Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 2005"
TL;DR: In this paper, a new approach for the development of planar metamaterial structures is developed, and analytical equivalent circuit models are proposed for isolated and coupled split-ring resonators/CSRRs coupled to planar transmission lines.
Abstract: In this paper, a new approach for the development of planar metamaterial structures is developed. For this purpose, split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs) coupled to planar transmission lines are investigated. The electromagnetic behavior of these elements, as well as their coupling to the host transmission line, are studied, and analytical equivalent-circuit models are proposed for the isolated and coupled SRRs/CSRRs. From these models, the stopband/passband characteristics of the analyzed SRR/CSRR loaded transmission lines are derived. It is shown that, in the long wavelength limit, these stopbands/passbands can be interpreted as due to the presence of negative/positive values for the effective /spl epsiv/ and /spl mu/ of the line. The proposed analysis is of interest in the design of compact microwave devices based on the metamaterial concept.
1,405 citations
TL;DR: A classification of the various PA behavioral models is proposed, discussing their abilities to represent the different effects observed in practical circuits and how it was possible to integrate a wide range of behavioral modeling activities.
Abstract: This paper presents a comparative overview of the most important approaches presented to address the behavioral modeling of microwave and wireless power amplifiers (PAs). Starting from a theoretical framework of recursive and nonrecursive nonlinear filters, it proposes a classification of the various PA behavioral models, discussing their abilities to represent the different effects observed in practical circuits. Using that formal procedure, one explains how it was possible to integrate a wide range of behavioral modeling activities and to show that some of them, which at first glance seemed to be quite different, are, indeed, identical in their modeling capabilities.
441 citations
TL;DR: In this article, the authors highlight a large variety of physical effects associated with double and single negative metamaterials and some of their very interesting potential applications, including the potential to engineer materials with desired electric and magnetic properties to achieve unusual physical effects.
Abstract: Metamaterials (MTMs), which are formed by embedding inclusions and material components in host media to achieve composite media that may be engineered to have qualitatively new physically realizable response functions that do not occur or may not be easily available in nature, have raised a great deal of interest in recent years. In this paper, we highlight a large variety of the physical effects associated with double- and single-negative MTMs and some of their very interesting potential applications. The potential ability to engineer materials with desired electric and magnetic properties to achieve unusual physical effects offers a great deal of excitement and promise to the scientific and engineering community. While some of the applications we will discuss have already come to fruition, there are many more yet to be explored.
433 citations
TL;DR: In this paper, a set of design criteria for the radio-frequency (RF) section of long-range passive RF identification (RFID) transponders operating in the 2.45 GHz or 868-MHz industrial, scientific, and medical (ISM) frequency ranges is derived in particular on the voltage multiplier, the power-matching network, and the backscatter modulation.
Abstract: A set of design criteria for the radio-frequency (RF) section of long-range passive RF identification (RFID) transponders operating in the 2.45-GHz or 868-MHz industrial, scientific, and medical (ISM) frequency ranges is derived in this paper, focusing in particular on the voltage multiplier, the power-matching network, and the backscatter modulation. The paper discusses the design tradeoffs between the error probability at the reader receiver and the converted RF-dc power at the transponder, determining the regions of the design space that allow optimization of the operating range and the data rate of the RFID system.
420 citations
TL;DR: In this paper, the power reflection coefficient from the Smith chart was applied to passive RFID tag design, where power reflection is important, as it determines the tag characteristics. But the performance analysis of a specific RFID was presented together with experimental data, which was in close agreement with the theory.
Abstract: Kurokawa's method of calculating the power reflection coefficient from the Smith chart in the situation when one complex impedance is directly connected to another is applied to passive RFID tag design, where power reflection is important, as it determines the tag characteristics. The performance analysis of a specific RFID tag is presented together with experimental data, which is in close agreement with the theory.
332 citations
Abstract: An efficiency-enhanced power-amplifier system design is presented based on wide-bandwidth envelope tracking (WBET) with application to orthogonal frequency-division multiplexing wireless local area network systems. Envelope elimination and restoration (EER) and WBET are compared in terms of the time mismatch sensitivity between the base-band amplitude path and the RF path, and it is demonstrated that WBET is much less sensitive than EER to these effects. An adaptive time-alignment algorithm for the WBET system is developed and demonstrated. The analysis and algorithm are verified by experimental results. The measurement shows that the peak drain efficiency of the complete system was 30% at a 2.4-GHz orthogonal frequency-division multiplexing output power of 20 dBm.
