摘要:

AbstractPiezoelectric resonators with a simple supporting feature have been in demand for numerous applications. In this paper, it is shown that the Lamé modes having vibration nodes at the four corners exist in a rectangular 155° rotated Y‐cut LiNbO3plate with a length‐to‐width ratio of an integer number. The theoretical analysis of equivalent circuit parameters such as capacitance ratio, indicates that this mode can efficiently be excited piezo‐electrically. In addition, it is shown that the experimental results of the impedance characteristic, displacement distribution, and capacitance ratio of the Lamé mode resonators agree with the theoretical results. It is proved that the changes in the resonant frequency and the Q value due to the four corner supports

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790201

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

年代:1996

数据来源: WILEY

摘要:

AbstractThis review paper describes the basic principle of temperature‐compensated quartz oscillators (TCXOs) which are employed extensively in both industrial and consumer electronics.A brief history of quartz oscillators and artificial quartz crystals is given at the beginning followed by a discussion on the recent applications of TCXOs.Direct and indirect methods for compensating the effects of temperature on oscillation frequency in temperature‐compensated crystal oscillators which consume low power and are miniature are then described.In the directly temperature‐compensated crystal oscillators, temperature compensation networks (TCNs) can be either of the serial type or of the parallel type. In this paper, the function of a TCN is described using a parallel‐type network as an example.In the indirectly temperature‐compensated crystal oscillators, the functions of a TCN are discussed separately in high, intermediate and low‐temperature regions. Digitally controlled temperature‐compensated crystal oscillators are also included in this paper as the high‐precision temperature‐compensated crystal oscillators.Some outstanding issues in TCXOs are discussed, and a new type of TCXOs have been proposed to overcome the shortcomings of c

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790202

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

年代:1996

数据来源: WILEY

摘要:

AbstractAs a piezoelectric substrate for surface acoustic wave devices, the LST cut quartz has good temperature characteristics and low propagation loss. However, as the thickness of the metal electrodes on the substrate surface is increased, propagation loss also increases. Further, the electromechanical coupling coefficient is small. In this paper, a cut angle of the quartz substrate is sought that has excellent temperature stability, low propagation loss, and a large electromechanical coupling coefficient in the present of metal electrode films. For the rotated Y‐cut substrate in the neighborhood of the LST cut, the propagating surface acoustic wave (SAW) mode changes from the leaky surface wave to the Love wave‐type surface acoustic wave for which no propagation loss occurs in theory while the electromechanical coupling coefficient increased to 0.5 percent at the maximum if gold is used for the electrodes and the propagation direction of the SAW is shifted from the X axis. This is shown by simulation. By experiment, it is shown that the second‐order temperature coefficient is on the same order as that of the ST‐cut quartz su

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790203

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe difficulty in highly efficient quasi‐phase‐matched second‐harmonic generation (QPM‐SHG) using periodic nonlinear structures is the strictness of the allowance of the period length or the fundamental wavelength in the quasi‐phase matched condition. As a result of these difficulties, the increase of the allowance and the easy fine‐tuning of quasi‐phase matching are very important. In this paper, the fine‐tuning of the quasi‐phase‐matched condition in bulk noncollinear (two‐dimensional) QPM‐SHG by adjusting the angle of incidence of the fundamental wave and by using the Pockels effects by the applied electric field is proposed and its properties are investigated theoretically. For wavelength variations of the fundamental wave, relaxed allowance by automatic readjustment of the angle of incidence using angular dispersions of a diffraction grating is also proposed. The relaxation is adopted in light‐intensity modulation of bulk‐type noncollinear QPM‐SHG, which is achieved by variations in phase‐matched condition by electro‐optic effect. Because nonlinear material, periodic domain inverted LiNbO3is assumed and tuning, relaxation, and modulation characteristics are investigated through numerical simulations. As a result, it is shown that rapid tuning can easily be achieved and the proposed wide wavelength‐band light intensity modulator is expected to realize

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790204

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

年代:1996

数据来源: WILEY

摘要:

AbstractThis paper proposes a high‐pass/lowpass phase shifter with improved reflection and phase‐shift characteristics using resistive matching networks. The circuit configuration, reflection characteristics, phase‐shift error‐reduction methods, and the design results are described. The relationship between the reflection of the single‐pole, double‐throw (SPDT) switch and the phase‐shift error is discussed in the high‐pass/lowpass phase shifter using filters to switch the SPDT switch. The reflection of the SPDT switch caused by the parasitic resistance of the switching device is investigated, and an impedance matching method using the resistive matching networks is proposed to reduce reflection. The calculation results for an S‐band phase shifter with the resistive matching networks show that the matching can be achieved even for switching devices with resistance and that the phase‐shift error can be reduced. An S‐band, 90° single‐bit phase shifter has been designed and a low return loss of better than 19 dB and a phase‐shift error of less than 4° are achieved, which confirms the usefulness of the

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790205

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

年代:1996

数据来源: WILEY

摘要:

AbstractIn this paper, as a method for measurement of complex permittivity of millimeter‐wave dielectric materials, a transmission resonator method is proposed which is made of a dielectric resonator with both sides open placed in a nonradiative dielectric (NRD) guide. For the evaluation of the surface resistance of the conductor indispensable for measurement of the complex permittivity, a pair of TEomlmode resonators are placed coaxially and are mutually coupled. The difference of the conductor losses for the even and odd mode resonances of this resonator system is detected as the difference of the unloaded Q's so that the surface resistance is derived.The special features of the present measurement method are to evaluate the conductor surface resistance at a high sensitivity in a condition close to the resonator with both ends short‐circuited and to use a resonator with both ends open‐circuited for sample measurement because the effect of the surface resistance is small so that high accuracy is obtained as a whole. By using an NRD guide excitation method, a measurement system is realized which affects very little the unloaded Q of the resonator system and the electromagnetic field distribution.For the calculations of the complex permittivity, the eigenvalue calculation by the finite element method and the perturbation method by Kajfez are combined. For the samples with its relative permittivity of 24 and the loss tangent of 2 × 10−4, the measurement fluctuations are less than 0.005 percent for the resonant frequency and less than 1 percent for the unloaded Q. The measurement accuracy for the relative permittivity is less than 0.4 percent and that for the loss tangent is less than 3

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790206

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

年代:1996

数据来源: WILEY

摘要:

AbstractBulk‐type domain reversal gratings of LiTaO3crystal were fabricated at room temperature by the direct electric field method. The nonlinear optical property of the crystal was evaluated by quasi‐phase matching. The period of the bulk‐type domain reversal gratings on an LiTaO3substrate was 7.5 μm and the domain reversal extended to the entire substrate thickness of 500 μm. The experimental normalization efficiency was 0.46 % W cm in second‐order quasi‐phase matching and was close to the theoretical value (0.48%W cm). This result indicates that high‐efficiency nonlinear interaction could be achieved by using the bulk‐type domain reversal grating. The bulk‐type domain reversal grating of nonlinear optical crystal such as LiTaO3is expected to be useful for compact nonlinear optical devices and integra

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790207

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

年代:1996

数据来源: WILEY

摘要:

AbstractA method to enhance nitridation of silicon at low temperature by ultraviolet irradiation is proposed and the nitridation mechanism by this method is discussed. The nitridation of silicon is carried out by irradiating an ultraviolet beam from a low‐pressure mercury lamp on the silicon substrate covered with a thin layer of ammonia. In this method, the attenuation of the ultraviolet beam is small and ammonia is decomposed effectively on the silicon surface. As a result, silicon nitridation is accomplished at a temperature lower by 300°C than in the conventional thermal decomposition method.The nitride film contained a small amount of free oxygen, which is the result from the natural oxide film on the silicon surface and is not introduced during the nitridation process. The silicon nitridation progresses by the diffusion of the nitriding species through the nitride film and the reaction between the nitriding species and silicon on the silicon surface. Both diffusion and reaction are enhanced by ultraviolet irradiation. The active species caused by the decomposition of ammonia by ultraviolet irradiation play an important role in the enhancement of the nitridation. At the same time, the effect of surface excitation by ultraviolet irradiation is not negligib

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790208

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

年代:1996

数据来源: WILEY

摘要:

AbstractThis paper discusses the downsizing and speed improvement of short‐word multiplier‐accumulators, which are frequently used in digital signal processors. As a first step, the optimal configuration for an array‐type carry‐save adder is considered where the shortest path in the full‐adder is used to propagate the sum signal and the carry signal is sent to the full‐adder of the two lower stages by skipping a stage. A configuration of the full‐adder suitable for the structure is proposed. The case of eight partial product additions shows that the delay can be reduced by 22 percent compared to a simple array‐type carry‐save adder. Then the short‐word carry look‐ahead adder using the pass‐transistor logic is considered. It is shown that a single‐stage carry look‐ahead circuit with a four‐bitwise iterative structure exhibits nearly the same delay as a two‐stage carry look‐ahead circuit. In other words, the former is better suited to downsizing. This paper intends to examine the effectiveness of the foregoing new array‐type carry‐save adder and the single‐stage carry look‐ahead circuit using the 0.5‐μm CMOS technology. A 16‐bit X 14‐bit + 31‐bit multiplier‐accumulator has been designed and is evaluated for cases where the array‐type carry‐save adder is used to handle accumulation as well as partial products. The resulting area and delay are 0.77 × 0.78 mm2and 6.8 ns, respectively. The effectiveness of the approach used in this paper is evaluated by constructing a multiplier‐accumulator,

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790209

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe authors previously have reported on the “ring gate delay” system which digitizes the infinitesimal time interval with the delay time of the inverter as the resolution, without using the high‐speed reference clock [1]. A problem then is the improvement of the accuracy since the delay time of the inverter depends on various conditions such as the ambient temperature, the supply voltage, and the fabrication condition. To remedy this point, an LSI is constructed and the delay time of the original circuit is monitored continuously using the quartz oscillation clock of a relatively low frequency as the reference, and the time to be measured is digitized with a high accuracy based on the delay time. In this system, it is not necessary to control the delay time, which makes it possible to utilize the shortest delay time.By a single measurement process using a single input port, up to four pulses can be measured consecutively. If the pulse interval to be measured in less than the specified time, the pulses are combined into a single pulse and an incorrect operation is prevented.In this study, a sample device is constructed by a 1.5‐μm CMOS process. The measurement range of 2200 ns (12 bit) with the time resolution 0.5 ns is achieved using the supply voltage of 5 V. The minimum pulse interval that can be measured is 55 ns (at 25°C). The reference clock used is 2 MHz. The number of transistors is 15, 000 and the chip size is 3.5 mm × 3.8 mm. The constructed LSI is composed totally of digital circuits. The operation is robust against the environmental condition, and a stable operation is realized for the ambient temperature of

ISSN:8756-663X    

DOI:10.1002/ecjb.4420790210

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

年代:1996

数据来源: WILEY