Showing papers in "IEEE Microwave and Guided Wave Letters in 1998"
TL;DR: In this paper, a 2D photonic bandgap (PBG) structure for microstrip lines is proposed, in which a periodic 2D pattern consisting of circles is etched in the ground plane of microstrip line.
Abstract: A new two-dimensional (2-D) photonic bandgap (PBG) structure for microstrip lines is proposed, in which a periodic 2-D pattern consisting of circles is etched in the ground plane of microstrip line. No drilling through the substrate is required. Three PBG circuits were fabricated with different circle radii to determine the optimum dimensions, as well as a PBG circuit with the compensated right-angle microstrip bend. Measurements show that deep and wide stopbands can be achieved using this method.
706 citations
TL;DR: In this paper, the construction and performance of metal membrane radio frequency MEMS switches at microwave and millimeter-wave frequencies was described. But the authors focused on the performance of the switches in terms of on-off capacitance ratio.
Abstract: 'This letter details the construction and performance of metal membrane radio frequency MEMS switches at microwave and millimeter-wave frequencies. These shunt switches possess a movable metal membrane which pulls down onto a metal/dielectric sandwich to form a capacitive switch. These switches exhibit low loss (<0.25 dB at 35 GHz) with good isolation (35 dB at 35 GHz). These devices possess on-off capacitance ratios in the range of 80-110 with a cutoff frequency (figure of merit) in excess of 9000 GHz, significantly better than that achievable with electronic switching devices.
474 citations
TL;DR: Based on the (m, N, q)-regular Fourier matrix, a new algorithm is proposed for fast Fourier transform (FFT) of nonuniform (unequally spaced) data with accuracy much better than previously reported results with the same computation complexity.
Abstract: Based on the (m, N, q)-regular Fourier matrix, a new algorithm is proposed for fast Fourier transform (FFT) of nonuniform (unequally spaced) data. Numerical results show that the accuracy of this algorithm is much better than previously reported results with the same computation complexity of O(N log/sub 2/ N). Numerical examples are shown for the applications in computational electromagnetics.
251 citations
TL;DR: In this article, two AB GaAs field effect transistor (FET) power amplifiers have been designed and fabricated in the 4.4-4.8 GHz range, and a dielectric PBG line was incorporated in the design to tune the second harmonic.
Abstract: Two class AB GaAs field-effect transistor (FET) power amplifiers have been designed and fabricated in the 4.4-4.8 GHz range. In the first case, a dielectric PBG line was incorporated in the design to tune the second harmonic. In the second case, a 50-/spl Omega/ line is used with no harmonic tuning. The PBG structure allows broad-band harmonic tuning and is inexpensive to fabricate. A 5% improvement in power-added efficiency was achieved at the design frequency of 4.5 GHz, in both simulation and measurement.
250 citations
TL;DR: The perfectly matched layer (PML) constitutive tensors that match more general linear media presenting bianisotropic and dispersive behavior are obtained for single interface problems and for two-dimensional and three-dimensional (3D) corner regions as mentioned in this paper.
Abstract: The perfectly matched layer (PML) constitutive tensors that match more general linear media presenting bianisotropic and dispersive behavior are obtained for single interface problems and for two-dimensional (2-D) and three-dimensional (3-D) corner regions. The derivation is based on the analytic continuation of Maxwell's equations to a complex variables domain. The formulation is Maxwellian so that it is equally applicable to the finite-difference time-domain (FDTD) or finite-element (FEM) methods. It recovers, as special cases, previous anisotropic media formulations, and dispersive media formulations.
223 citations
TL;DR: The application of photonic bandgap structures (PBG's) as substrates in microstrip circuits has been investigated in this paper, where the effects of substrate thickness, microstrip transmission line location, and length of the PBG structure were studied using a finite-difference time-domain simulation and experimental measurement.
Abstract: The application of photonic bandgap structures (PBG's) as substrates in microstrip circuits has been investigated. The effects of substrate thickness, microstrip transmission line location, and length of the PBG structure were studied using a finite-difference time-domain (FDTD) simulation and experimental measurement. A low-pass filter with a very wide high-frequency rejection bandwidth was constructed from a serial connection of many different PBG structures.