329 citations
TL;DR: In this paper, the authors presented a rigorous design of microstrip bandpass filters with a dual-passband response in parallel-coupled and vertical-stacked configurations, where the second resonant frequency can be tuned over a wide range by adjusting its structure parameters.
Abstract: This paper presents a rigorous design of microstrip bandpass filters with a dual-passband response in parallel-coupled and vertical-stacked configurations. Based on resonance characteristics of a stepped impedance resonator (SIR), the second resonant frequency can be tuned over a wide range by adjusting its structure parameters. Emphasis is placed on filter synthesis for simultaneously matching in-band response and singly loaded Q by using tapped input/output couplings for the two designated passbands. Fractional bandwidth design graphs are used to determine proper geometric parameters of each coupled stage when filter specification is given. Realizable fractional bandwidths of the two passbands for a coupled SIR structure are clearly depicted in fractional bandwidth design graphs. Several experimental filters are fabricated and measured to demonstrate the design.
324 citations
TL;DR: This paper describes a proof-of-principle test-bed that is being developed to demonstrate the Advanced Multifunction Radio Frequency Concept, a wide-band generic active array antenna architecture that has the ability to transmit and receive multiple simultaneous independent beams for radar, EW, and communication functions.
Abstract: The goal of the Advanced Multifunction Radio Frequency Concept (AMRFC) Program is to demonstrate the integration of many sorts of shipboard RF functions including radar, communications, and electronic warfare (EW) utilizing a common set of broad-band array antennas, signal and data processing, signal generation, and display hardware. The AMRFC Program was launched in response to the growing number of topside antennas on U.S. Navy ships, which have almost doubled from the ships launched in the 1980s to those launched in the 1990s. The AMRFC Program seeks to develop and demonstrate a wide-band generic active array antenna architecture that has the ability to transmit and receive multiple simultaneous independent beams for radar, EW, and communication functions. This paper describes a proof-of-principle test-bed that is being developed to demonstrate the AMRFC.
311 citations
TL;DR: A multistandard architecture for a fully-integrated CMOS receiver is proposed, likely to all be present in the "universal" terminal of the future, enabling global roaming and wireless connectivity.
Abstract: In the recent past, there has been an evolution in wireless communications toward multifunctions and multistandard mobile terminals. Reducing the number of external components to a minimum is key when the same mobile terminal has to process several different standards. Highly integrated solutions in low-cost silicon technologies are thus required. Zero-IF and low-IF receiver architectures are most suitable for a high level of integration. This paper presents a review of global system for mobile communications, universal mobile telecommunication system, Bluetooth, and wireless local area network (IEEE802.11a, b, g and HiperLAN2) standards, likely to all be present in the "universal" terminal of the future, enabling global roaming and wireless connectivity. The various standards are analyzed in order to find the optimal architecture and the building-block specifications for the receive section, with particular care to the RF front-end. State-of-the-art solutions are discussed, with emphasis on direct conversion CMOS implementations. A multistandard architecture for a fully-integrated CMOS receiver is proposed.
295 citations
TL;DR: In this article, a new technique to generate and distribute a wide-band continuously tunable millimeter-wave signal using an optical external modulator and a wavelength-fixed optical notch filter is proposed.
Abstract: A new technique to generate and distribute a wide-band continuously tunable millimeter-wave signal using an optical external modulator and a wavelength-fixed optical notch filter is proposed. The optical intensity modulator is biased to suppress the odd-order optical sidebands. The wavelength-fixed optical notch filter is then used to filter out the optical carrier. Two second-order optical sidebands are obtained at the output of the notch filter. A millimeter-wave signal that has four times the frequency of the microwave drive signal is generated by beating the two second-order optical sidebands at a photodetector. Since no tunable optical filter is used, the system is easy to implement. A system using an LiNbO/sub 3/ intensity modulator and a fiber Bragg grating filter is built. A stable and high spectral purity millimeter-wave signal tunable from 32 to 50 GHz is obtained by tuning the microwave drive signal from 8 to 12.5 GHz. The integrity of the generated millimeter-wave signal is maintained after transmission over a 25-km standard single-mode fiber. Theoretical analysis on the harmonic suppression with different modulation depths and filter attenuations is also discussed.
