Showing papers on "Coplanar waveguide published in 1994"

Phased array antenna system including a coplanar waveguide feed arrangement

Abstract: The disclosure relates to a phased array antenna for microwave and millimeter wave applications, using either microstrip line, coplanar waveguide, or other construction techniques incorporating a solid dielectric transmission line. A continuously variable phase delay structure which is used to control the beam pattern of the phased array antenna can be applied to the construction of resonant frequency tunable coplanar waveguide antennas and impedance tunable quarter-wave transformers. A thin film of barium strontium titanate (Bax Sr1-x TiO3) or other nonlinear material such as PbZrx Ti1-x O3 (PZT), LiNbO3, etc. is deposited upon the coplanar waveguide, and/or the patch antenna element. The dielectric constant of the thin film can be made to vary significantly by applying a DC voltage to the thin film. The propagation constant of a transmission line is directly proportional to the square root of the effective dielectric constant (assuming a lossless dielectric). In an array of multiple antenna elements provided with the feed structure using the disclosed transmission lines, the direction of the resultant main beam of the array can be made to vary over a complete half-sphere with only two adjustable DC voltages applied to the dielectric thin films.

CPW-fed active slot antennas

Abstract: We have combined microwave oscillator design with theoretical characterization of planar antennas to build active slot-oscillators. The design is uniplanar, does not require via holes and is compatible with monolithic transistor technology. The coplanar waveguide (CPW) fed antenna impedance is calculated using the space domain integral equation technique (SDIE), a full wave method of moments approach. Slot-oscillators were built at 7 GHz and 20 GHz and the predicted oscillation frequencies agree well with experiments. The 20 GHz medium power oscillator has an output power of 17 mW and a DC to RF efficiency of 14%. The design is easily scaled to millimeter-wave frequencies and can be extended to power combining arrays. >

Integrated laser and coupled waveguide

Abstract: A grating (461) coupling the output of a semiconductor laser (410) in a semiconductor waveguide to a dielectric waveguide (451) having a core (458) which may be efficiently butt-coupled to the core of an optical fiber (470); the laser and semiconductor waveguide, coupling grating, and dielectric waveguide are integrated on a single substrate. Further, multiple lasers (410, 420, 430, 440) with differing lasing frequencies may be integrated and their outputs grating coupled into a single dielectric waveguide (450) for wavelength division multiplexing.

New uniplanar coplanar waveguide hybrid-ring couplers and magic-T's

Abstract: The uniplanar coplanar waveguide (CPW) and slotline on a dielectric substrate have many applications to MIC and MMIC designs. A new reverse-phase CPW hybrid-ring coupler and a uniplanar CPW magic-T were developed. Experimental results showed that the hybrid-ring coupler has a 60% bandwidth centered at 3 GHz and the magic-T has a bandwidth of one octave from 2 to 4 GHz with 0.4 dB amplitude imbalance and 3.5/spl deg/ phase imbalance. Also, this paper presents theoretical analyses of CPW-slotline transitions using the transmission line models. Accurate modeling of nonuniform CPW and slotline radial stubs was developed using tandem connected uniform lines. Measured results of various CPW-slotline transitions agree very well with calculation. Design curves of the transitions are given for practical applications. To fully use the advantages of uniplanar structures, a 180/spl deg/ reverse-phase CPW-slotline back-to-back balun and a tee junction are described. Both circuits provide good amplitude and phase characteristic over a broad bandwidth due to the phase change of the circuits being independent of frequency. >

Characterization of high frequency interconnects using finite difference time domain and finite element methods

Abstract: MIC and MMIC packages capable of good performance at frequencies as high as 60 GHz need to have small volume, low weight, microstrip and/or coplanar waveguide (CPW) compatibility and exhibit negligible electrical interference with the rest of the circuit. In order to acquire some of these characteristics, special provisions need to be made during circuit layout and design, resulting in high-density packages. The designed circuits have a large number of interconnects which are printed on electrically small surface areas and communicate through the substrate in a direct through-via fashion or electromagnetically through appropriately etched apertures. In a circuit environment of this complexity, parasitic effects such as radiation and cross talk are intensified, thus, making the vertical interconnection problem very critical. In this paper, transitions using through-substrate vias are considered and analyzed both in the time and frequency domains using the Finite Difference Time Domain (FDTD) technique and the Finite Element Method (FEM), respectively. The merits of each method in conjunction with accuracy, computational efficiency and versatility are discussed and results are compared showing excellent agreement. Specifically, a microstrip short-circuit, a microstrip ground pad, a CPW-to-microstrip through-via transition and a channelized CPW-to-microstrip transition are analyzed and their electrical performance is studied. >

Coplanar waveguide fed coplanar strip dipole antenna

Abstract: A novel coplanar waveguide fed coplanar strip dipole antenna is presented. Return loss data as well as antenna patterns are shown. The antenna is matched with the use of a novel, wideband balun.