199 citations
TL;DR: In this paper, a bandpass delta-sigma modulator is used to produce a two-level digital signal representing an analog radio frequency (RF) input, and a switchingmode amplifier and bandpass filter are used to amplify the signal and remove unwanted spectral components.
Abstract: A novel amplifier configuration is described, in which a bandpass delta-sigma modulator is used to produce a two-level (digital) signal representing an analog radio frequency (RF) input. Subsequently, a switching-mode amplifier and bandpass filter are used to amplify the signal and remove unwanted spectral components. This configuration has the potential of achieving high efficiency (typical of switching mode amplifiers) together with high linearity. A simulated implementation with GaAs heterojunction bipolar transistors (HBT) is shown.
158 citations
TL;DR: In this article, a low-loss slow-wave microstrip line using a periodic structure in the ground plane is presented, which is realized with metal pads etched with thin lines to form a distributed LC network.
Abstract: A low-loss slow-wave microstrip line using a periodic structure in the ground plane is presented. The periodic structure is realized with metal pads etched in the ground plane connected by thin lines to form a distributed LC network. The slow-wave factor is demonstrated to be 1.2-2.4 times larger than that of conventional microstrip lines over a wide frequency range. Due to the unique design of the structure, low insertion loss comparable to conventional microstrips has been achieved. The proposed structure is easier to fabricate than other slow-wave devices which require multilayer substrates or very fine features.
126 citations
TL;DR: In this article, an efficient method for analyzing cavity structures by using the fast Fourier transform (FFT)/Pade technique, in combination with the finite-difference time-domain (FDTD) method, is presented.
Abstract: An efficient method for analyzing cavity structures by using the fast Fourier transform (FFT)/Pade technique, in combination with the finite-difference time-domain (FDTD) method, is presented. Without sacrificing the accuracy of the results, this new method significantly reduces the computational time compared to that needed where the conventional FFT algorithm is used. The usefulness of this approach is demonstrated by modeling a lossy cavity and computing its resonant frequencies as well as Q.
105 citations
TL;DR: In this article, a capacitively loaded coplanar waveguide (CPW) resonator has been used to achieve a slow-wave effect without occupying extra surface area and it has a good performance as compared with the conventional halfwavelength CPW resonator.
Abstract: A capacitively loaded coplanar waveguide (CPW) resonator has been studied. It has been shown that the proposed resonator can be used to achieve a slow-wave effect without occupying extra surface area and it has a good performance as compared with the conventional half-wavelength CPW resonator. Furthermore, dispersive effects have been increased with the number of slots in periodically loaded structures.
92 citations
TL;DR: In this paper, a hybrid finite element finite-difference time-domain (FE/FDTD) technique for solving complex electromagnetic problems is presented, which combines the computational simplicity of the structured FDTD scheme with the versatility as well as flexibility of the finite element method (FEM) and enables us to accurately model curved geometries and those with fine features.
Abstract: A hybrid finite element finite-difference time-domain (FE/FDTD) technique for solving complex electromagnetic problems is presented. The method combines the computational simplicity of the structured FDTD scheme with the versatility as well as flexibility of the finite-element method (FEM) and enables us to accurately model curved geometries and those with fine features. Numerical results that illustrate the accuracy of the method are included.
TL;DR: In this paper, a two-pole thin-film K-band tunable bandpass filter on a lanthanum aluminate substrate has been presented, achieving a center frequency of 19 GHz and a 4% bandwidth.
Abstract: We report on a gold/strontium titanate (Au-SrTiO/sub 3/) thin-film K-band tunable bandpass filter on a lanthanum aluminate substrate. The two-pole filter has a center frequency of 19 GHz and a 4% bandwidth. Tunability is achieved through the nonlinear temperature dependence and the DC electric field dependence of the relative dielectric constant of SrTiO/sub 3/. A center frequency shift of 0.85 GHz was obtained at 400 V DC bias and 77 K without degrading the insertion loss of the filter.