290 citations
TL;DR: A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported in this article.
Abstract: A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center frequency of the filter from 2.44 to 2.88 GHz (16% tuning) while achieving a 1-dB bandwidth of 400 MHz. The insertion loss varied from 5.1 dB at zero bias to 3.3 dB at full bias, while the return loss exceeded 13 dB over the range. The third-order intercept of the filter was found to be 41 dBm.
TL;DR: A two-dimensional breast model based on magnetic resonance imaging data is considered, and the focusing abilities of a TR mirror comprised of an array of receivers with a single ultra-wideband pulse excitation are examined.
Abstract: The feasibility of microwave breast cancer detection with a time-reversal (TR) algorithm is examined. This algorithm is based on the finite-difference time-domain method, and compensates for the wave decay and, therefore, is suitable for lossy media. In this paper, we consider a two-dimensional breast model based on magnetic resonance imaging data, and examine the focusing abilities of a TR mirror comprised of an array of receivers with a single ultra-wideband pulse excitation. In order to resolve small 3-mm-diameter tumors, a very short duration pulse is necessary, and this requirement may restrict the applicability of the system due to hardware limitations. We propose a way to overcome this obstacle based on the observation that the amplitude and phase information of the tumor response is sufficient to achieve focusing. The robustness of the TR algorithm with respect to breast inhomogeneities is demonstrated, and the good performance of the method suggests it is a promising technique for microwave breast cancer detection.
TL;DR: In this paper, a Doherty amplifier with uneven input drive and individual matching for the carrier and peaking cells was proposed, where higher input power is delivered to the peaking cell rather than the carrier cell for optimized linear power operation, especially for appropriate load modulation.
Abstract: We developed a Doherty amplifier with uneven input drive and optimized individual matching for the carrier and peaking cells. In the proposed amplifier, higher input power is delivered to the peaking cell rather than the carrier cell for optimized linear power operation, especially for appropriate load modulation. Both cells are matched differently to further optimize the performance. We analyzed the efficiency of the proposed amplifier as a function of the input drive ratio for the two cells. To interpret the linearity related to the load modulation and harmonic cancellation mechanisms, we simulated the third-order intermodulation amplitude and phase of each cell of the proposed amplifier. For verification, we implemented the asymmetric power amplifier with uneven drive and optimized power matching using Motorola's MRF281SR1 LDMOSFET with a 4-W peak envelope power. For a 2.14-GHz forward-link wireless code-division multiple-access signal, the measured drain efficiency of the amplifier is 40%, and the measured average output power is 33 dBm at an adjacent channel leakage ratio (ACLR) of -35 dBc, while those of the comparable class-AB amplifier are 21% and 30.6 dBm at the same ACLR level, respectively.
TL;DR: In this article, a local oscillator phase-shifting approach is introduced to implement a fully integrated 24-GHz phased-array receiver using SiGe technology, which achieves state-of-the-art performance.
Abstract: A local-oscillator phase-shifting approach is introduced to implement a fully integrated 24-GHz phased-array receiver using SiGe technology. Sixteen phases of the local oscillator are generated in one oscillator core, resulting in a raw beam-forming accuracy of 4 bits. These phases are distributed to all eight receiving paths of the array by a symmetric network. The appropriate phase for each path is selected using high-frequency analog multiplexers. The raw beam-steering resolution of the array is better than 10deg for a forward-looking angle, while the array spatial selectivity, without any amplitude correction, is better than 20 dB. The overall gain of the array is 61 dB, while the array improves the input signal-to-noise ratio by 9 dB
TL;DR: In this article, a method to design low-pass filters (LPF) having a defected ground structure (DGS) and broadened transmission-line elements is proposed, which can be applied in design N-pole LPFs for N/spl les/5.