Terahertz-bandwidth characteristics of coplanar transmission lines on low permittivity substrates

Abstract: Coplanar striplines and waveguides capable of supporting ultra-high-frequency pulses over many millimeters of propagation length have been fabricated on low-permittivity substrates, including a durable 1.4-/spl mu/m-thick membrane. These transmission lines were characterized using broadband pulses from a novel in situ optoelectronic test-signal generator together with an electro-optic probe tip and an optically-based sampling technique. Pulse-propagation characteristics for the coplanar lines on the low-permittivity substrates have been compared in both the time and frequency domains with the transmission behavior of lines on GaAs substrates. A semi-empirical model has also been used to simulate the experimental results with good agreement, helping to indicate the origin of the distortion mechanisms involved. In addition, for the coplanar waveguide structures, waveforms corresponding to the even and odd modes have been individually resolved in the time domain for lines fabricated on the GaAs and membrane substrates. >

Kinetic Inductance of Superconducting Coplanar Waveguides

Abstract: An analytical expression for the kinetic inductance of the superconducting coplanar waveguide is given using the conformal mapping technique. This expression is shown to be in good agreement with experimental results obtained from the temperature dependence of the resonant frequency of the NbN coplanar waveguide resonators, especially in the case of a film thickness smaller than the magnetic penetration depth. It is also shown that the magnetic penetration depth of the superconducting thin films can be evaluated by this method.

Experimental analysis of millimeter wave coplanar waveguide slow wave structures on GaAs

Abstract: Microwave coplanar waveguide slow wave structures suitable for use in traveling wave electrooptic modulators were experimentally investigated to 40 GHz. Velocity slowing is achieved by introducing periodic slots in the ground planes. Structures both on semiinsulating GaAs substrates and on epitaxial layers grown by molecular beam epitaxy on semiinsulating GaAs substrates were examined. In the measurements the thru-reflect-line calibration method was used and its limitations are discussed. The characteristic impedance, phase velocity and loss coefficient of these lines were extracted from measured S-parameters. Effects of various dimensions on these line properties are presented and discussed. Results indicate that significant phase velocity slowing without dispersion at least up to 40 GHz is possible with this approach. This is true both on semi-insulating GaAs substrates and specially designed epitaxial layers. A design approach to achieve a specified phase velocity and characteristic impedance is given. >

Electrically controlled HTSC/ferroelectric coplanar waveguide

Abstract: It is shown that in an integrated YBa/sub 2/Cu/sub 3/O/sub 7/SrTiO/sub 3/ structure coplanar waveguide (CPW) electrical control of microwave propagation characteristics is possible. Microwave losses of less than 0.2 dB/cm at 10 GHz can be achieved at liquid nitrogen temperatures, provided ferroelectric films with perfect crystalline structures are used. Electrically controlled changes in effective dielectric permittivity of more than 40% are predicted at 77 K and 10 GHz. Sections of these CPWs can be used in electrically controlled phase shifters and resonators.

Analytical analyses of v, elliptic, and circular-shaped microshield transmission lines

Abstract: Several new types of monolithic coplanar transmission lines, v, elliptic, and circular-shaped microshield coplanar waveguide, have been proposed. The characteristic impedance expressions for those transmission lines have been derived using the conformal mapping method (CMM) under the assumption of the pure-TEM propagation and zero dispersion. In the analyses of the elliptic and the circular-shaped microshield coplanar lines, the methods using the graphical approximation and taking the geometric mean value of the upper and the lower bounds to the size of the line are put forward to calculate the characteristic impedance of this two kinds of microshield coplanar lines. The numerical results show the effects of the different shaped microshield walls on characteristic impedances. >

Characterization of coplanar waveguide open end capacitance-theory and experiment

