Showing papers on "Coplanar waveguide published in 1990"

Propagation modes and dispersion characteristics of coplanar waveguides

Abstract: The coplanar waveguide (CPW) structure is subdivided into five classes based on substrate thickness, backside metallization, and ground plane width. Radiation and guided modes are studied in each class, and their effects on loss and dispersion are described. For coplanar waveguides, dispersion due to interaction with surface wave parallel-plate modes in the substrate strongly depends on the ground-to-ground spacing (W+2G). If this spacing is small compared to dielectric wavelength and substrate thickness, both dispersion and radiation losses are minimized. In finite ground plane cases, small ground-to-ground spacing compared to substrate thickness is necessary to avoid the excitation of the microstrip mode and to minimize the deviation of the CPW mode from the odd mode of the ideal line. Limitations on the reduction of (W+2G) come from conductor loss, which imposes a minimum width requirement on the center conductor. If substrate thickness is to be kept large compared with this dimension, it is inevitable that, at high frequencies, the operation of the CPW will not be below the cutoff frequency of surface wave modes. However, the interaction of the CPW mode with surface wave modes is negligible for integrated circuit applications when ground-to-ground spacing is small compared with dielectric wavelength. >

Full-wave analysis of conductor losses on MMIC transmission lines

Abstract: A mode-matching analysis of lossy planar transmission lines is presented. This method uses a modified mode-matching technique developed for travelling-wave FET analysis. The metallic layers are treated in the same way as the remaining waveguide subregions, with each of them characterized by its complex dielectric constant. This leads to a fully self-consistent description of the conductor losses. In contrast to the usual perturbation methods, it includes metallic loss by a self-consistent description without any skin-effect approximation. The analysis holds for arbitrarily high losses and also for metallization dimensions smaller than the skin depth. The approach is validated by comparison with previous experimental and theoretical work. Monolithic microwave integrated circuit (MMIC) microstrip and coplanar lines are investigated. The variation in propagation characteristics for typical metallization thickness is studied and the consequences with regard to MMIC design are discussed. For the coplanar waveguides (CPWs) significant deviations compared to the conventional assumption of lossless zero-thickness strips are found. >

Three-dimensional microwave circuit carrier and integral waveguide coupler

Abstract: A non-hermetic, three-dimensional, microwave semiconductor device carrier with integral waveguide couplers is disclosed A molded plastic substrate having a suitable dielectric constant and varying thicknesses comprises plated conductors and locations for receiving GaAs MMIC's MMIC's are mounted to a metal backplate and die bonded to the plated conductors The waveguide couplers are integrally molded as part of the carrier substrate, and comprise plated through cylindrical members Signals from a waveguide cavity are coupled to the MMIC's by inserting the waveguide couplers into a waveguide port The carrier and integral waveguide coupler together with a plated molded cover forms a non-hermetic package providing pseudo-shielding cavities about the resident multiple semiconductor GaAs die Transmission line impedance control is enhanced varying the substrate thickness on a per conductor basis Frequency of operation exceeds 12 gigahertz

Method of manufacturing an interconnect device having coplanar contact bumps

Abstract: An interconnect or circuit device having coplanar contact bumps, and the method of manufacture thereof are presented. The coplanar contact bumps are formed against a flat reference surface whereby the resulting bumps have coplanar means.

Equivalent capacitances of coplanar waveguide discontinuities and interdigitated capacitors using a three-dimensional finite difference method

Abstract: Equivalent capacitances of coplanar waveguide discontinuities on multilayered substrates are calculated using a three-dimensional finite-different method. The application of the method is demonstrated for open ends and gaps in microstrip and coplanar waveguides, as well as for more complicated structures such as interdigitated capacitors. The main advantage of the method is its flexibility in treating multilayered substrates and different conductor configurations. It can therefore be applied to more complicated structures such as interdigitated capacitors, air bridges, and waveguide transitions. The effect of conductor metallization thickness and shielding walls is also taken into account. Good agreement between the calculated data and measurements up to 25 GHz in the case of coplanar structures indicates the validity of the static analysis even for high frequencies. >

Characterization of MIS structure coplanar transmission lines for investigation of signal propagation in integrated circuits

Abstract: A full-wave analysis of metal-insulator-semiconductor (MIS) structure micron coplanar transmission lines on doped semiconductor substrates is carried out using a finite-difference time-domain approach. Metal conductor loss is taken into account in the analysis. Line parameters and electromagnetic field distributions are calculated over a wide frequency range involving slow-wave and dielectric quasi-transverse-electromagnetic mode limits. Measurements of these line parameters, varying substrate resistivity from 1 to 1000 Omega -cm, in the frequency range up to 40 GHz are also presented, and these agree with the analysis quite well. On the basis of these results, an equivalent circuit line model is induced and some considerations on the relationship between line structure and properties made. >

