An efficient algorithm is proposed for finding all solutions of piecewise-linear resistive circuits The algorithm is based on the idea of "contraction" of the solution domain using a sign test. The proposed algorithm is efficient because many large super-regions containing no solution are eliminated in early steps.

In order to apply formal design verification, it is necessary to describe formally and correctly the specification of the circuit under verification. Especially when we apply conventional OBDD-based logic comparison method for verifying combinational circuits, another correct" logic circuits or Boolean formulae must be given as the specification. It is desired to develop an efficient automatic design verification method which interprets specification that can be described easier. This paper provides a new verification method which is useful for combinational circuits such as arithmetic circuits. The proposed method efficiently verifies whether a designed circuit satisfies a specification given by recurrence equations. This enables us to describe easily an error-free specification for arithmetic circuits. To perform verification efficiently using an ordinary OBDD package, an efficient truth-value rotation algorithm is developed. The truthvalue rotation algorithm efficiently generates an OBDD representing f(x + 1 (mod 2n)) from a given OBDD representing f(x). By experiments on SPARC station 10 model 51, it takes 180 secs to generate an OBDD for designed circuit of 23-bit square function, and additional 60 secs is sufficient to finish verifying that it satisfies the specification given by recurrence equations.

The author once defined the Ω-matrix and showed that it played an important role for estimating the number of solutions of a resistive circuit containing active elements such as CCCS's. The Ω-matlix is a generalization of the wellknown P-matrix. This paper gives the necessary and sufficient conditions for the Ω-matrix.

In this paper, Chay's bursting pancreatic β-cell model is updated to include a role for [Ca2+]ER, the luminal calcium concentration in the endoplasmic reticulum (ER). The model contains a calcium current which is activated by voltage and inactivated by [Ca2+]i. It also contains a cationic nonselective current (INS) that is activated by depletion of luminal Ca2+ in the ER. In this model, [Ca2+]ER oscillates slowly, and this slow dynamic drives electrical bursting and the [Ca2+]i oscillations. This model is capable of providing answers to some puzzling phenomena,which the previous models could not (e. g., why do single pancreatic β-cells burst with a low frequency while the cells in an islet burst with a much higher frequency ?). Verification of the model prediction that [Ca2+]ER is a primary oscillator that drives electrical bursting and [Ca2+]i oscillations in pancreatic β-cells awaits experimental testing. Experiments using fluorescent dyes such as mag-fura-2-AM could provide relevant information.

In this paper, after the introduction of the definition of State Controlled Cellular Neural Networks (SC-CNNs), it is shown that they are able to generate complex dynamics of circuits showing strange behaviour. Theoretical propoitions are presented to fix the templates of the SC-CNNs in such a way as to exactly match the dynamic behaviour of the circuits considered. The easy and cheap implementation of the proposed SC-CNN devices is illustrated and a gallery of experimentally obtained strange attractors are shown to confirm the practical suitability of the outlined strategy.

In order to improve the sensitivity of micromachined sensors applied with electrostatic fields and increase their actuated force of electrostatic micromachined actuators, "electrets," which are dielectrics carrying non equilibrium permanent space charges of polarization distribution, are very important. In this paper, positively corona charged silicon dioxide electrets, which are deposited by Plasma Chemical Vapor Deposition (PCVD) and thermally oxidized, are investigated. Physical studies will be described, in which the charge stability is correlated to Thermally Stimulated Current (TSC) measurements and to Electron Spin Resonance (ESR) analysis. Some intrinsic differences have been observed between materials. The electrets with superior long-term charge stability contain 10,000 times as much E' center (Si3 as the ones with inferior long-term charge stability. Finally, some investigations on the long-term charge storage mechanism of the positively charged silicon dioxide electret will be described.

A high-frequency approximate method for calculating the diffraction by a smooth convex surface is presented. The advantage of this method is the validity of it in the caustic region of the creeping rays where the Geometrical Theory of Diffraction (GTD) becomes invalid. The concept used in this method is based on the Method of Equivalent Edge Currents (EEC), and the equivalent line currents for creeping rays which are derived from the diffraction coefficients of the GTD are used. By evaluating the radiation integral of these equivalent line currents, the creeping ray contribution which is valid within the caustic region is obtained. In order to check the accuracy and the validity of the method, the diffraction problem by a perfectly conducting sphere of radius a is solved by applying the method, and the obtained results are compared with the exact and the GTD solutions. It is confirmed from the comparison that the failure of the GTD near the caustic is removed in this method and accurate solution is obtained in this area for high-frequency (ka8). Furthermore, it is also found that this method is valid in the backward region (0θ90, θ is an observation angle mesuered from an incident direction), whereas not in the forward region (90θ180).

