstrates up-conversion of a 100-Mb/s PSK signal from a 2-GHz carrier to a 9-GHz carrier with penalty-free transmission over 25 km of optical fiber. Finally, the transparent link transmits a standard FM video 7.6-GHz radio-link signal over 25 km of optical fiber without measurable distortion.
TL;DR: In this paper, a poly-to-n-well MOS structure was used in a low-noise amplifier (LNA) with a resonant frequency of 960 MHz, power gain of 16.2 dB, 1-dB compression point (P/sub 1 dB/) of -5 dBm, and noise figure of 3.5 dB was demonstrated.
Abstract: In a foundry 0.8-/spl mu/m CMOS process, low-cost capacitors with a measured Q factor of around 50 at 3 GHz and high intrinsic capacitance/area (/spl sim/200 nF/cm/sup 2/) were demonstrated. When extrapolated to 900 MHz, the Q factor is greater than 100. The capacitors use a poly-to-n-well MOS structure which has been commonly dismissed for high-Q applications due to the high n-well sheet resistance (/spl sim/1 k/spl Omega///spl square/). Utilizing the structure, a low-noise amplifier (LNA) with a resonant frequency of 960 MHz, power gain of 16.2 dB, 1-dB compression point (P/sub 1 dB/) of -5 dBm, and noise figure of 3.5 dB was demonstrated. Using a rule of thumb, the third-order harmonic intercept point (P/sub IP3/) was estimated to be 5 dBm from the P/sub 1 dB/ data. Despite concerns for nonlinearity of the capacitors, these results suggest that this capacitor structure could be used in LNA's with a large dynamic range.
TL;DR: In this article, a quasi-TEM equivalent circuit model was developed from the available process parameters, which accounts for the effects of the electromagnetic fields in the coplanar waveguides (CPW) structure over a broad frequency range.
Abstract: This paper presents characteristics of microwave transmission in coplanar waveguides (CPW's) on silicon (Si) substrates fabricated through commercial CMOS foundries. Due to the CMOS fabrication, the metal strips of the CPW are encapsulated in thin films of Si dioxide. Many test sets were fabricated with different line dimensions, all on p-type substrates with resistivities in the range from 0.4 /spl Omega//spl middot/cm to 12.5 /spl Omega//spl middot/cm. Propagation constant and characteristic impedance measurements were performed at frequencies from 0.1 to 40 GHz, using a vector-network analyzer and the through-reflect-line (TRL) deembedding technique. A quasi-TEM equivalent circuit model was developed from the available process parameters, which accounts for the effects of the electromagnetic fields in the CPW structure over a broad frequency range. The analysis was based on the conformal mapping of the CPW multilayer dielectric cross section to obtain accurate circuit representation for the effects of the transverse fields.
TL;DR: In this article, a fully integrated 850 MHz, two-pole, bandpass filter with an 18 MHz 3 dB bandwidth is reported. And the prototype design is implemented in a standard 0.8 /spl mu/m CMOS process and achieves a rejection of over 50 dB at 100 MHz offset, an in-band dynamic range of 75 (90) dB when used in a system with a 1 MHz (30 kHz) final IF bandwidth, and a third-order intercept point that exceeds +25 dBm at an 80 MHz offset from the passband center.
Abstract: Q-enhanced LC filter technology offers an alternative to the use of direct conversion techniques for implementing fully integrated receivers. Design and performance issues for QE LC filters are discussed and a fully integrated 850 MHz, two-pole, bandpass filter with an 18 MHz 3 dB bandwidth is reported. The prototype design is implemented in a standard 0.8 /spl mu/m CMOS process and achieves a rejection of over 50 dB at 100 MHz offset, an in-band dynamic range of 75 (90) dB when used in a system with a 1 MHz (30 kHz) final IF bandwidth, and a third-order intercept point that exceeds +25 dBm at an 80 MHz offset from the passband center,.
TL;DR: In this paper, the first-order effects of flip-chip transitions are identified and design criteria for millimeter-wave multichip interconnects are derived. But the performance of the flipchip scheme can be evaluated properly only in conjunction with the actual motherboard packaging setup.
Abstract: Electromagnetic simulation and measurement data of flip-chip transitions are presented. First-order effects are identified and design criteria for millimeter-wave multichip interconnects are derived. Results cover chip detuning and bump geometry as well as simplified modeling. In a coplanar environment, the flip-chip scheme provides interconnects with excellent low-reflective properties. For conductor-backed structures, parasitic modes occur leading to unwanted crosstalk. These effects dominate the behavior so that overall performance of the flip-chip scheme can be evaluated properly only in conjunction with the actual motherboard packaging setup.