Abstract: The theory, numerical analysis, analytical approximate formula, measurement technique, and characteristic curves were presented in this paper for the characterization of coplanar waveguide open end capacitance. A novel variational equation was proposed in terms of the scalar potential on the slot aperture and was solved by applying the finite element method. With the available analytical Green's function and exact integration formulas in the space domain, this approach was found to be quite efficient and suitable for analyzing the coplanar waveguide discontinuity problems-even with more complicated geometrical configurations. Numerical results were compared to those obtained numerically and experimentally in previous literature, but did not correlate very well. An analytical formula under narrow-slot assumption was thus derived to render a verification of numerical results. Measurement by utilizing the resonance method were also made and the experimental data confirmed the validity of our theory. The relationship between the capacitance and the physical dimensions was also investigated. The characteristic curves of the open end capacitance were obtained. Also, an empirical formula was established for the open end structures with a thick substrate and narrow gap. >

Generation of subpicosecond electrical pulses by nonuniform illumination of GaAs transmission-line gaps

Abstract: We present a detailed study of subpicosecond pulse generation by nonuniform illumination of transmission-line gaps on semiinsulating GaAs. The dependence of such pulses on bias voltage, light intensity, and wavelength was examined in detail with the aid of a subpicosecond electrooptic sampling system. A complete spatial mapping of the excitation area indicates that the pulse generation is due to the depletion of the electrical field in the illuminated section of the gap. A comparison of uniform and nonuniform gap excitation schemes pinpointed the physical differences between the two processes of electrical-transient generation. Picosecond pulses were also generated by nonuniform illumination of a photoconductive gap placed in series with a coplanar waveguide for the first time and were found to contain balanced, odd modes only. >

Quasi-static conductor loss calculations in transmission lines using a new conformal mapping technique

Abstract: A new approximation technique to find the total series impedance per unit length for quasi-TEM transmission lines including conductor loss has been developed. It is shown through the use of conformal mapping that both frequency dependent skin-depth and proximity effects can be accurately modeled. Comparison between experimental measurements and calculations for twin-lead, coplanar strips, parallel square bars, and coplanar waveguide all show excellent agreement. This technique is easily generalized to any transmission line making use of polygonal cross-section conductors. >

High yield GaAs flip-chip MMICs lead to low cost T/R modules

Abstract: A flip-chip design and assembly technique has been developed for GaAs MMICs resulting in lower fabrication costs and improved module yields. Plated bumps on the face of the MMIC are used as a replacement for wirebonds to interconnect all DC and RF signals. Wafer thinning, backside via etch, and backside plating steps have been eliminated, resulting in both higher fabrication yields and improved assembly yields. Microstrip matching networks have been replaced with uniplanar transmission structures such as Coplanar Waveguide (CPW) and spiral inductors. RF data will be shown to validate the design and assembly methods. Results will be shown indicating that flipped high-power MMICs provide lower thermal resistances than their unflipped counterparts, resulting in lower junction temperatures and improved reliability. >

Waveguide and plane line converter

Abstract: PURPOSE: To avoid impedance mismatching and improve high frequency characteristics by employing three-layered structure including a dielectric substrate for a plane circuit board and coplanar structure for a strip line connected to an antenna pattern. CONSTITUTION: The plane circuit board 2 is formed of three layers of grounding single bodies 5, 8, and 9 between which 1st and 2nd alumina ceramic thin plates 3 and 4 of dielectric substrates are sandwiched. Then a thin plate 3 in the frame of a conductor 5 sealing the opening of an internal waveguide 1 is provided with the antenna pattern 6 which has a via hole 10, the antenna pattern is connected to a strip conductor 7 provided to the thin plate 4 through the hole 10, and the conductor 7 forms a coplanar line together with a conductor 8 at its periphery. In this constitution, the conductor 7 is regarded as a ground conductor to avoid impedance mismatching due to the inductance generated in the via hole 11, thereby obtaining the waveguide and plane line converter which is increased in high frequency characteristics. COPYRIGHT: (C)1996,JPO