Abstract: A method to design low-pass filters (LPF) having a defected ground structure (DGS) and broadened transmission-line elements is proposed. The previously presented technique for obtaining a three-stage LPF using DGS by Lim et al. is generalized to propose a method that can be applied in design N-pole LPFs for N/spl les/5. As an example, a five-pole LPF having a DGS is designed and measured. Accurate curve-fitting results and the successive design process to determine the required size of the DGS corresponding to the LPF prototype elements are described. The proposed LPF having a DGS, called a DGS-LPF, includes transmission-line elements with very low impedance instead of open stubs in realizing the required shunt capacitance. Therefore, open stubs, teeor cross-junction elements, and high-impedance line sections are not required for the proposed LPF, while they all have been essential in conventional LPFs. Due to the widely broadened transmission-line elements, the size of the DGS-LPF is compact.
TL;DR: In this article, the authors presented a state-of-the-art RF microelectromechanical systems wideband miniature tunable filter designed for 6.5-10 GHz frequency range.
Abstract: This paper presents a state-of-the-art RF microelectromechanical systems wide-band miniature tunable filter designed for 6.5-10-GHz frequency range. The differential filter, fabricated on a glass substrate using digital capacitor banks and microstrip lines, results in a tuning range of 44% with very fine resolution, and return loss better than 16 dB for the whole tuning range. The relative bandwidth of the filter is 5.1 /spl plusmn/ 0.4% over the tuning range and the size of the filter is 5 mm /spl times/ 4 mm. The insertion loss is 4.1 and 5.6 dB at 9.8 and 6.5 GHz, respectively, for a 1-k/spl Omega//sq fabricated bias line. The simulations show that, for a bias line with 10-k/spl Omega//sq resistance or more, the insertion loss improves to 3 dB at 9.8 GHz and 4 dB at 6.5 GHz. The measured IIP/sub 3/ level is > 45 dBm for /spl Delta/f > 500 kHz, and the filter can handle 250 mW of RF power for hot and cold switching.
TL;DR: In this paper, a coplanar-waveguide filter was proposed for the 12-18 GHz frequency range, with a tuning range of 40% with very fine resolution, and return loss better than 10 dB for the whole tuning range.
Abstract: This paper presents a state-of-the-art RF microelectromechanical systems (MEMS) wide-band tunable filter designed for the 12-18-GHz frequency range The coplanar-waveguide filter, fabricated on a glass substrate using loaded resonators with RF MEMS capacitive switches, results in a tuning range of 40% with very fine resolution, and return loss better than 10 dB for the whole tuning range The relative bandwidth of the filter is 57/spl plusmn/04% over the tuning range and the size of the filter is 8 mm/spl times/4 mm The insertion loss is 55 and 82 dB at 178 and 122 GHz, respectively, for a 2-k/spl Omega//sq bias line The loss improves to 45 and 68 dB at 178 and 122 GHz, respectively, if the bias line resistance is increased to 20 k/spl Omega//sq The measured IIP/sub 3/ level is >37 dBm for /spl Delta/f>200 kHz To our knowledge, this is the widest band planar tunable filter to date
TL;DR: In this article, a power/ground planes design for efficiently eliminating the ground bounce noise (GBN) in high-speed digital circuits is proposed by using low-period coplanar electromagnetic bandgap (LPC-EBG) structure.
Abstract: A power/ground planes design for efficiently eliminating the ground bounce noise (GBN) in high-speed digital circuits is proposed by using low-period coplanar electromagnetic bandgap (LPC-EBG) structure. Keeping solid for the ground plane and designing an LPC-EBG pattern on the power plane, the proposed structure omnidirectionally behaves highly efficiently in suppression of GBN (over 50 dB) within the broad-band frequency range (over 4 GHz). In addition, the proposed designs suppress radiated emission (or electromagnetic interference) caused by the GBN within the stopband. These extinctive behaviors of low radiation and broad-band suppression of the GBN is demonstrated numerically and experimentally. Good agreements are seen. The impact of the LPC-EBG power plane on the signal integrity for the signals referring to the power plane is investigated. Two possible solutions, differential signals and an embedded LPC-EBG power plane concept, are suggested and discussed to reduce the impact.