5-100 GHz InP coplanar waveguide MMIC distributed amplifier

Abstract: A single-stage 5-100-GHz InP MMIC (monolithic microwave integrated circuit) amplifier with an average gain of more than 5.5 dB has been developed. This MMIC distributed amplifier has the highest frequency and bandwidth of operation (5-100 GHz) reported to date for wideband amplifiers. The average associated (not optimized) noise figure of the MMIC amplifier was approximately 5.8 dB measured over 4-40 GHz. The active devices in this seven-section distributed amplifier were 0.1- mu m mushroom gate, InGaAs-InAlAs lattice-matched HEMTs (high electron mobility transistors) on a semi-insulating InP substrate. A coplanar waveguide was the transmission medium for this 100-GHz MMIC with an overall chip dimension of 500 mu m by 860 mu m. >

Planar active endfire radiating elements and coplanar waveguide filters with wide electronic tuning bandwidth

Abstract: Microwave and millmeter-wave system components are fabricated by using slotlines extending from the periphery of CPW resonators This technique permits the degree of electrical coupling between the CPW and and the slotlines to be adjusted for matching, and the CPW resonators and slotlines behave as if they were relatively independent circuit elements, permitting transmission line models to be useful design tools and predicting the behavior of the system components The system components are fully planar and allow easy integration of active and passive semiconductor devices in series with the CPW, and in shunt across the slotlines in hybrid and monolithic circuit forms This technique also enables the conductive plane to be split for biasing semiconductor devices coupled to the CPW resonators for microwave and millimeter-wave power generation, tuning, mixing, filtering, frequency multiplication and switching Integration with a notch antenna and slot-to-microstrip transitions are also described which permit a direct radiation/reception or a coaxial connector output

A new rectangular waveguide to coplanar waveguide transition

Abstract: A novel rectangular-waveguide-to-coplanar-waveguide transition is described. The transition uses a ridge in one of the broad walls of the waveguide and a nonradiating slot in the opposite wall to split and rotate the electromagnetic fields of the rectangular waveguide TE/sub 10/ mode into the coplanar waveguide (CPW) fields. This transition should permit the use of CPW-based circuits in the millimeter-wave frequency range and the development of microwave probes above 50 GHz for fast and inexpensive testing of the millimeter-wave circuits. >

Fullwave analysis of picosecond photoconductive switches

Abstract: A fullwave analysis method for characterizing fast photoconductive switches (PCs) is proposed. Three-dimensional Maxwell curl equations, including the conductive current components, are solved using a finite-difference time-domain scheme. It is found from simulations that PCs in coupled microstrip lines with small widths and spacings are very effective in avoiding propagation of non-quasi-TEM modes and for achieving rapid responses. Futhermore, responses for PCs with pulse-forming networks constructed of coplanar waveguide shunt electrodes are simulated. Ultrashort electrical pulses with minimum widths of 0.2 and 0.4 ps can be obtained by symmetric and antisymmetric excitation methods, respectively, for linewidth and spacing readily realized. >

5-100 GHz InP CPW MMIC 7-section distributed amplifier

Abstract: The development of a single-stage 5-100-GHz InP monolithic microwave IC (MMIC) amplifier with an average gain of more than 5.0 dB is reported. This MMIC distributed amplifier has the highest frequency and bandwidth of operation (5-100 GHz) reported for wideband amplifiers. The active devices in this seven-section distributed amplifier are 0.1- mu m mushroom-gate InGaAs-InAlAs lattice-matched HEMTs on a semiinsulating InP substrate. Coplanar waveguide is the transmission medium for this 100-GHz MMIC with an overall chip dimension of 500 by 860 mu m. This is the first 100-GHz coplanar waveguide circuit on an InP substrate. >

Space-saving two-sided microwave circuitry for hybrid circuits

Abstract: A space-saving, two-sided microwave transmission line for hybrid circuits is disclosed, wherein a microstrip or coplanar waveguide RF line is formed on the front side and a microstrip or coplanar waveguid RF transmission line is formed on the backside of a hybrid circuit board containing other components. The RF line is formed on the top side of the circuit board to facilitate connections to other circuit boards and/or RF components, but is routed underneath the board to traverse the areas of the board occupied by other components. When the RF line is on the top side of the substrate, the groundplane is established by the metal layer on the bottom of the substrate for a microstrip line and by a top metal layer for a coplanar waveguide line, and when the RF line is on the bottom of the substrate, the groundplane is established with the metal layer on top of the substrate for a microstrip line, and with the bottom metal layer for a coplanar waveguide line. The connection from the topside and backside RF lines is accomplished by low VSWR plated via holes through the substrate.