TL;DR: In this paper, an efficient method is developed for the rapid and accurate calculation of the potential Green's function in the rectangular cavity, which is based on the Ewald sum technique and converts the slowly convergent cavity green's function into the sum of two exponentially convergent series, achieving fast convergence with only a small number of terms in the calculation.
Abstract: An efficient method is developed for the rapid and accurate calculation of the potential Green's function in the rectangular cavity. The proposed method is based on the Ewald sum technique and converts the slowly convergent cavity Green's function into the sum of two exponentially convergent series. The transformed series achieves fast convergence with only a small number of terms in the calculation.
TL;DR: In this article, a set of hierarchical mixed-order TVFEs up to and including order 2.5 was proposed for a tetrahedral element, which can be formulated for higher orders than 2.
Abstract: Tangential vector finite elements (TVFEs) overcome most of the shortcomings of node-based finite elements for electromagnetic simulations. Hierarchical TVFEs are of considerable practical interest since they allow use of effective selective field expansions where different order TVFEs are combined within a computational domain. For a tetrahedral element, this letter proposes a set of hierarchical mixed-order TVFEs up to and including order 2.5 that differ from previously presented TVFEs. The hierarchical mixed-order TVFEs are constructed as the three-dimensional equivalent of hierarchical mixed-order TVFEs for a triangular element. They can be formulated for higher orders than 2.5, and the generalization to curved tetrahedral elements is straightforward.
TL;DR: In this article, the equivalence theorem is employed to separate the original problem into two subproblems: (1) the region containing the wires, which is analyzed by using the MoMTD, and (2) the dielectric zone that is modeled with the FDTD.
Abstract: This letter presents a new hybrid method that efficiently combines two versatile numerical techniques, viz., the finite difference time domain (FDTD) and the method of moments in the time domain (MoMTD). The hybrid method is applicable to complex geometries comprising arbitrary thin-wire and inhomogeneous dielectric structures. It employs the equivalence theorem to separate the original problem into two subproblems: (1) the region containing the wires, which is analyzed by using the MoMTD, and (2) the dielectric zone that is modeled with the FDTD. The application of the method is illustrated by analyzing two canonical problems involving thin wires and inhomogeneous media.
TL;DR: In this paper, a two-stage monolithic microwave integrated circuit (MMIC) power amplifier with 0.15/spl mu/m gate length and 1.28mm output periphery fabricated using this process has demonstrated an output power of 427 mW with 19% power-added efficiency at 95 GHz.
Abstract: We have established a state-of-the-art InGaAs-InAlAs-InP HEMT MMIC fabrication process for millimeter-wave high-power applications. A two-stage monolithic microwave integrated circuit (MMIC) power amplifier with 0.15-/spl mu/m gate length and 1.28-mm output periphery fabricated using this process has demonstrated an output power of 427 mW with 19% power-added efficiency at 95 GHz. To our knowledge, this is the highest output power ever reported at this frequency for any solid-state MMIC amplifier.
TL;DR: In this paper, a fully integrated 19 GHz CMOS low-noise amplifer (LNA) was implemented in a 08 /spl mu/m CMOS technology for lownoise performance, the amplifier employs high-quality spiral inductors with a duality factor of 85-125, and device layout and bias condition of the active devices were optimized for low noise conditions
Abstract: A fully integrated 19 GHz CMOS low-noise amplifer (LNA) has been implemented in a 08 /spl mu/m CMOS technology For low-noise performance, the amplifier employs high-quality spiral inductors with a duality factor of 85-125, and device layout and bias condition of the active devices were optimized for low-noise conditions This amplifier showed a noise figure of 28 dB with a forward gain of 15 dB at current consumption of 15 mA To the authors' knowledge, this represents the lowest noise figure reported to date for a fully integrated CMOS LNA operating at 19 GHz
TL;DR: In this paper, the authors showed that the error due to the one-cell gap model is strongly dependent on the cell size, and presented an improved FDTD model which assumes an infinitesimally narrow feeding gap.
