Showing papers on "Coplanar waveguide published in 2002"

Miniaturized Wilkinson power dividers utilizing capacitive loading

Abstract: The authors report the miniaturization of a planar Wilkinson power divider by capacitive loading of the quarter wave transmission lines employed in conventional Wilkinson power dividers. Reduction of the transmission line segments from /spl lambda//4 to between /spl lambda//5 and /spl lambda//12 are reported here. The input and output lines at the three ports and the lines comprising the divider itself are coplanar waveguide (CPW) and asymmetric coplanar stripline (ACPS), respectively. The 10 GHz power dividers are fabricated on high resistivity silicon (HRS) and alumina wafers. These miniaturized dividers are 74% smaller than conventional Wilkinson power dividers, and have a return loss better than +30 dB and an insertion loss less than 0.55 dB. Design equations and a discussion about the effect of parasitic reactance on the isolation are presented for the first time.

Design Consideration and Performance Analysis of Substrate Integrated Waveguide Components

Abstract: This paper presents a new design scheme and measurement results of circuit discontinuities on the basis of the recently proposed substrate integrated waveguide technology. Design considerations are discussed with respect to H-plane step, post resonator, 90° bend and 90° curvature, which are analyzed using an equivalent rectangular waveguide model. Results show a good agreement between design predictions and practical measurements. Loss properties of the discontinuities are also examined. It is demonstrated that the radiation loss of the new substrate integrated waveguide is smaller as compared to dielectric and conductor losses.

Optical junction apparatus and methods employing optical power transverse-transfer

Abstract: An optical apparatus comprises an optical device fabricated on a substrate, an external-transfer optical waveguide fabricated on the substrate and/or on the optical device, and a transmission optical waveguide. The optical device and/or the external-transfer waveguide are adapted for and positioned for transfer of optical power therebetween (end-transfer or transverse-transfer). The external-transfer waveguide and/or the transmission waveguide are adapted for transverse-transfer of optical power therebetween (mode-interference-coupled or adiabatic). The transmission waveguide is initially provided as a component mechanically separate from the substrate, device, and external-transfer waveguide. Assembly of the transmission waveguide with the substrate, device, and/or external-transfer waveguide results in relative positioning of the external-transfer waveguide and the transmission waveguide for enabling transverse-transfer of optical power therebetween. Optical power transfer between the device and the transmission waveguide through the external-transfer waveguide is thereby enabled. The transmission waveguide may preferably comprise a planar waveguide on a waveguide substrate.

A spiral-shaped defected ground structure for coplanar waveguide

Abstract: The authors present a spiral-shaped defected ground structure for coplanar waveguides (DGSCPW), which can be used as a kind of periodic structure for a planar transmission line. The proposed spiral-DGSCPW adopts spiral-shaped defects on both ground planes of CPW. Due to the spiral-shaped defects, the equivalent shunt inductance and slow-wave effects increase more rapidly than the standard CPW or CPW lines combined with the conventional PBG. The modeling and analysis to extract the equivalent circuit, increased slow-wave factor, and simulated and measured performances are presented.

Coplanar-waveguide-fed slot-coupled rectangular dielectric resonator antenna

Abstract: A novel coupling scheme to a rectangular dielectric resonator antenna is proposed and investigated. In particular, coupling to the resonator is achieved through a narrow slot at the end of a coplanar waveguide (CPW). The objectives of this design are to maximize the coupling, match the dielectric resonator to the CPW feed line, achieve resonance at the desired frequency, obtain linear polarization with low cross polarization components, and minimize back radiation without using a back conductor. An approximate and quick design approach is given followed by more accurate design and analysis using commercial software. The antenna was fabricated and tested. Measurements match well with simulation results.

Low-Cost and High-Q Millimeter-Wave Resonator Using Substrate Integrated Waveguide Technique

Abstract: A substrate integrated waveguide (SIW) cavity directly coupled to a planar circuit, i.e. microstrip line or coplanar waveguide, is presented. Different coupling topologies and coupling probes are discussed. Empirical equations to predict the resonance frequencies of the cavity are provided. A temperature stability coupling topology were fabricated and measured. Finally, as an example of potential applications, a filter using two SIW cavities was designed and measured.

Flexible interconnect cable with high frequency electrical transmission line

Abstract: A high speed flexible interconnect cable includes a number of conductive layers and a number of dielectric layers. Conductive signal traces, located on the conductive layers, combine with the dielectric layers to form one or more high speed electrical transmission line structures. The transmission line structure may be realized as a grounded coplanar waveguide structure, a microstrip structure, a stripline structure, or the like. The cable can be coupled to destination components using a variety of connection techniques, e.g., direct bonding to a circuit substrate, direct soldering to a flip chip, mechanical attachment to a component, or integration with a circuit substrate. The cable can also be terminated with any number of known or standardized connector packages, e.g., SMA, GPPO, or V connectors.