Optically controlled coplanar waveguide phase shifters

Abstract: The progress and ongoing development of optically controlled phase shifters, primarily those based on the use of coplanar waveguide (CPW) printed on semiconductor substrates, are reviewed. Slow-wave phenomena in such guides, their possible use to produce variable phase shifts, and several different approaches using these phenomena to implement phase shifts are qualitatively described. Two main techniques, one based on the use of Schottky-contact CPW electrodes and the other on optically generated carriers, are discussed, as is the experimental performance of prototype devices using these control mechanisms. A technique based on the combined use of Schottky contacts and optical illumination is discussed. Preliminary results on such a device indicate that this technique is a promising alternative to a purely Schottky contact or purely optical control while preserving advantages of both techniques. >

Coplanar waveguide semiconductor package

Abstract: A package for a semiconductor device includes a base having a flat surface with an edge of a predetermined shape for abutting against a similar edge of another object. Conductors are placed on the flat surface of the base and extend to but do not overlap the edge of predetermined shape. The base along with a frame and a cover cooperate to provide a package which encloses and protects the semiconductor device. The package can be placed adjacent a similarly shaped package so that the overall structure takes up a minimal amount of space. Ground planes located on the base can be readily interconnected.

Characterization of surface-undoped In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InP high electron mobility transistors

Abstract: High-performance 0.3- mu m-gate-length surface-undoped In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InP high-electron-mobility transistors (HEMTs) grown by molecular beam epitaxy (MBE) have been characterized and compared with a surface-doped structure. At 18 GHz, the surface-undoped HEMT has achieved a maximum stable gain (MSG) of 19.2 dB compared to 16.0 dB for the surface-doped structure. The higher MSG value of the surface-undoped HEMTs is obtained due to the improved g/sub m//g/sub 0/ ratio associated with the surface-induced electric field spreading effect. Comparison of identical 0.3-*150- mu m-gate devices fabricated on surface-undoped and -doped structures has shown greatly improved gate leakage characteristics and much lower output conductance for the surface-undoped structure. It is demonstrated that the surface potential, modulated by different surface layer designs, affects the charge control in the conducting channel, especially the carrier injection into the buffer, resulting in excess output conductance. Several millimeter-wave coplanar waveguide (CPW) monolithic distributed amplifiers have been successfully fabricated by using the surface-undoped HEMT structure. A high gain per stage distributed amplifier with 170-dB+or-1-dB small-signal gain across a frequency band of 24-40 GHz, a W-band monolithic integrated circuit with 6.4-dB gain at 94 GHz, and a broad bandwidth distributed amplifier with 5-dB gain across a frequency band of 5 to 100 GHz have been demonstrated by using the surface-undoped structures. >

Periodic-structure photoexcitation of a silicon coplanar waveguide for selective optoelectronic microwave control

Abstract: Presented is a detailed analysis of the microwave Bragg-reflection characteristics of a periodically continuous-wave (CW) photoexcited coplanar waveguide on silicon substrate, with special regard to the inherent carrier diffusion mechanisms. In particular, the carrier diffusion in the direction of wave propagation can strongly affect the stopband reflection spectra of the configuration with respect to magnitude and bandwidth or with respect to efficiency and selectivity. The dominant effects are studied quantitatively and are outlined in the form of practical performance diagrams. Future application of periodically photoexcited transmission line sections for light-induced tunable filters or Bragg reflectors can be inferred. Initial experimental results from a three-section periodic structure of 17-GHz-center frequency under 840-nm light emitting diode (LED) CW excitation are reported. >

Planar microwave antenna for producing circular polarization from a patch radiator

Abstract: A planar antenna is described which employs a thin patch of conductive material supported above and substantially parallel to a closely spaced thin conductive ground surface. Two or more narrow slots are positioned in the ground surface beneath the conductive patch. A microstrip transmission line, placed below the ground surface, excites the slots in series. The length of the microstrip line between the slots, the position of the microstrip line across the slots, and the dimensions of the slots are chosen to excite two orthogonal modes in the conductive patch in phase quadrature. This excitation results in a planar antenna which receives and transmits electromagnetic waves of circular polarization. The antenna may also employ a coplanar waveguide transmission line instead of the aformentioned microstrip transmission line. The coupling apertures then form slot discontinuities in series with the coplanar transmission line, which are positioned under the conductive patch. The antenna may also employ several conductive patches stacked over each other in a parallel fashion to enhance antenna performance.