Abstract: In calculations using the finite-difference time-domain (FDTD) method, the feeding gap of a thin-wire antenna is often modeled by a so-called "one-cell gap" which lets the feeding gap to be one interval of Yee's lattice. This is often inconsistent with the actual situation and it causes error in FDTD calculation results. This work shows that the error due to the one-cell gap model is strongly dependent on the cell size, and we present an improved FDTD model which assumes an infinitesimally narrow feeding gap. We show that the antenna input impedance calculated with the new gap model is barely affected by the cell size and agrees well with the method of moments (MoM) calculation results for an infinitesimal gap. Furthermore, we clarify the dependence of error of a one-cell gap on the cell size on the basis of the proposed model.
TL;DR: In this paper, two different extensions of the FDTD method for the treatment of lossy dielectrics are considered: the time average (TA) and the time forward (TF) difference schemes.
Abstract: Two different extensions of the finite-difference time-domain (FDTD) method for the treatment of lossy dielectrics are considered: the time-average (TA) and the time-forward (TF) difference schemes. An analytical study of the stability properties and numerical dispersion of these schemes is presented. The stability analysis is based on the Von Neumann (Fourier series) method, while the numerical dispersion properties are established in terms of the numerical permittivity of discrete lossy dielectrics. The analytical stability limits are compared with those obtained numerically in previous works. The accuracy of the two schemes is compared by computing the reflection coefficient of a lossy dielectric slab.
TL;DR: In this article, a new method for reducing the substrate-related losses of integrated spiral inductors for Si RF ICs was proposed, which increased the quality factor from 5.3 to 6.0 at 3.5 GHz at an 1.8 nH inductor.
Abstract: The authors introduce a new method for reducing the substrate-related losses of integrated spiral inductors for Si RF ICs. Measurement based equivalent circuit parameters are demonstrated. Using our method the quality factor increased from 5.3 to 6.0 at 3.5 GHz at an 1.8 nH inductor.
TL;DR: In this paper, a new version of the PML that allows a substantial absorption of evanescent modes is presented. But the absorption is not achieved by usual perfectly matched layers (PMLs) terminating waveguiding structures.
Abstract: As emphasized by several authors in literature, the evanescent modes are not absorbed by usual perfectly matched layers (PMLs) terminating waveguiding structures. The purpose of this work is to present a new version of the PML that allows a substantial absorption of such waves to be achieved.
TL;DR: In this paper, a similar approach is proposed to model both reflection and transmission when confronted with a thin layer of good, but not perfectly, conducting material, where the reflection at materials is taken into account; the transmission through very thin layers is not considered.
Abstract: In recent papers the surface impedance condition is proposed to incorporate the effect of high conductivity of a material. This condition only takes the reflection at materials into account; the transmission through very thin layers is not considered. In this work, we introduce a similar approach to model both reflection and transmission when confronted with a thin layer of good, but not perfectly, conducting material.
TL;DR: In this article, the authors describe a cavity structure which can be used as the basic building block for the computer-aided design (CAD) of triple-mode filters in rectangular waveguide.
Abstract: In this paper describe a very simple cavity structure which can be used as the basic building block for the computer-aided design (CAD) of triple-mode filters in rectangular waveguide. The input output ports are standard rectangular waveguides with a common longitudinal axis. The proposed configuration is geometrically simple and exhibits the very important feature of being amenable to a rigorous electromagnetic simulation. As an application example, a three-pole filter is demonstrated thereby fully validating the configuration proposed.
TL;DR: In this article, the authors present the results for a 44 GHz stepped attenuator implemented in high electron mobility transistor (HEMT) MMIC technology with good phase flatness (14.5 dB) over the attenuation range.
Abstract: Radio frequency (RF) subsystems for emerging millimeter-wave applications require monolithic microwave integrated circuit (MMIC) attenuators with constant phase over the attenuation range. In this work, we present the results for a 44 GHz stepped attenuator implemented in high electron mobility transistor (HEMT) MMIC technology. Use of a switched-path topology provides a high attenuation range (>30 dB) with good phase flatness ( 14.5 dB) over the attenuation range. The same design topology should be well suited for other frequencies throughout the upper microwave and lower millimeter-wave range.