TL;DR: In this paper, three types of compact SIW-PS wide-band bandpass filters are proposed and investigated with simulation and experiment, with low insertion loss and sharp out-of-band characteristics observed from both simulated and measured results.
Abstract: It is known that the substrate integrated waveguide (SIW) features high-pass characteristics of the conventional waveguide, and a periodic structure (PS) generally presents bandstop characteristics. Therefore, a super-wide-band bandpass characteristic should be realized by combining some sort of PS into the SIW. In this paper, three types of compact SIW-PS wide-band bandpass filters are proposed and investigated with simulation and experiment. Performances of a super-wide bandpass, for instance, 8.5-16.5 GHz in this case study, with low insertion loss and sharp out-of-band characteristics are observed from both simulated and measured results.
TL;DR: In this paper, a new injection-locked dual opto-electronic oscillator (OEO) that uses a long optical fiber loop master oscillator to injection lock into a short-loop signal-mode slave oscillator was reported.
Abstract: We report a new injection-locked dual opto-electronic oscillator (OEO) that uses a long optical fiber loop master oscillator to injection lock into a short-loop signal-mode slave oscillator, which showed substantial improvements in reducing the phase noise and spurs compared to current state-of-the-art multiloop OEOs operating at 10 GHz. Preliminary phase-noise measurement indicated approximately 140-dB reduction of the spurious level.
TL;DR: In this article, the authors presented a new set of results concerning the use of higher/lower order modes as a means to implement bypass or cross coupling for applications in elliptic filter design.
Abstract: This paper presents a new set of results concerning the use of higher/lower order modes as a means to implement bypass or cross coupling for applications in elliptic filter design. It is shown that the signs of the coupling coefficients to produce a transmission zero (TZ) either below or above the passband are, in certain situations, reversed from the predictions of simpler existing models. In particular, the bypass coupling to higher/lower order modes must be significantly stronger than the coupling to the main resonance in order to generate TZs in the immediate vicinity of the passband. Planar (H-plane) singlets are used to illustrate the derived results. This study should provide very important guidelines in selecting the proper main and bypass couplings for sophisticated filtering structures. Example filters are designed, built, and measured to demonstrate the validity of the introduced theory.
TL;DR: In this paper, the performance of the Newton and the multiplicative regularized contrast source inversion (MR-CSI) methods in 2D geometry and gradient and MR-CSIs in 3D geometry using high-contrast, medium-size phantoms, and biological objects was evaluated and discussed based on its performance and quality of reconstructed images.
Abstract: Microwave tomography is an imaging modality based on differentiation of dielectric properties of an object. The dielectric properties of biological tissues and its functional changes have high medical significance. Biomedical applications of microwave tomography are a very complicated and challenging problem, from both technical and image reconstruction point-of-views. The high contrast in tissue dielectric properties presenting significant advantage for diagnostic purposes possesses a very challenging problem from an image-reconstruction prospective. Different imaging approaches have been developed to attack the problem, such as two-dimensional (2-D) and three-dimensional (3-D), minimization, and iteration schemes. The goal of this research is to study imaging performance of the Newton and the multiplicative regularized contrast source inversion (MR-CSI) methods in 2-D geometry and gradient and MR-CSI methods in 3-D geometry using high-contrast, medium-size phantoms, and biological objects. Experiments were conducted on phantoms and excised segment of a pig hind-leg using a 3-D microwave-tomographic system operating at frequencies of 0.9 and 2.05 GHz. Both objects being of medium size (10-15 cm) possess high dielectric contrasts. Reconstructed images were obtained using all imaging approaches. Different approaches are evaluated and discussed based on its performance and quality of reconstructed images.
TL;DR: In this paper, a bandpass filter design method for suppressing spurious responses in the stopband by choosing the constitutive resonators with the same fundamental frequency, but staggered higher order resonant frequencies is proposed.