This paper describes a narrow pass-band optical filter utilizing a wavelength-sensitive power-transfer characteristic in the directional coupler composed of the K-and Ag-ion exchange waveguides which have greatly different dispersion relations caused by the large mismatch in the index profile of the waveguide cross-section. A narrow pass-band width of about 7 nm is measured in the filter fabricated in the soda-lime glass substrate. The fabrication technique with two-step ion-exchange of the K-and Ag-ions, is also presented together with a quick design method.

This paper presents the scattering characteristics of a TE electromagnetic plane wave by metallic strip gratings on an optically plasma-induced silicon slab at millimeter wave frequencies. The characteristics were analyzed by using the spectral domain Galerkin method and estimated numerically. We examined to control the resonance anomaly by changing the optically induced plasma density, and the metallic strip grating structures were fabricated on highly resistive silicon. The optical control characteristics of the reflection, and the forward scattering pattern by the grating structures, were measured at Q band and are discussed briefly with theory.

The problem of electromagnetic scattering by capacitive discontinuities located in rectangular waveguides, in particular when dealing with discontinuous conductors of finite thickness, is analyzed using the modified residue-calculus method, and form of the equation suitable for a numerical calculation is derived. The incident wave is taken to be the dominant mode, and reflection and transmission properties of an asymmetric capacitive iris are discussed. After the modal representation of the filed, the modal matching is apply to satisfy the boundary conditions at the discontinuity. And using the modified residue-calculus method, simultaneous infinite equations, which are concerned with the scattered mode coefficients, are derived. Then they are approximated at the thick diaphragm. The solutions obtained take on the form of an infinite product, and a numerical solution based on the method of successive approximations is presented as a technique for concretely determining the reflection coefficients. As confirmation, experiments are also carried out in the X-band and close agreement is shown between the calculated and experimental values.

Hot-carrier degradation of voltage controlled oscillator (VCO) was investigated by a reliability simulator known as BERT. The appropriate monitor of VCO frequency degradation shifts from the saturated drain current of an N MOSFET to linear drain current with an increase in VCO input voltage. The degradation of the VCO drastically increases with a small reduction in initial oscillation frequency. These results imply the need for an appropriate reliability margin around the standard operating point as well as a performance margin, which cannot be achieved by using conventional drain current monitors.

The 4th harmonics of a Nd:YAG laser beam (266 nm) is applied to fabricate highly oriented Y1Ba2Cu3O7-δ -SrTiO3-Y1Ba2Cu3O7-δ multilayer structures. It has been shown that the emission temperature of a film surface will change during deposition, depending on deposition conditions, even though the heater temperature is constant. The change of substrate temperature is strongly correlated to film characteristics such as critical temperature, c-axis length, and resistivity. The insitu monitoring of the substrate temperature is useful for obtaining high-quality Y1Ba2Cu3O7-δ films reproducibly. It is also shown that a SrTiO3 layer prevents oxygen restoration in a Y1Ba2Cu3O7-δ underlayer. The relationship between oxygen deficiency and the annealing conditions is studied.

In the weakly coupled grain model which has been proposed to explain the residual surface resistance in high-Tc superconducting polycrystalline thin films, the superconducting polycrystalline thin films is described as a network of superconducting grains coupled via Josephson junctions. In order to evaluate this model we have fabricated the coplanar waveguide resonator using c-axis oriented YBa2Cu3Ox Thin Films and measured the residual surface resistance. The experimental results are in good agreement with theoretical prediction.

