摘要:

AbstractIt is necessary to increase the density of fibers of optical cables which are to be used in subscriber lines. To realize such high‐density fiber cables, multicore fibers with several cores inside a single cladding have been investigated. However, in multicore fibers, there is the problem of crosstalk between the adjacent cores.This paper investigates the two‐core asymmetric single‐mode fibers which reduce the crosstalk between adjacent cores. It is shown numerically that the crosstalk can be kept below a certain level for any fiber length, under the condition of fixed‐mode field diameter. In a symmetrical structure, the transfer of optical power is perfect and to suppress the crosstalk, the transmission length must be kept limited. However, in asymmetrical structures investigated in this paper, the transmission length is not limited and it becomes possible to design high‐density optical transmission lines with small separation between their

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750301

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

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper describes a shielded‐velocity‐matched Ti:LiNbO3optical modulator which realizes a wide bandwidth with the velocity matching between the optical wave and the modulation microwave by placing a shielding conductor close to the coplanar waveguide traveling electrode through an air overlay.In the design of the traveling‐wave electrode, a quasi‐TEM approximation and a spectral domain approach with hybrid mode are used. From numerical analysis it has been found that the effective refractive indices of the microwave and the light wave can be matched by optimally setting the overlay thickness. It has also been found that the increase in the microwave propagation loss or decrease in the characteristic impedance can be suppressed by increasing the thickness of the SiO2buffer layer. As for the optical waveguide, the design parameters have been clarified by using a newly developed modified step segment method.Based on these examinations, a Mach‐Zehnder intensity modulator and a phase modulator for the 1.5‐μm wavelength band have been designed and fabricated. As a result of measurement, the optical modulation bandwidth has been improved greatly to 20 GHz. As for the drive voltage, the intensity modulator uses 4.7 V and the phase modulator uses 6 V. The total insertion loss including the connector loss is 2.2 dB for the intensity modulator and 2 dB for the phase modulator. It has also been verified that the modulators have superior ambie

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750302

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

年代:1992

数据来源: WILEY

摘要:

AbstractIt is shown that even if the modulating frequency of a light is too high for direct detection, the signal can be extracted by frequency conversion at the same time as the detection by means of the nonlinearity of the APD. When this frequency conversion detection is applied to an optical receiver, the detection bandwidth can be increased while the configuration of the optical detection circuit and the signal processing in the subsequent stages are simplified. A fundamental analysis is carried out with an APD which is confirmed experimentally.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750303

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe transfer splicing of optical fiber cables is performed at night using released circuits; this involves time‐consuming manual work. To achieve highly efficient optical cable transfer splicings, development of low‐loss transfer components is expected to speed up transfer operations. This in turn reduces interruption time and identification of cable fibers and also controls synchronization of each function and details required.This paper proposes an efficient system for the optical transfer splicing of the existing cables to the new ones. This system uses single‐mode multifiber connectors. The design method and related details of rapid transfer, fiber identification and synchronous transfer control are described. The transfer splicing characteristics of this newer, more efficient system are evaluated and it is verified experimentally that satisfactory results are pos

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750304

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe phase‐locked loop (PLL) circuit used in the timing recovery of high‐speed digital communications and high‐density digital recordings must have a fast pull‐in time and low jitter. One way to satisfy both characteristics is to use a two‐mode PLL in which the loop gain is switched in the pull‐in state and the steady state. However, in the PLL with a conventional procedure, the time constant of the loop filter cannot be reduced in the pull‐in state; hence the time for phase locking after frequency locking cannot be reduced.This paper proposes a method in which the time constant of the loop filter and the loop gain are both switched. The loop gain is switched by the gain of the smoothing filter to eliminate ripple in the output from the phase comparator while the time constant is switched by the resistor in the loop filter. This method realizes a pull‐in time one‐tenth that in the PLL with conventional two‐mode operation.A PLL IC using the forementioned method was fabricated by 2‐μm BiCMOS process technology. Its capture range was ±2 percent, the pull‐in time was 100 μs, and the noise bandwidth was 1

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750305

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

年代:1992

数据来源: WILEY

摘要:

AbstractIn realizing the intelligent sensor which flexibly transforms input information into the information required by the user employing such knowledge processing as fuzzy inference, the following points are especially important: (1) the representation of the knowledge as well as the acquisition of the knowledge should be easy; and (2) the inference should be executed with a high speed.This paper proposes a sensor construction which satisfies both of the forementioned requirements. The intelligent sensor proposed in this paper employs the if‐then type knowledge representation as the fuzzy rule with a high affinity to human thought. The sensor is composed of three independent neural nets: the input (if) part, the output (then part), and the input/output relation (if‐then) part.In the input part, the learning vector quantization (LVQ) network evaluates the features of the input waveform, and the result is mapped directly on the concept represented in the condition part of the fuzzy rule. LVQ executes self‐learning without a supervisor based on the features of the input waveform and automatically generates the membership function needed in the condition part of the fuzzy rule. This simplifies the knowledge acquisition process.In the input/output relation part, the fuzzy inference is executed with a high speed by the parallel processing of the associative memory network. Thus, the intelligent sensor based on the fuzzy associative memory can improve the forementioned two points (1) and (2). Furthermore, to demonstrate the high versatility of the proposed construction, this paper considers the problem in which two entirely different sample problems are realized by the same construction. The realization example is shown by a simul

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750306

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

年代:1992

数据来源: WILEY

摘要:

AbstractA monolithic integrated magnetic sensor realizing omnidirectional measurement is presented. This monolithic integrated sensor consists of three Hall cells which detect magnetic components inx,y, andzdirections and the bipolar circuit which converts the output signal of Hall cellsVX,VY, andVZinto its absolute value (=(V2X+V2Y+V2Z)1/2).For the magnetic detector, a new “lateral Hall cell” is proposed to detect the magnetic components parallel to the chip surface (x,ydirections). The three‐dimensional (3‐D) magnetic detection has been realized by combining two lateral Hall cells and a conventional epitaxial (lateral) Hall cell (forzdirection).The signal conversion circuit uses a Gilbert multiplier for square calculation and a translinear circuit for a root circuit, with a total device count of 158 elements. The test device realized an omnidirectional magnetic measurement with a maximum error of ±4 percent, sensitivity of 14 V/T, and a temperature coefficient of 2100 ppm/°C in the magnetic flux range of −250

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750307

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

年代:1992

数据来源: WILEY

摘要:

AbstractTwo types of scanning systems usingN‐ary tree structures are proposed for high‐speed intelligent processing in an SIMD parallel processor. The scanning systems are constructed by connecting operating elements to each other with hierarchical bypasses or hierarchical and selective propagation paths. After evaluating their operating times, the amount of hardware, and LSI implementation, the following conclusions were reached: (1) the number of serially operating elements in the propagation path is onlyO(NlogNM); (2) enlarging theN‐value decreases the amount of hardware; (3) the selective‐type scanning system is twice as fast as the bypass‐type system although both require almost the same amount of hardware; and (4) a 42‐ary tree structure leads to a simple and dense

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750308

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe traditional neural system which conducts the paired association has the real coupling coefficients and is not suited to the implementation on digital processing LSI because of its analog property.From such a viewpoint, this paper applies the traditional idea of calculating the coupling coefficients on the real field to the binary field and proposes a system which conducts the paired association using only the logic operation. More precisely, it is noted that the associative law applies to the matrix operation on the real field as well as the matrix operation for the binary code.The coupling coefficients for the binary code for the paired association are derived by applying the sweeping‐out method to the matrix of binary numbers. By this approach, a paired‐associate system is obtained by a simpler training algorithm with easy LSI implementation.This paper describes first the traditional solution of the paired‐associate problem on the real field and then proposes a method of solution based on that approach for the paired‐associate problem on the binary field. The existence condition for the solution of the paired‐associate problem is discussed for the proposed method. Finally, the noise‐reduction power of the proposed method i

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750309

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

年代:1992

数据来源: WILEY

摘要:

AbstractBiCMOS SRAM has high speed comparable to that of the bipolar ECL RAM. In the realization of the SRAM by previous technology, the useful SRAM architecture employs the bipolar current switching circuit for all the peripheral circuits and CMOS for the cell array.This paper discusses the construction of the bipolar peripheral circuit to apply the forementioned architecture to large‐capacity memory. First, the decoding scheme using the emitter‐follower is proposed for the selector circuit which contains the bipolar current switching circuit and the selection function. It is shown that the delay time and the power consumption can be suppressed even if the memory capacity is increased. The word driver which employs the current switching level converter and the CMOS converter is proposed. The relation between the current of the level converter and the inverter size is clearly indicated, and it is shown that a high‐speed operation is realized. Then the three‐stage multiplexer is proposed for the read‐out circuit. where the output buffer is provided with the selection function. The number of multiplexing in each stage is determined which minimizes the delay time of the read‐out circuit. Finally, the proposed structure is applied to the 256‐kbit SRAM and the usefulness is

ISSN:8756-663X    

DOI:10.1002/ecjb.4420750310

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

年代:1992

数据来源: WILEY