New waveguide-to-coplanar waveguide transition for centimetre and millimetre wave applications

Abstract: A novel waveguide-to-coplanar waveguide adaptor useful for microwave and millimetre wave applications is described. The feasibility of the adaptor has been established through tests performed on X-band and Ka-band prototype structures. Satisfactory operation above 100 GHz is anticipated.< >

100 GHz high-gain InP MMIC cascode amplifier

Abstract: A high-gain InP MMIC (millimeter-wave IC) cascode amplifier is developed which has 8.0 dB of average gain from 75 to 100 GHz when biased for maximum bandwidth, and more than 121 dB of gain at 80 GHz at the maximum-gain bias point, representing the highest gains reported to date, obtained from MMICs at W-band (75-100 GHz). Lattice-matched InGaAs-InAlAs HEMTs with 0.1 mu m gates are the active devices. Coplanar waveguide (CPW) is the transmission medium for this MMIC with overall chip dimensions of 600 mu m by 500 mu m. Device fabrication, modeling circuit design, and measurement results are reported. >

Machined waveguide twist

Abstract: A solution to the problem of obtaining a 90 degrees twist in a machined-aluminium block waveguide is presented At the waveguide input, half the waveguide wide-dimension is machined into one aluminum block the mirror image being machined into a second block The technique involves gradually reducing the width of the input waveguide in one block, and simultaneously increasing the depth of the waveguide in the opposite block until the output waveguide depth is equal to the input waveguide width Care must be taken to maintain a constant waveguide cutoff frequency through the length of the twisted section so that a good match is obtained Two twists made using this technique in WR-22 waveguide are shown to give satisfactory results >

Asymmetric coplanar-strip transmission lines for MMIC and integrated optic applications

Abstract: Microwave transmission lines with coplanar electrodes on dielectric or semiconductor substrates are widely used in integrated optic travelling-wave modulators and optical control microwave attenuators/modulators. The reduction of the drive voltage in travelling-wave modulators and control power in optical control microwave attenuators is achieved by reducing the width of the gap between the coplanar strips. When reducing the gap width in these devices special care must be taken to keep the characteristic impedance, Z0, high. Although symmetric coplanar and coplanar-strip waveguides, have been used, asymmetric coplanar-strip waveguides seem to be highly flexible in practical device design. Along with small sizes, the impedance, Z0, effective dielectric constant, in e, and microwave refractive index, nm, can be adjusted by changing the width of one of the strips while keeping the width of the other strip and of the gap fixed. The basic parameters ( in e,C,Z0) of asymmetric coplanar-strip waveguides on finite thickness substrate are reported.

Microwave frequency range electro-optic modulator with efficient input coupling and smooth wideband frequency response

Abstract: A travelling-wave Mach-Zehnder electro-optic modulator (10) for operation at microwave electrical input signal frequencies has an electrical modulation electrode structure (26,34) which constitutes a coplanar waveguide (24). An electrical input signal connector (80) is coupled to a microstrip line (38) having an output impedance which is significantly different from the input impedance of the waveguide (24). A Chebyshev impedance matching transformer (50) couples the input signal from the input connector (80) to the modulation electrode structure (26,34), while matching the output impedance of the microstrip line (38) to the input impedance of the waveguide (24) to maximize the coupling efficiency and minimize return loss. The modulato GOVERNMENT RIGHTS This invention was made with Government support under Contract No. N66604-87-C-1126 awarded by the Department of the Navy. The Government has certain rights in this invention.

Monolithic GaAs W-band pseudomorphic MODFET amplifiers

Abstract: A unique realization of a single-stage monolithic GaAs W-band amplifier based on InGaAs-AlGaAs pseudomorphic (PM) MODFET devices is reported. This work reflects a number of significant accomplishments: (1) superior control of MBE to grow the PM layers, (2) well-developed electron-beam 0.1 mu m mushroom-gate technology, (3) reliable physical and equivalent-circuit models of device behavior, (4) layouts that minimize parasitics, and (5) a dual-medium circuit approach consisting of coplanar waveguide (CPW) and microstrip on opposite faces of a 100 mu m-thick GaAs substrate. A peak gain of 4.5 dB at 92 GHz for one of the amplifiers was achieved. The measured gain is in good agreement with the model predictions. >