Microwave electro-optic mixer

Abstract: An electro-optic mixer includes means for providing first and second microwave signals having first and second frequencies, respectively, a device for providing a source light, a first modulator responsive to the source light and to the first microwave signal for producing a first modulated optical signal, a second modulator cascade coupled to the first modulator and being responsive to the first modulated signal and to the second microwave signal for producing a second modulated optical signal having a frequency component at the sum or difference or both of the first and second frequencies, and means coupled between the first and second modulators for transmitting the first modulated signal to the second modulator Each of the first and second modulators is a broadband, low drive voltage, traveling wave intensity modulator including a substrate having a first optical waveguide adapted to receive and transmit light therethrough with a first phase velocity; a buffer layer disposed on the substrate; and a coplanar waveguide electrode structure on the buffer layer for receiving an electrical signal propagating therethrough with a second phase velocity to phase modulate the light in the optical waveguide The substrate has a sufficiently small thickness so that coplanar mode-substrate mode coupling substantially does not occur, and the coplanar waveguide electrode structure has a sufficiently large thickness so that the first and second phase velocities are equal

Compensation for Substrate Permittivity in Probe-Tip Calibration

Abstract: We demonstrate a method of compensation for the effect of substrate permittivity on coplanar waveguide probe-tip scattering parameter calibrations, modeling the effect as a capacitance at the probe tip. Comparison to on-wafer multiline TRL calibration verifies its accuracy. The method allows calibration to the probe tip using generic off-wafer standards with accuracy comparable to that of on-wafer calibration.

Optical non-reciprocal circuit of waveguide type

Abstract: An optical non-reciprocal circuit is constituted by a channel waveguide, a planar waveguide, and a diffraction lattice or grating. The channel waveguide is disposed in a planar substrate that is transmissive to optical waves. The planar waveguide is disposed on only one side of a substrate plane divided by the channel waveguide in the substrate plane and having an equivalent refractive index lower than that in the channel waveguide. The diffraction grating provides a spatial periodic change of the refractive index to a guided optical wave of the channel waveguide. The periodicity of the lattice direction, that is, the direction of the wavenumber vector is neither parallel nor perpendicular to the optical transmission direction of the channel waveguide but is given a finite angle. The optical non-reciprocal circuit can be realized by using only an ordinary dielectric material with the circuit being highly productive and low priced and having high performance.

High gain monolithic W-band low noise amplifiers based on pseudomorphic high electron mobility transistors

Abstract: Five versions of monolithic W-band 0.1 μm AlGaAs/InGaAs/GaAs pseudomorphic High Electron Mobility Transistor, four-stage, Low Noise Amplifiers based on two different designs were developed. These millimeter wave monolithic integrated circuits have produced a minimum noise figure of 3.5 dB with 23.0 dB gain at 92 GHz and a maximum gain of 33.5 dB with a 6.2 dB noise figure at 102 GHz. This is the highest gain yet reported for a single chip W-band amplifier. The chips feature coplanar waveguide circuit elements and compact size for low-cost production, single-polarity bias requirement, and a minimum of DC bonding pads

Calculation of CPW AC resistance and inductance using a quasi-static mode-matching approach

Abstract: The AC resistance and inductance of a coplanar waveguide with nonideal conductivity are computed by means of a quasi-static mode-matching method. Convergence is examined and the numerical results are compared to those obtained by a full-wave mode-matching method. Regarding the frequency dependence, significant influence of the conductor losses is found. >

High gain monolithic W-band low noise amplifiers based on pseudomorphic high electron mobility transistors

Abstract: Five versions of monolithic W-band 0.1 /spl mu/m AlGaAs-InGaAs-GaAs pseudomorphic HEMT, four-stage, low noise amplifiers based on two different designs were developed. These millimeter wave monolithic integrated circuits have produced a minimum noise figure of 3.5 dB with 23.0 dB gain at 92 GHz and a maximum gain of 33.5 dB with a 6.2 dB noise figure at 102 GHz. This is the highest gain yet reported for a single chip W-band amplifier. The chips feature coplanar waveguide circuit elements and compact size for low-cost production, single-polarity bias requirement, and a minimum of DC bonding pads. >

Packaging of printed-circuit lines: a dangerous cause for narrow pulse distortion

Abstract: We report here a new behavioral feature of a narrow pulse transmitted on coplanar waveguide (CPW), putting the special stress on the effects caused by the packaging of such a waveguide. This feature occurs due to the unexpected simultaneous combination of a distortion in the guided main pulse and a production of delayed echo pulses. An explanation based on a new class of the dominant-mode power-leakage effect leads to a clear physical understanding of why such features necessarily appear. >

Control of leakage in multilayered conductor-backed coplanar structures

Abstract: The spectral domain technique with a complex root searching procedure is used to investigate leakage phenomena in the multilayered conductor-backed coplanar waveguides. It is found that the leakage in the conventional conductor-backed CPW can be controlled by introducing an additional dielectric layer over certain frequency range with appropriately chosen geometry. However, these multilayered structures will leak when frequency is sufficiently high. Two different multilayered structures are given as examples. >

