摘要:

AbstractAt present, the devices used in the microwave frequency range are highly dense and employed at higher frequencies as evidenced by MMIC. As these technologies are advanced, the mutual effect between the elements and the loss at the junction between the device and the transmission line affect the device characteristics significantly. Solutions of these problems require studies of the electromagnetic field behaviors such as those between the elements and those at the discontinuities.The authors have used the spatial network method and applied it to a number of problems as a numerical technique for analyzing the three‐dimensional electromagnetic field in the time domain. In the traditional spatial network method, the discretization pitches are identical in all directions. However, due to this limitation, an infinitesimal portion must be divided sufficiently so that the total computer storage capacity increased significantly.In this paper, to resolve this deficiency, a formulation of a new spatial network method is described in which the spatial discretization pitches are arbitrary. The capacitive waveguide window and the fin line are used as examples for the analysis. The validity and effectiveness of the approach are demonstrate

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe characteristics of a two‐dimensional open‐boundary Čerenkov laser consisting of a dielectric‐coated conducting plane waveguide and a planar relativistic electron beam focused with a finite magnetostatic field are investigated theoretically and the following results are obtained.First, the growth rate decreases gradually as the strength of the applied magnetostatic field increases. In particular, the decrease of the growth rate becomes greater around the value of the magnetostatic field for which the electron‐cyclotron frequency is equal to the electron plasma frequency.In addition, the decrease of the growth rate results from the fact that the lowest‐order mode of the space‐charge wave in the absence of magnetostatic field is turned gradually into a mode of the electron‐cyclotron wave as the applied magnetostatic field increases and it finally disappears as the strength of the magnetostatic field tends to infinity. Furthermore, the wave modes propagated along a relativistic electron beam focused with a finite magnetostatic field are generally hybrid or a combination of TE and TM modes. However, the major portion of the electromagnetic energy is carried by TM modes and the contribution of TE modes to energy transport

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractRecently, quantum effect devices have been studied extensively and new functional devices not observed in the conventional devices are expected. As a result, the necessity of developing a design method for superlattices is enhanced.The authors have proposed a method in which the multiple barrier structures are replaced with complex equivalent circuits. Using this method, it is now possible to treat the resonant tunneling effect from the viewpoint of circuit theory. It was shown that the network synthesis theory can be applied to the design of the superlattice. Although the resonant tunneling effect of a double‐barrier structure has been studied extensively for device applications, little attention has been given to the triple‐barrier structures.In this paper, numerical experiments are carried out with this complex‐valued equivalent circuit model so that the resonant conditions of the symmetric triple barrier are studied. To this end, the matching condition valid for a circuit symmetric right to left is applied to the equivalent circuit of a symmetric triple‐barrier structure so that its resonant condition is investigated. It is found that the electron energy that makes the impedance viewed at the center of the equivalent circuit purely resistive is the complete resonant level. It is shown also that this resonant condition can be understood easily by the use of the Smit

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA 40‐Msps 10‐bit video A/D converter LSI has been developed. A 0.8‐μm BiCMOS technology is applied. The two‐step parallel type conversion scheme is adopted, using the MOS analog switch and bipolar comparator. A redundant structure is employed using 5 bits for the coarse stage and 5.5 bits for the fine stage. Three points of voltages in the coarse ladder circuit are transferred to the fine ladder resistor circuit and are used as the upper‐end, middle‐point and lower‐end voltages.Wire connection configuration for the fine ladder resistors is redesigned so that the error is reduced and the speed is improved. A high‐speed circuit with a preamplifier is used in the fine comparator. Protection functions for the overflow and underflow are also provided. With this design, the S/N ratio of 60 dB is realized, for the clock frequency of 40 MHz and the full‐scale 50‐kHz input. The designed LSI operates with the 5‐V single supply. Power consumption is 700 mW, the number of elements is 7000, and the chip size is 4.1 × 4.8 mm2. The following performance is obtained by overall evaluation of the printed board containing the S&H IC and DAC. The D.G. and D.P. for 40‐MHz clock are 1 percent and 1 deg, respectively. The S/N ratio is 52 dB for 10 MHz full‐scale input and 48 dB for 20‐MHz full‐scale input. A future problem involves the on‐chip

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA new driving method (double‐layer simultaneous driving method) is proposed to improve the time multiplexability of compensation‐type homogeneously oriented LCDs by stacking two homogeneously oriented simple matrix LCDs. The experimental results also are shown. Two cells (cell A and cell B) are made of the same LCD material and with the same amount of Δnd. These cells are stacked so that the projected directions of the optical axes onto the electrode surface are perpendicular to each other. By this method, an optical compensation effect can be obtained, and it has enabled good black‐and‐white display.Whereas in the conventional method only one of the two cells is biased, two cells in the proposed double‐layer simultaneous driving method are time‐multiplexed by the optimized bias method with the same duty ratio.During the nonselect state, the rms voltage ofVAB= (Vth·VTmax)1/2is applied. By contrast, during the select state, the rms voltages ofVA=K·VAB/Kare applied to cell A and cell B, respectively. Here,Vthis the threshold voltage,VTmaxis the rms voltage at which the transmission takes the first maximum in theV‐Tcurve during the normally black mode (or the voltage at which the transmission takes the first minimum during the normally white mode), andKindicates {(N1/2+ 1)/(N1/2– 1)}1/2whereNis the number of scanning lines.It has been confirmed that the contrast ratio is improved to 7.5 by the double‐layer simultaneous driving method when the contrast ratio is only 1 when a single layer is driven with the 1/500 duty ratio. Furthermore, the viewing angle characteristics also are improved compared to those of the conventional compensation‐type singl