Design of defected ground structures for harmonic control of active microstrip antenna

Abstract: Photonic bandgap (PBG) structures are usually periodic structures in which propagation of a certain band of frequencies is prohibited. PBG structures for microwave frequencies are applied in planar circuits such as microstrip line and CPW (coplanar waveguide). In this case, they are more frequently termed defected ground structures (DGS). Most of the research performed on DGS has been based on the equivalent circuit consisting of lumped elements, L and C, extracted from EM simulations (see D. Ahn et al., IEEE MTT, vol.49, 2001). In addition, we also consider radiation effects by including resistance, R, in the equivalent circuit. The general 1D periodic structures with N unit cells are analyzed using an ABCD matrix formulation. The effects of the RLC elements of the unit cell, the spacing between the unit cells, and the cell number, N, are investigated in detail. For a design example, a simple 1D DGS with N=2 is designed for harmonic control through a modeling using transmission line theory. This 1D DGS with N=2 is much simpler than the one proposed by Y. Horii and M. Tsutsmi (see IEEE MGWL, vol.9, no.1. p.1895-8, 1999). The proposed approach enables us to design the required DGS quite easily and quickly.

High-Q millimeter-wave MEMS varactors: extended tuning range and discrete-position designs

Abstract: This paper presents the design, fabrication and measurement of two high-Q micro-electro-mechanical (MEMS) varactors suitable for 20-60 GHz applications. The varactors are composed of a movable bridge placed in a shunt configuration on a coplanar waveguide line. The first design is an extended tuning range varactor showing a capacitance ratio of 1.46. The second design demonstrates a discrete-position varactor with a capacitance ratio of 1.90. Both designs result in a tuning voltage of 18-25 V and an excellent quality factor of 95-100 at 34 GHz (C=80 fF). The very high resonant frequency of the varactors makes them suitable for applications at microwave and millimeter-wave frequencies.

Radio frequency module and method for manufacturing the same

Abstract: A rectangular penetration hole is formed opening in the opposite two main surfaces of a first dielectric substrate Conductors for grounding are respectively formed on the main surfaces, to cover the openings of the penetration hole A conductor layer is formed on opposite inner walls in the penetration hole of the dielectric substrate A waveguide is structured by a space surrounded by the conductors and the conductor layers The waveguide is magnetically coupled with an input/output line on a second dielectric substrate through a coupling slot Because a waveguide has walls made continuous in the dielectric substrate, a low-loss waveguide can be realized Hence, a high-performance radio frequency module can be realized

A DC-contact MEMS shunt switch

Abstract: This paper presents the design, fabrication, and performance of a metal-to-metal contact micro-electro-mechanical (MEMS) shunt switch. The switch is composed of a fixed-fixed metal beam with two pull-down electrodes and a central DC-contact area. The switch is placed in an in-line configuration in a coplanar waveguide transmission line. This topology results in a compact DC-contact shunt switch and high isolation at 0.1-18 GHz. The isolation at MM-wave frequencies is limited by the inductance to ground and is -20 dB at 18 GHz. The application areas are in wireless communications and high-isolation switching networks for satellite systems.

High frequency signal transmission from the surface of a circuit substrate to a flexible interconnect cable

Abstract: A high speed flexible interconnect cable includes a number of conductive layers and a number of dielectric layers. Conductive signal traces, located on the conductive layers, combine with the dielectric layers to form one or more high speed electrical transmission line structures. The transmission line structure may be realized as a grounded coplanar waveguide structure, a microstrip structure, a stripline structure, or the like. The cable can be coupled to destination components using a variety of connection techniques, e.g., direct bonding to a circuit substrate, direct soldering to a flip chip, mechanical attachment to a component, or integration with a circuit substrate. The cable can also be terminated with any number of known or standardized connector packages, e.g., SMA, GPPO, or V connectors.

Propagation characteristics of finite-width conductor-backed coplanar waveguides with periodic electromagnetic bandgap cells

Abstract: Wave propagation along the finite-width conductor-backed coplanar waveguide (FW-CBCPW) with periodically loaded one-dimensional electromagnetic bandgap (EBG) cells proposed earlier by the authors is investigated theoretically and experimentally in this paper. The full-wave simulation in conjunction with Floquet's theorem is employed to find the dispersion diagram for characterizing the guided and leaky waves over a wide frequency range. For examining the guided-wave mode, the equivalent-circuit model is established to obtain the analytical formula of the Bloch impedance. The remarkable slow-wave factor 1.9-2.9 times higher than that of a conventional FW-CBCPW is presented. When operating frequency is sufficiently high, the leaky-wave mode is emitted so that the structure radiates in the backward direction. Good agreement among the results of the full-wave simulation, equivalent-circuit model, published data, and measurement supports the usefulness of the proposed full-wave simulation and also validates the analytical formula. By properly adjusting the circuit configuration, the periodic EBG structure with controllable propagation characteristics, which include the bandgap zone, the slow-wave factor, and the Bloch impedance for the guided wave, as well as the radiation main beam for the leaky wave, may be achieved.

Coplanar waveguide biosensor for detecting molecular or cellular events

Abstract: A coplanar waveguide biosensor and methods of use include a coplanar waveguide transmission line and a sample containment structure. The coplanar waveguide transmission line is operable to support the propagation of an electromagnetic signal and includes a signal line and one or more spaced apart ground elements. The signal line is configured to conduct a time-varying voltage, and the one or more ground elements are configured to maintain a time-invariant voltage, a detection region being formed between a portion of the signal line and a portion of at least one of the one or more ground elements. Detection methods are improved through the enhancement of the electric field in the detection region via impedance discontinuities in the signal line and ground elements. The sample containment structure intersects the detection region of the coplanar waveguide transmission line and includes a cavity configured to hold 1 ml or less of sample solution within the detection region.

High power monolithic AlGaN/GaN HEMT oscillator

Abstract: A monolithic X-band oscillator based on an AlGaN/GaN high electron mobility transistor (HEMT) has been designed, fabricated, and characterized. A common-gate HEMT with 1.5 mm of gate width in conjunction with inductive feedback is used to generate negative resistance. A high Q resonator is implemented with a short-circuit low-loss coplanar waveguide transmission line. The oscillator delivers 1.7 W at 9.556 GHz into 50-/spl Omega/ load when biased at V/sub ds/=30 V and V/sub gs/=-5 V, with dc-to-RF efficiency of 16%. Phase noise was estimated to be -87 dBc/Hz at 100-kHz offset. Low-frequency noise, pushing and pulling figures, and time-domain characterization have been performed. Experimental results show great promise for AlGaN/GaN HEMT MMIC technology to be used in future high-power microwave source applications.

40-GHz coplanar waveguide bandpass filters on silicon substrate

Abstract: We report a very simple process to fabricate high performance filter on Si at 40 GHz using proton implantation. The filter has only -3.4-dB loss at peak transmission of 40 GHz with a broad 9-GHz bandwidth. In sharp contrast, the filter on 1.5-/spl mu/m SiO/sub 2/ isolated Si has much worse transmission and reflection loss. This is the first demonstration of high performance filter at the millimeter-wave regime on Si with process compatible with current VLSI technology.

A vertically periodic defected ground structure and its application in reducing the size of microwave circuits

Abstract: The microstrip and coplanar waveguide transmission lines combined by a vertically periodic defected ground structure (VPDGS) are proposed. The slow-wave effect, equivalent circuit, and the performances are shown. As an application example, VPDGS is adopted in the matching networks of an amplifier for size-reduction. Two series microstrip lines in input and output matching networks of the amplifier are reduced to 38.5% and 44.4% of the original lengths, respectively, due to the increased slow-wave effects, while the amplifier performances are preserved.

Coplanar integrated optical waveguide electro-optical modulator

Abstract: A coplanar integrated optical waveguide electro-optical modulator comprises a substrate ( 1 ) of an electro-optic material, at least two optical waveguides ( 41, 42 ) integrated in the substrate in correspondence of a surface ( 71 ) thereof, and an electrode system ( 80, 90, 100; 80, 90, 900; 12 - 15; 120, 130, 140, 150, 160, 170 ) arranged on the surface for applying a modulating electric field to the waveguides suitable for causing a modulation of a refractive index of the two waveguides in a device modulation region ( 50 ) The waveguides are formed, for at least a section thereof ( 411, 421 ) in the device modulation region, in respective substrate regions ( 61, 62 ) which have electro-optic coefficients of opposite sign along an axis transversal to the waveguide sections, so that a modulating electric field of same direction and orientation in the waveguide sections causes refractive index modulations of opposite sign in the waveguide sections Chirp-free coplanar waveguide modulators and single-drive double coplanar strip modulators can thus be obtained

Ultra-wideband (from DC to 110 GHz) CPW to CPS transition

Abstract: A new ultra-wideband, low-loss and small-size coplanar waveguide (CPW) to coplanar strip (CPS) transition which can be used from DC to 110 GHz is presented. The proposed transition connects CPW with CPS by the reformed air-bridge. Two ground planes of CPW are tied at their ends by a line and the centre of the line is connected to the ground strip of CPS by another line. Owing to the symmetry of the proposed structure, the currents of two ground planes of CPW are combined with the same phase and transferred to the ground strip of CPS. With height of 3 /spl mu/m, the signal line of CPW passes over two connecting lines and is connected to the signal strip of CPS. For the back-to-back transition structure, insertion loss 15 dB are obtained from 0.5 to 110 GHz.

Broadband thermoelectric microwave power sensors using GaAs foundry process

Abstract: The paper presents the first demonstration of an integrated MMIC compatible thermoelectric microwave power sensor for frequencies between 1 to 20 GHz using a standard GaAs foundry process. Two different types of sensors are described: an insertion sensor for the measurement of transmitted power through a coplanar waveguide and a termination sensor which measures the power dissipated in a 50 /spl Omega/ load. The transmission sensor has a very low insertion loss of less than 0.3 dB and VSWR lower than 1.2. Due to their low time constant of approximately 1 /spl mu/s, these sensors are well suited for pulsed applications. The sensor exhibits an inherent linearity for large power levels and does not require any bias.

Novel transition between different configurations of planar transmission lines

Abstract: New designs of coplanar waveguide (CPW)-microstrip, CPW-stripline, conductor backed CPW (CBCPW)-microstrip, and CBCPW-stripline transitions are presented. Simulation using the high frequency structures simulator (HFSS) shows that the return loss of the CPW-microstrip transition is less than -25 dB up to 11 GHz. Similarly is the CPW-stripline transition. In the case of two back to back CBCPW-stripline transitions, the return loss is less than -22 dB up to 9 GHz. Experimentally, the S/sub 11/ of two back to back CBCPW-microstrip transitions on an alumina substrate is less than -15 dB up to 25 GHz.

Coplanar-waveguide-based terahertz hot-electron-bolometer mixers mproved embedding circuit description

Abstract: Series-fed coplanar-waveguide embedding circuits have been recently developed for terahertz mixers using, in particular, superconducting devices as sensors. Although these mixers show promising performance, they usually also show a considerable downward shift in the resonating frequency when compared with calculations using simplified models. This effect is basically caused by parasitics due to the extremely small details (in terms of wavelength) of the device and to the connection of the remaining circuitry (i.e., RF filter). In this paper, we present an improved equivalent-network model of such devices that agrees with measured results. We first propose a method to calculate the characteristic impedance and propagation constant of the coplanar waveguide, etched between two semi-infinite media, which connect the receiving slot antennas to the superconducting device. In the formulation, we take into account, for the first time, the radiation power leakage. We then describe the procedure to calculate the reactances due to the detailed geometry of the mixer device and circuit and we correct the input impedance, calculated with a commonly used simplified network. Finally, by comparing our results with a complete set of measured data, for seven mixers in the range between 500 GHz-3 THz, we analyze the features of our model and propose further improvements. Useful guidelines for designing terahertz mixer circuits are also given.

A CPW T-resonator technique for electrical characterization of microwave substrates

Abstract: An impedance independent method is proposed using a finite ground coplanar waveguide (CPW) T-resonator to electrically characterize microwave materials. Silicon-based CPW T-resonators are designed and measured, with calibrated data agreeing well with other methods up to 30 GHz. Uncalibrated measurements produce dielectric constant and attenuation results within 3.7% and 25%, respectively, of those obtained with calibration. Hence, the CPW T-resonator can be used to provide rapid and accurate characterization of microwave substrates with unknown dielectric properties.

Wide band cross point switch using MEMS technology

Abstract: A multilayer switching assembly for switching high frequency signals has MEMS structures on a ceramic substrate having a top surface, a bottom surface and a plurality of insulating layers. The insulating layers are separated by a first conductor and a second conductor. The first conductor is connected to a ground potential. The second conductor is separated from the first conductor by one of the insulating layers. The second conductor presents a specific impedance (50 ohms) with respect to the first conductor to high frequency signals traveling on the second conductor. 64 MEMS structures are mounted on the top surface. Each MEMS has an input, an output, and a control. The input connected to the second conductor. The output is connected to a coplanar waveguide placed on the top surface. The control is connected to the bottom surface. The input to each MEMS is electrically shielded from the output and from the control by a third conductor connected to the first (grounded) conductor. The third conductor traverses one or more of the insulating layers thereby acting as a shield and precluding the high frequency signals presented to the input from propagating to the output and to the control. The 64 MEMS are arranged in a square 8 by 8 matrix, as well as their controls. High frequency inputs and outputs to be switched by the MEMS are placed on the periphery of the substrate to further enhance the separation of signals. Terminating resistors (50 ohms) are also placed near the periphery.

A New Type of Low Pass Filter With Defected Ground Structure

Abstract: A new design method of low pass filters (LPF) using defected ground structure (DGS) on planar transmission lines such as microstrip and coplanar waveguide (CPW) is presented. LPF is designed easily by extracting the equivalent circuit elements of unit DGS and compensating the line width of capacitive transmission line. The proposed LPF does not have any open stub, discontinuity elements such as Tee-or Cross-junction, and the repeated low-high impedance elements, which have been essential for design of conventional LPF. Only two DGS patterns and one transmission line with broadened width are used for design of the proposed LPF. Simple structure, small size (49% of a conventional LPF), less discontinuities, non-existing of the high impedance lines, no need for wire bonding required in CPW discontinuities, and high power handling capability are obtained through the proposed LPF.

Neural Models for the Resonant Frequency of Electrically Thin and Thick Circular Microstrip Antennas and the Characteristic Parameters of Asymmetric Coplanar Waveguides Backed with a Conductor

Abstract: Summary Neural models for computing the resonant frequency of electrically thin and thick circular microstrip antennas, based on the multilayered perceptrons and the radial basis function networks, are presented. Five learning algorithms, delta-bar-delta, extended delta-bar-delta, quick-propagation, directed random search and genetic algorithms, are used to train the multilayered perceptrons. The radial basis function network is trained according to its learning strategy. The resonant frequency results of neural models are in very good agreement with the experimental results available in the literature. In this paper, the characteristic impedance and the effective permittivity of the asymmetric coplanar waveguide backed with a conductor are also computed by using only one neural model trained by the backpropagation with momentum and the extended delta-bar-delta algorithms. When the performances of neural models are compared with each other, the best results for test are obtained from the multilayered perceptrons trained by the extended delta-bar-delta algorithm.

New periodic-loaded electromagnetic bandgap coplanar waveguide with complete spurious passband suppression

Abstract: In this work, coplanar waveguides (CPW) periodically loaded with shunt capacitances and periodically perturbed by varying the distance between the central strip (of constant width) and ground planes are studied. It is demonstrated that the multiple spurious passbands above the Bragg frequency, inherent to the presence of the reactive elements, can be completely and efficiently rejected by means of very simple geometry perturbation. This result is in contrast to previous works, where the rejection of multiple frequencies requires complex layout patterns and reveals that the elimination of spurious frequency bands in periodic loaded CPWs cannot be merely estimated from the Fourier transform of the perturbation geometry.

Driver-less 40 Gb/s LiNbO/sub 3/ modulator with sub-1 V drive voltage

Abstract: We have succeeded in reducing the drive voltage of a 40Gb/s LiNbO/sub 3/ modulator to 0.9 V, which is the lowest-drive-voltage 40Gb/s LiNbO/sub 3/ modulator in the world. The modulator can be driven within the break down voltage of a SiGe transistor. This result was achieved using a new design concept that featured a wide-gap, long CPW (coplanar waveguide) electrode.

Influence of LaAlO3 surface topography on rf current distribution in superconducting microwave devices

Abstract: A laser scanning microscope with a thermal spot size of about 4 μm is used to measure a quantity proportional to the rf current density in an operating superconducting coplanar waveguide microwave resonator. The twinning of the LaAlO3 substrate produces a meandering of the current at the edges due to irregularities in the wet etching of the YBa2Cu3O7−δ film associated with substrate twin domain blocks, and an (∼20%) enhancement of the rf photoresponse at these locations. These irregularities are candidates for enhanced nonlinear response from the device.

Dispersion analysis of multilayer cylindrical transmission lines containing magnetized ferrite substrates

Abstract: Recently, there has been a growing interest in using cylindrical transmission lines that contain magnetized ferrite material in a variety of applications. In this paper, the finite-difference time-domain (FDTD) method (in cylindrical coordinates) and the spectral-domain analysis (SDA) are used to calculate the propagation characteristics of cylindrical transmission lines that contain magnetized ferrite material. The magnetization can be either in the longitudinal or azimuthal directions. Specifically, the cylindrical microstrip line, and the cylindrical coplanar waveguide printed on magnetized ferrite substrate are analyzed. Both the FDTD and SDA results are in very good agreement. In addition, the results are compared to those of planar structures by taking the radius of the substrate to be large enough such that the curvature effect is negligible.