Membrane technology (MIST-T) applied to microstrip: a 33 GHz Wilkinson power divider

Abstract: Application of membrane technology to transmission line design leads to broad-band, pure TEM wave propagation and thus excellent electrical characteristics. This approach has previously been demonstrated using a coplanar waveguide geometry, and is now used to develop a membrane-based microstrip line. The new geometry exhibits nearly ideal wave guiding properties, and is utilized here in a low-loss 33 GHz Wilkinson power divider. >

Numerically efficient spectral domain approach to the quasi-TEM analysis of supported coplanar waveguide structures

Abstract: A numerically improved technique for the quasi-TEM analysis of supported coplanar waveguides is presented. The spectral domain method is combined with a special set of basis functions, to facilitate an accurate and efficient solution. The resulting integrals are evaluated using closed-form expressions instead of numerical integration scheme which leads to short CPU time. In this study, numerical results for the characteristic impedances of coplanar waveguides are presented. Comparisons are also made between the computed results and available ones. The charge density distributions on the center signal strip as well as on the ground plane are examined. >

A balanced Ka-Band GaAs FET MMIC frequency doubler

Abstract: A simplified and miniaturized state-of-the-art balanced GaAs FET MMIC frequency doubler operating at 36 GHz has been designed and realized in coplanar waveguide technology. The passive part of the circuit is designed using an effective, in-house developed quasi-static finite-difference method for the analysis of coplanar structures while the active device is characterized by using the Curtice-Ettenberg model. The model makes use of the measured electrical values of the transistor and interprets them through approximate empirical formulas. The results obtained demonstrate that by using simple models, which require very little computation time, it is possible to design an efficient frequency doubler in the Ka-band with a maximum conversion gain of 3 to 6 dB, without the need of using complicated transistor models or circuitry. >

Contactless electrical characterization of MMICs by device internal electrical sampling scanning-force-microscopy

Abstract: For the first time a scanning force microscope based test system is used for device internal electrical characterization of monolithic microwave integrated circuits (MMIC) based on III-V-semiconductor material up to 40 GHz. Measurements on a coplanar waveguide and within a travelling wave amplifier (TWA) demonstrate the capability for a device internal function- and failure analysis of MMICs. The experimental results are completed by network analyzer measurements. >

2 GHz Bandwidth Predistortion Linearizer for Microwave Power Amplifiers at Ku-Band

Abstract: Modern communication satellites carrying large numbers of signals require High PoWer Amplifiers (HPAs) which provide RF power with high linearity and high efficiency. Solid state power-amplifiers (SSPAs) and travelling-wave tube amplifiers (TWTAs) are the candidates for thiS application. Predistortidn linearizer circuits, are used to improve the performance of these aimplifier types. A 10.7 to 12.75 GHz predistortion linearizer is realized in coplanar waveguide tchnology with only three active elements, two Schottky diodes and one monolilthic microwave integrated circuit (MMIC) amplifier. This linearizer shows good capabilities for gain and phase adjustments: gain expansion of 5 dB and phase shift between 20 and 50 degrees can be obtained with this circuit over 2 GHz of bandwidth and about 10 - 12 dB input power dynamic range. Furtheron, the linearizer offers an input and output VSWR of better 1.4 : 1 over bandwidth. Low mass and size and increased reliability makes this linearizer suitable for satellite as well as for ground station applications.

A 50 GHz broad-band monolithic GaAs/AlAs resonant tunneling diode trigger circuit

Abstract: This paper describes the design, circuit simulation, fabrication and testing of a 50 GHz trigger circuit using GaAs/AlAs resonant tunneling diodes. A new trigger circuit was designed to eliminate the 180/spl deg/ phase splitter used in a previous complementary input trigger circuit. Our monolithic approach, integrated GaAs/AlAs resonant tunneling diodes (in a back-to-back configuration) and a 50 /spl Omega/ coplanar waveguide, minimized the parasitic circuit elements and internal reflections from the package thus achieving high frequency operation. The circuit was able to trigger on input sinusoidal waves of input powers of -3 dBm up to 50 GHz with time jitter of less than 1 ps rms over the entire measured frequency range from 5 to 50 GHz. The upper limit of 50 GHz was imposed by our measurement system. >