Abstract: This paper proposes a bandpass filter design method for suppressing spurious responses in the stopband by choosing the constitutive resonators with the same fundamental frequency, but staggered higher order resonant frequencies. The design concept is demonstrated by a four-pole parallel-coupled Chebyshev bandpass filter and a compact four-pole cross-coupled elliptic-type bandpass filter. Each filter is composed of four different stepped-impedance resonators (SIRs) for which a general design guideline has been provided in order to have the same fundamental frequency and different spurious frequencies by proper adjusting the impedance and length ratios of the SIR. Being based on knowledge of the coupling coefficients and following the traditional design procedure, the resultant filter structures are simple and easy to synthesize. The measured results are in good agreement with the simulated predictions, showing that better than -30-dB rejection levels in the stopband up to 5.4f/sub 0/ and 8.2f/sub 0/ are achieved by the Chebyshev and quasi-elliptic filters, respectively.
TL;DR: This paper is aimed at assessing the effectiveness of the proposed PSO-based approach in locating, shaping, and reconstructing the dielectric parameters of unknown two-dimensional scatterers in microwave-imaging applications.
Abstract: A computational approach based on an innovative stochastic algorithm, namely, the particle swarm optimizer (PSO), is proposed for the solution of the inverse-scattering problem arising in microwave-imaging applications. The original inverse-scattering problem is reformulated in a global nonlinear optimization one by defining a suitable cost function, which is minimized through a customized PSO. In such a framework, this paper is aimed at assessing the effectiveness of the proposed approach in locating, shaping, and reconstructing the dielectric parameters of unknown two-dimensional scatterers. Such an analysis is carried out by comparing the performance of the PSO-based approach with other state-of-the-art methods (deterministic, as well as stochastic) in terms of retrieval accuracy, as well as from a computational point-of-view. Moreover, an integrated strategy (based on the combination of the PSO and the iterative multiscaling method) is proposed and analyzed to fully exploit complementary advantages of nonlinear optimization techniques and multiresolution approaches. Selected numerical experiments concerning dielectric scatterers different in shape, dimension, and dielectric profile, are performed starting from synthetic, as well as experimental inverse-scattering data.
TL;DR: In this paper, an open-structure eigenvalue problem of substrate integrated waveguide (SIW) cavity structures is investigated in detail by using a finite-difference frequency-domain method, and the quality (Q) factor of such SIW cavities is given.
Abstract: An open-structure eigenvalue problem of substrate integrated waveguide (SIW) cavity structures is investigated in detail by using a finite-difference frequency-domain method, and the quality (Q) factor of such SIW cavities is given. Based on the concept of a defected ground structure, a new class of SIW cavity bandpass filters are designed, fabricated, and measured around 5.8 GHz. With their fabrication on standard printed circuit boards, such filters present the advantages of high-Q factor, high power capacity, and small size. Simulated and measured results are presented and discussed to show promising performances of the proposed filters.
TL;DR: In this paper, a multistage Doherty power amplifier that meets wide-band code-division multiple access (WCDMA) requirements is demonstrated, and the power amplifier exhibits a power-added efficiency (PAE) of 42% at 6-dB output power backoff and 27% at 12-dB performance backoff.
Abstract: A comprehensive analysis of a multistage Doherty amplifier, which can be used to achieve higher efficiency at a lower output power level compared to the classical Doherty amplifier, is presented. Generalized design equations that explain the operation of a three-stage Doherty amplifier, which can be easily extended to an N-stage Doherty amplifier, are derived. In addition, the optimum device periphery, which minimizes AM-AM distortion for perfect Doherty amplifier operation, is analyzed. For the first time, a multistage Doherty power amplifier that meets wide-band code-division multiple-access (WCDMA) requirements is demonstrated. The designed power amplifier exhibits a power-added efficiency (PAE) of 42% at 6-dB output power backoff and 27% at 12-dB output power backoff. These PAEs are more than 2/spl times/ and 7/spl times/ better, respectively, than that of a single-stage linear power amplifier at the same output power backoff levels. The power amplifier is capable of delivering up to 33 dBm of output power, and has a maximum adjacent channel power leakage ratio of -35 and -47 dBc at 5- and 10-MHz offset, respectively. To the best of the authors' knowledge, these represent the best reported results of a Doherty amplifier for WCDMA application in the 1.95-GHz band to date.
TL;DR: In this article, the authors used a rational function model to solve the inverse problem, i.e., to convert the aperture-plane reflection coefficient to the tissue permittivity, and demonstrated that these precision probes, used with the prescribed measurement protocols and data processing techniques, provide highly accurate and reliable in vivo and ex vivo biological tissue measurements, including breast tissue spectroscopy.