A quasi-optical Superconductor-Insulator-Superconductor (SIS) mixer has been designed and tested in the 270-GHz band. The mixer used a substrate-lens-coupled log-periodic antenna and a tuning circuit for RF matching. The antenna is planar and self-complementary, and has a frequency-independent impedance of around 114 Ω over several octaves. The tuning circuit consists of two Nb/AIOx/Nb tunnel junctions separated by inductance for tuning out the junction capacitances and a λ/4 impedance transformer for matching the resistance of the two-junction circuit to the antenna impedance. The IF output from the mixer is brought out in a balanced method at each edge of the antenna, and is coupled to a low noise amplifier through a balun transformer using a 180-degree hybrid coupler for broadband IF matching. Double sideband receiver noise temperatures, determined from experimental Y-factor measurements, are about 150 K across the majority of the desired operating frequency band. The minimum receiver noise temperature of 120 K was measured at 263 GHz, which is as low as that of waveguide receivers. At this frequency, measurement of the noise contribution to the receiver results in input losses of 90 K, mixer noise of 17 K, and multiplied IF noise of 13 K. We found that the major sources of noise in our quasi-optical receiver were the optical losses.

A binary counter circuit in the extended phase-mode logic (EPL) family is presented. The EPL family utilizes a single flux quantum as an information bit carrier. Numerical simulations show that a binary counter circuit with a Josephson critical current density of 1 kA/cm2 can operate up to a 30 GHz input signal. The circuit has been fabricated using Nb/AlOx/Nb Josephson junction technology. New interface circuits are employed in the fabricated chip. A low speed test result shows the correct operation of the binary counter.

This paper presents a configuration of circularly polarized annular-ring microstrip antenna (ARMSA) and its design method to obtain high gain and low axial ratio including the analysis of finite ground plane effect using G.T.D. for personal satellite communication use. The ARMSA excited at TM21 mode through co-planar branch-line hybrid coupler for circular polarization produces a conical pattern which has high gain in low elevation angle. The relation of gain and axial ratio versus the dielectric constant of substrate are shown and the existence of the dielectric constant which satisfies two requirements, that is, high gain and low axial ratio are clarified. For car-top application, experimental results in the L-band showed satisfactory characteristics for vehicle antenna.

M-ary orthogonal keying (MOK) systems under carrier frequency offset (CFO) are investigated. It is shown that spurious signals are introduced by the offset frequency components of spectrum after multiplication in correlation detection process, and some conditions on robust orthogonal signal sets are derived. Walsh function sets are found to be very weak against CFO, since they produce large spurious signals. As robust orthogonal signal sets against CFO, the rows of circulant Hadamard matrices are proposed and their error performanses are evaluated. The results show that they are good M-ary orthogonal signal sets in the presence of CFO.

A close correlation between the YBa2Cu3Oy film morphology and location of the (100) MgO substrate during growth by excimer laser ablation was obtained. When the susbtrate was placed inside the fringe portion of the laser plume, the spiral shape was most clearly seen on the entire film surface for both the conventional and eclipse ablation methods. When the substrate was placed outside the plume, the spiral growth was less pronounced. On the other hand, when the substrate was placed inside the plume core, marked deformation of the morphology occurred, and the superconducting critical temperature was lowered. This correlation was explained to some extent by the spatial variation of kinetic energy of the flying growth species.

Recently, the high-speed data transmission techniques that have been developed for communication systems have in turn necessitated the implementation of high-speed error correction circuits. Parallel processing has been found to be an effective method of speeding up operarions, since the maximum achievable clock frequency is generally bounded by the physical constraints of the circuit. This paper presents a parallel encoder and decoder architecture which can be applied to both binary and nonbinary cyclic codes. The architecture allows H symbols to be processed in parallel, where H is an arbitrary integer, although its hardware complexity is not proportional to the number of parallel symbols H. As an example, we investigate hardware complexity for a Reed-Solomon code and a binary BCH code. It is shown that both the hardware complexity and the delay for a parallel circuit is much less than that with the parallel operation of H conventional circuits. Although the only problem with this parallel architecture is that the encoder's critical path length increases with H, the proposed architecture is more efficient than a setup using H conventional circuits for high data rate applications. It is also suggested that a parallel Reed-Solomon encoder and decoder, which can keep up with optical transmission rates, i.e., several giga bits/sec, could be implemented on one LSI chip using current CMOS technology.

Cutoff rate of overlapping multi-pulse pulse position modulation (OMPPM) is analyzed in the quantum-limited and the background noise cases. Our results suggest that the derived cutoff rate is higher than conventional one because of the infinite quantization at the demodulator and the definition of the erasure event in conventional analysis.