TL;DR: In this paper, the authors describe the design, simulation, fabrication, and performance of a 96 GHz ortho-mode transducer (OMT) for the Polatron-a bolometric receiver with polarization capability.
Abstract: We describe the design, simulation, fabrication, and performance of a 96-GHz ortho-mode transducer (OMT) to be used for the Polatron-a bolometric receiver with polarization capability. The OMT has low loss, good isolation, and moderately broad bandwidth, and its performance closely resembles simulation results.
TL;DR: In this article, a correction of the finite-difference (FD) methods employing Yee's mesh, improving the accuracy when conductive edge corners are present in the analyzed structure, is presented.
Abstract: The authors present a correction of the finite-difference (FD) methods employing Yee's mesh, improving the accuracy when conductive edge corners are present in the analyzed structure. The algorithm allows the wedge to be arbitrarily located with respect to the grid points and yields significant error reduction.
TL;DR: In this paper, the authors revisited and discussed the characteristic impedance and its definition for microstrip line with a self-calibrated three-dimensional (3D) method of moments (MoM).
Abstract: Characteristic impedance and its definition are revisited and discussed for microstrip line with a self-calibrated three-dimensional (3-D) method of moments (MoM). This 3-D MoM accommodates a scheme called short-open calibration (SOC) so that potential parasitic effects brought by the impressed voltage excitation and other relevant factors can be effectively removed. In this way, the characteristic impedance can be accurately defined through a relationship between equivalent voltage and current on the two sides of a microstrip line having a finite length. Simulated results are compared with the Jansen's two-dimensional (2-D) and Rautio's 3-D definition.
TL;DR: In this article, a 2-stage 80-nm gate length InGaAs/InAlAs/INP HEMT MMIC balanced amplifier has a measured on-wafer peak gain of 7.2 dB at 190 GHz and greater than 5 dB gain from 170 to 194 GHz.
Abstract: We present the highest frequency performance of any solid-state monolithic microwave integrated circuit (MMIC) amplifier. A 2-stage 80-nm gate length InGaAs/InAlAs/InP HEMT MMIC balanced amplifier has a measured on-wafer peak gain of 7.2 dB at 190 GHz and greater than 5 dB gain from 170 to 194 GHz. The circuit was fabricated using a pseudomorphic 20-nm In/sub 0.65/Ga/sub 0.35/As channel HEMT structure grown on a 3-in InP substrate by MBE. Based on the measured circuit results, the intrinsic exhibits an F/sub max/ greater than 400 GHz.
TL;DR: In this article, a technique based on the application of the genetic algorithm (GA) for extracting the equivalent circuits-from measured or computed S-parameters-that can be inserted into SPICE simulations is introduced.
Abstract: This letter introduces a new technique based on the application of the genetic algorithm (GA) for extracting the equivalent circuits-from measured or computed S-parameters-that can be inserted into SPICE simulations. The GA is a robust optimization tool that is shown to yield excellent results for discontinuities in microstrip lines, for instance a right-angled bend, and for microwave circuits, e.g., planar inductors and parallel plate capacitors.
TL;DR: In this paper, a new linearization technique is presented that allows a more efficient operation of these linear amplifiers by combining both the advantage of the transparent nature of feed-forward linearization with the efficiency of feedback linearization.
Abstract: Efficient use of the frequency spectrum necessitates the use of modulation formats such as /spl pi//4-DQPSK, which requires linear amplification to minimize spectral regrowth. A new linearization technique is presented that allows a more efficient operation of these linear amplifiers by combining both the advantage of the transparent nature of feed-forward linearization with the efficiency of feedback linearization. The method of convolution is used to analyze the amplifier characteristics and to determine how linearization can be achieved. This method is verified experimentally and proves that by careful use of the second harmonic component, a new method of linearization has been realized.