Abstract: Hermetic stainless-steel open-ended coaxial probes have been designed for precision dielectric spectroscopy of biological tissue, such as breast tissue, over the 0.5-20-GHz frequency range. Robust data-processing techniques have also been developed for extracting the unknown permittivity of the tissue under test from the reflection coefficient measured with the precision probe and a vector network analyzer. The first technique, referred to as a reflection-coefficient deembedding method, converts the reflection coefficient measured at the probe's calibration plane to the desired aperture-plane reflection coefficient. The second technique uses a rational function model to solve the inverse problem, i.e., to convert the aperture-plane reflection coefficient to the tissue permittivity. The results of the characterization and validation studies demonstrate that these precision probes, used with the prescribed measurement protocols and data-processing techniques, provide highly accurate and reliable in vivo and ex vivo biological tissue measurements, including breast tissue spectroscopy.
TL;DR: In this paper, a general and direct synthesis technique of pseudoelliptic inline filters with arbitrarily placed attenuation poles (APs) at real frequencies is presented, where APs are brought about and independently controlled by dedicated resonators, which are coupled to nonresonating nodes.
Abstract: A general and direct synthesis technique of pseudoelliptic inline filters with arbitrarily placed attenuation poles (APs) (transmission zeros) at real frequencies is presented. The APs are brought about and independently controlled by dedicated resonators, which are coupled to nonresonating nodes. Simple rules to properly determine the phases of the reflection coefficients at the input and output are given. To reduce the effect of roundoff errors, especially for higher order filters, the extraction of the elements of the network is performed from the input and output simultaneously. Multiplicity and scaling properties of the solutions are discussed. Synthesis examples are presented to demonstrate the soundness of the procedure. Theoretical results are compared with measurement to demonstrate the validity of the presented theory.
TL;DR: In this article, the design principles of CMOS low-noise amplifiers (LNAs) for simultaneous input impedance and noise matching by tailoring device size for R/sub opt/=50 /spl Omega/ are introduced.
Abstract: Design principles of CMOS low-noise amplifiers (LNAs) for simultaneous input impedance and noise matching by tailoring device size for R/sub opt/=50 /spl Omega/ are introduced. It is found that R/sub opt/ close to 50 /spl Omega/ can be obtained by using small devices (110 /spl mu/m) and small currents (5 mA). Based on the proposed approach, CMOS LNAs with on-chip input and output matching networks on thin (/spl sim/20 /spl mu/m) and normal (750 /spl mu/m) substrates are implemented. It is found that the noise figure (NF) (3.0 dB) of the CMOS LNA at 5.2 GHz with 10-mW power consumption on the normal (750 /spl mu/m) substrate can be reduced to 2.17 dB after the substrate is thinned down to /spl sim/20 /spl mu/m. The reduction of NF is attributed to the suppression of substrate loss of the on-chip inductors. The input return loss (S/sub 11/) is smaller than -22 dB across the entire band of interest (5.15-5.35 GHz). An input 1-dB compression point (P/sub 1 dB/) of -8.3 dBm and an input third-order intercept point of 0.8 dBm were also obtained for the LNA on the thin substrate.
TL;DR: In this article, a new differential surface admittance concept is proposed to replace the conductor by equivalent electric surface currents and to replace material of the conductors by the material of a background medium the conductor is embedded in.
Abstract: An important issue in high-frequency signal integrity prediction is the modeling of the skin effect of thick conductors. A new differential surface admittance concept is put forward allowing to replace the conductor by equivalent electric surface currents and to replace the material of the conductor by the material of the background medium the conductor is embedded in. This new concept is studied in detail for the two-dimensional TM case starting from the Dirichlet eigenfunctions of the cross section. Detailed expressions are derived for the important practical case of a rectangular cross section. Next, the differential surface admittance operator is exploited to determine the resistance and inductance matrices of a set of multiconductor lines. A first set of numerical results provides the reader with some insight into the behavior of the surface admittance matrix. A second set of results demonstrates the correctness and versatility of the new approach to determine inductance and resistance matrices.