A three-dimensional finite-difference calculation of equivalent capacitances of coplanar waveguide discontinuities

Abstract: A finite-difference method is applied to three-dimensional multilayered shielded structures containing planar waveguide discontinuities. The electric field distribution inside the shielded structure is computed, and the equivalent capacitances of the discontinuities are determined. Open-ends and gaps in various coplanar waveguides with one- and two-layer substrates as well as more complicated structures like interdigitated capacitors are examined. The calculated results are in good agreement with accurate measurements and results from other methods. >

Full-wave analysis of coplanar waveguides by variational conformal mapping technique

Abstract: A new full-wave analysis of coplanar waveguides is presented. The modified mapping technique of C.P. Wen (1969) is used to map the original infinite domain into a finite image domain and also to account for the singularity of fields near the conductor edges. The finite thickness of the dielectric substrate is considered together with the assumptions of lossless guides and negligible metallization thickness. The current distributions on the center signal strip as well as the tangential electric fields over the slot along the air-dielectric interface are examined. Numerical results for the frequency-dependent effective dielectric constants and characteristic impedances of coplanar waveguides are presented. Particular attention is given to the electric field distributions over the air-dielectric interface of slots and the current distributions of the signal strip. >

Microwave plasma source apparatus

Abstract: A microwave plasma source apparatus having a combination of a plane waveguide with a cylindrical coaxial waveguide. Microwave power is efficiently supplied to a body of discharge plasma produced inside a discharge tube located along the central axis of an inner conductor of the cylindrical coaxial waveguide. The plane waveguide has an open end through which to introduce microwave power and an end plate installed opposite to the open end. The cylindrical coaxial waveguide has its central axis located one quarter of the wavelength of the microwave power in use away from the end plate of the plane waveguide toward its open end. The inner and outer conductors of the cylindrical coaxial waveguide are coupled respectively with the bottom and upper walls of the plane waveguide. This arrangement allows the cylindrical coaxial waveguide to function as an efficient mode transformer addressing the microwave electromagnetic field formed in the plane waveguide. This in turn makes it possible to produce microwave plasma of large power at high degrees of efficiency.

Resistive planar ring double-balanced mixer

Abstract: A passive uniplanar double-balanced RF mixing apparatus, comprising a planar support substrate with first and second conductive layers disposed on first and second sides, and first and second linear slotlines having open terminations on a first end thereof formed in the first conductive layer. First and second coplanar waveguides are also formed in the first conductive layer with each having one end electrically coupled to first and of said first and second slotlines, respectively. A first balun comprises the first coplanar waveguide connection to the first slotline, and a second balun comprises the second coplanar waveguide connection the second slotline. An isolation gap formed in the first conductive layer adjacent to and between the first and second slotlines provided electrical isolation between the first and second baluns and waveguides for RF-toLO isolation. A transfer element, in the form of a third coplanar waveguide or a conductive via, is electrically connected to one of the baluns adjacent to, but removed a predetermined distance from, the associated slotline for transferring intermediate oscillator frequency signals. A folded diode ring is connected between the slotlines and to the first and second baluns.

Coplanar waveguide discontinuities for p-i-n diode switches and filter applications

Abstract: A full-wave space-domain integral equation (SDIE) analysis of coplanar waveguide (CPW) two-port discontinuities is presented. An experimental setup to measure the S-parameters of such discontinuities is described. Experimental and theoretical results for CPW realizations of passband and stopband filters are presented. The S-parameters of such structures are plotted in the frequency range 5-25 GHz. >

Coplanar waveguide antenna arrays for MIC/MMIC at millimetre wave frequencies

Abstract: Two kinds of new broadside coplanar waveguide (CPW) antenna arrays are proposed and their performances are confirmed by experiments at a frequency of about 375 GHz They have completely printed structures and can be used in CPW MIC/MMIC operating up to millimetre wave frequencies The array element spacings are appropriate and grating lobes are effectively prevented

Progress Toward MMIC On-wafer Standards

Abstract: A prototype standard set in coplanar waveguide suitable for the calibration of wafer probe stations has been developed through a cooperative effort between the National Institute of Standards and Technology and a MIMIC Phase 3 team. The coplanar standard set is intended primarily for in-process testing, although the characterization of coplanar waveguide circuits is also possible. In this paper two sources of systematic errors associated with the prototype standard set, the propagation of undesirable modes, and the influence of adjacent structures on the electrical connection to the elements of the standard set, will be discussed.