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractWhen carbon black (CB) with high cohesiveness is used for a carbon‐black resin composite, the temperature coefficient of resin resistivity is negative and the increase in resin resistivity due to humidity is small. These symptoms are due to the balance between the mechanical change, such as thermal expansion and volume increase caused by humidity absorption and the bond strength between CBs. The bond strength between CBs is dependent on curing temperature. In this study, the cohesiveness of CBs which scatter in resin will be investigated by evaluating the electrical property in the high‐frequency region.The impedance of a CB‐resin composite was measured at frequencies up to 3 GHz and was expressed by the parallel equivalent circuit with resistanceRsand static capacitanceCe. Since residual resistance is present at frequencies up to 3 GHz, the equivalent circuit was replaced with the circuit with series resistanceRsand a parallel circuit with resistanceRCand static capacitanceCC. This equivalent circuit was investigated by theSparameter method.As the concentration CB increased,RSandRCrapidly decreased andCCincreased. When CB particles were easily bonded together,RCwas small andCCwas high even if the concentration of CB was low. From the dependencies ofRCandCCon the CB concentration and the temperature dependence of resistance, it was concluded thatRCandCCprovided information on the cohesiveness

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractAn optimization method to achieve good black and white representation in actual driving of phase plate mode STN‐LCDs is proposed. Its effectiveness is confirmed by numerical simulations. In the actual driving, a bias voltage determined by the duty ratio is applied even for the black representation. Therefore, to achieve optimum black and white representation during the actual driving, the film is optimized such that a black representation is obtained for a liquid‐crystal cell under the bias application. For that purpose, the driving voltages must be determined before determining the film condition. Therefore, using the inner product of the complex vectors of the electric field representing two polarizations, optimum driving voltages are determined only from the optical characteristics of the liquid‐crystal cell before the film optimization.Although the film optimization used a method by the Poincaré sphere notation, the wavelength dispersion characteristics of Δndwere also actively optimized. Using numerical simulations, it has been confirmed that good black and white representation with high transmission and good color characteristics can be realized during the actual driving using this optimization

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper studies the transmission characteristics of the microstrip line consisting of a YBCO high temperature superconducting material and investigates the effect of attenuation and distortion of the pulse propagating along such a transmission line. The effectiveness of high temperature superconducting material for interchip and intrachip interconnections is described. Presently, the high temperature superconducting thin film devices are often made on an MgO substrate that has rather high permittivity and a high dielectric loss. Calculation of the characteristics of the transmission line based on the two fluid model is used to demonstrate that the effect of the dielectric loss of the substrate becomes significant at the frequency range below 20 GHz; further, the attenuation constant increases by two orders of magnitude in comparison to the case without the loss caused by the substrate. However, the attenuation constant is smaller than that of the A1 interconnect at 77 K and the phase constant is almost constant independent of frequency so that this transmission line has excellent properties.The distorted wave is derived by simulation when a pulse is applied to this transmission line. It is demonstrated that the line of an MgO substrate at 77 K is superior as a transmission line. On the other hand, a YBCO microstrip line was fabricated on an MgO substrate. The attenuation and phase constants were measured and compared with the theoretical values.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractTo form a thin‐film line‐image sensor with high density and a high‐speed response, an optoelectronic device was fabricated using a gold‐diffused Pb2CrO5thin film; its basic characteristics were evaluated as well. A Pb2CrO5film was deposited using the electron beam evaporation method; this was followed by the deposition of an Au film. The Au was then thermally diffused. As a result, the photoresponse was increased by 150 times, without degrading the spectral response characteristic and the photocurrent/dark current ratio.After Au diffusion, the bias voltage dependence of the photocurrent changed from a parabolic to a linear relationship and the γ coefficient changed from 0.5 to 0.7. In addition, the photoresponse and the transient characteristic in the pulse voltage operation of the Pb2CrO5thin‐film sensor array were improved. It was confirmed experimentally that the resulting device is suitable for high‐speed and high‐de

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractDigital equipment with various high‐speed, low‐power ICs is vulnerable to electrostatic discharge (ESD) and a method to avoid this problem should be developed. Since ESD often is generated by a human while walking, the ESD generating mechanism must be well understood to prevent ESD.This paper proposes a method to estimate the generated charge by evaluating the potential of the human body while walking. Assuming that the basic human motions consist of the up and down movement of the feet, the potential of the human body and generated charges for every step were measured. As a result, it was found that the potential and charges in the human body caused by steps reach a steady state within 800 ms, the potential is lower than 700 V, and the charges are less than 100 nC.The capacitance of the human body changes according to motion and is around 200 pF. When one foot is raised, the body capacitance is 70 percent of that when both feet are grounded. The body potential is dependent on the kind of foot motion, that is, in continuous walk, the body potential is negative and its absolute value increases continuously. In stepping, the potential vibrates with a constant amplitude. These characteristics can be explained from the charging characteristics for the basic body moti

ISSN:8756-663X    

DOI:10.1002/ecjb.4420741210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY