OTA (Operational Transconductance Amplifier) is a useful circuit in analog signal processing systems, especially in high-frequency applications. Important features of OTA are: infinite input impedance, electrically changeable transconductance (Gm), and much wider operation range without negative feedback such as in OPamp applications. The good linearity of OTA over wide input range is necessary to extend the application fields of OTA. Several techniques are developed to extend the input range with good linearity. In this paper, a highly-linear CMOS-OTA operating under 1 V power supply, is proposed. The concept of the proposed OTA is based on class-AB operation of two n-channel MOSFETs in the saturation region. By improving the input stage circuits, wide input range can be achieved. SPICE simulations are performed to verify the performance of the proposed OTA.

The theoretical modelling bandgap narrowing and percentage of ionized impurity atoms for uncompensated uniformly doped silicon containing conventional impurities (B, P, As, Sb) under thermodynamic-equilibrium conditions is presented. As distinct from existing approaches, this modelling is valid for impurity concentrations up to electrically-active-impurity-concentration limits and for the temperature range from 40 K up to 400 K. A relevant and efficient calculation software is proposed. The results of the calculations are compared with the results extracted by many authors from measurement data. A good agreement between these results is noted and possible reasons of some discrepancies are pointed out. The present modelling and software can be used for investigation of BJT charge-neutral regions as well as diffused or implanted resistors.

In this paper, the formulation of unified transport model is reviewed along with its implementation in a three-dimensional device simulator. The model features an accurate description of the energy exchange among electrons, holes and lattice, and is therefore suitable for self-consistently simulating thermal effects and non-stationary phenomena, as well as their possible interactions. Despite the model complexity, it is shown that the computational effort required for its solution is reasonably close to more conventional approaches. Application examples are also given, in which both unipolar and bipolar devices are simulated, discussing the relative importance of different phenomena and highlighting the simultaneous occurrence of carrier and lattice heating.

Tunneling generation becomes increasingly important in modern devices both as a source of leakage and for special applications. Mostly, the observed phenomena are attributed to band-to-band tunneling, although from early investigations of Esaki diodes it is well known that at lower field strengths trap-assisted tunneling is responsible for non-ideal IV-characteristics. In this paper we apply microscopic models of trap-assisted and band-to-band tunneling, which were derived from first-principle quantum-mechanical calculations, in a general multi-device simulator. Special simplified versions of the models were developed for the purpose of fast numerical computations. We investigate pn-junctions with different doping profiles to reveal the relative contribution of the two tunneling mechanisms. Simulated currents as function of voltage and temperature are presented for each individual process varying the basic physical parameters. It turns out that the slope of reverse IV-characteristics dominated by trap-assisted tunneling is similar to those which are determined by band-to-band tunneling, if the localized state of the recombination center is only weakly coupled to the lattice. In the model such a slope is produced by field-enhancement factors of the Shockley-Read-Hall lifetimes expressing the probability of tunneling into (or out of) excited states of the electron-phonon system. The temperature dependence of these field-enhancement factors compensates to a certain extent the expected strong temperature effect of the Shockley-Read-Hall process. The latter remains larger than the temperature variation of phonon-assisted band-to-band tunneling, but not as much as often stated. Consequently, the slope of the IV-characteristics and their temperature dependence are not the strong criteria to distinguish between trap-assisted and band-to-band tunneling. The origin of tunnel currents in silicon rather depends on the sum of physical conditions: junction gradient, nature and concentration of defects, temperature and voltage range.

The increasing size and complexity of integrated circuits has lead to the development of advanced algorithms and techniques for circuit simulation. The majority of circuit simulators rely on the Newton-Raphson algorithm for the solution of nonlinear equations that arise from the circuit description. Unfortunately, a good estimate of the root to be found is needed for the algorithm to converge. The convergence rate of the algorithm is quadratic once the method gets "close enough" to the solution, but before reaching this point the method may follow a complex route through unrealistic values of the circuit variables, leading eventually to divergence. Simulations performed with SPICE on several test circuits reveal that during the first iterations of the Newton-Raphson algorithm internal node voltages exceed the power supply voltage of several orders of magnitudes even for simple circuits. A new simulation program called MUSIC (Multilevel Simulator for Integrated Circuits) has been developed to overcome these drawbacks. In MUSIC the circuit to be simulated is decomposed in subcircuits, which may contain instances of other subcircuits up to any nesting level. Subcircuits are then simulated independently with a multilevel Newton algorithm permitting to reduce both the large oscillations that circuit variables undergo during the simulation process and the number of iterations necessary for the circuit to converge. The novel feature of this multilevel algorithm is the propagation of the already calculated terminal voltages, which become known after a subcircuit has converged, to the subcircuits connected to same terminals. In this way the information regarding node voltages is propagated through the network without constraining conditions that do not have physical counterpart. Simulations performed on chains of inverters and a 4-bit full adder evidence how MUSIC is able to improve the convergence rate and to reduce the intermediate voltage spikes.

Two types of novel nVT level shift circuits based on the square law characteristics of MOSFETs have been proposed. These circuits generate VIN+nVT or VIN-nVT (where VT is a threshold voltage), if the input voltage is applied as the VIN. These circuits can be widely used in MOSFET characterization, compensating VT effect, VT measurement, level shifting, etc. Type 1 is directly derived from the nVT-sift circuit proposed by Wang. Type 2 can reduce a total chip area than type 1 and has a wider input range. SPICE simulations show that the proposed circuits have a very wide input range and a small power consumption.

In 1963, the authors began to develop a tuning circuit (hereafter referred to as the 'circuit') consisting of an inductor, fixed capacitors and a variable capacitor. The circuit required very high accuracy and stability, and the aging influence on resonant frequency needed to be Δf/f0 0.12% for 20 years. When we started, there was no methodology available for designing such a long-term stable circuit, so we reinvestigated our previous studies concerning aging characteristics and formed a design concept. We designed the circuit by bearing in mind that an inductor was subject to natural and stress demagnetization (as indicated by disaccommodation), and assumed that a capacitor changed its characteristics linearly over a logarithmic scale of time. (This assumption was based on short-term test results derived from previous studies.) We measured the aging characteristics of the circuits at room temperature for 20 years, from 1966. The measurement results from the 20-year study revealed that the aging characteristics predicted by the design concept were reasonably accurate.

New focused ion beam (FIB) methods for microscopic cross-sectioning and observation, microscopic crosssectioning and elemental analysis, and aluminum film microstructure observation are presented. The new methods are compared to the conventional methods and the conventional FIB methods, from the four viewpoints such as easiness of analysis, analysis time, spatial resolution, and pinpointing precision. The new FIB methods, as a result, are shown to be the best ones totally judging from the viewpoints shown above.

The crosstalk characteristics of a long-wavelength monolithically integrated photoreceiver array are analyzed. The device consists of an array of transimpedance photoreceivers fabricated on a semi-insulating InP substrate. The distance between the photodetectors is large enough to suppress the photonic crosstalk. Therefore, the crosstalk of the device is mainly due to signal propagation from the channels through the power line shared by each channel on the chip. This crosstalk is inevitable to the photoreceiver arrays which employ common power lines. The magnitude of the crosstalk largely depends on the impedance of the power-supply circuit outside the chip. The crosstalk spectrum often has a peak and recess structure. The crosstalk peak at the edge of the operating band-width is due to the resonance characteristic of the transimpedance amplifier. The other peak and recess structures on the spectrum are due to the resonance phenomena of on-chip and off-chip capacitors and inductance on the power-supply line outside the chip. This crosstalk can be reduced by using on-chip bypass capacitance and dumping resistance. However, the resonance due to the capacitance and inductance on the power-supply circuit outside the chip can't be controlled by the on-chip components. Therefore, an optimized design for the power supply circuit outside the chip is also indispensable for suppressing crosstalk.

In this paper, we present an electronic voting scheme with a single voting center using an anonymous channel. The proposed scheme is a 3-move protocol between each voter and the center, with one extra move if one wants to make objection to the tally. This objection can be broadcasted widely since it will not disclose the vote itself to the other parties besides the center. The main idea in the proposal is that each voter sends anonymously a public key signed by the center and an encrypted vote decryptable using this key. Since even the center cannot modify a received ballot to a different vote using the same public key, the key can be used as an evidence in making open objection to the tally.

Fuzzy control is suitable for automotive control, because fuzzy control achieves controllability as good as control by humankind. However, since automotive control requires milli-second response and learning control, and the fuzzy system in automobiles requires fewer components (built-in type), a custom fuzzy inference LSI is needed for automotive control. We then indicated requirements of a fuzzy inference LSI suitable for automotive control and fabricated a fuzzy inference LSI using 1.5 µm CMOS process technique. This fabricated fuzzy LSI is designed to utilize in various automotive control experiments such as engine control, cruise control, brake control and steering control. The number of input variables is six, the number of output variables is two, the maximum number of production rules is 256, and the inference time is 63 microseconds (under the condition of six inputs, two outputs and 256 rules). The features of the fuzzy LSI are high speed inference, a built-in type, learning control ability and a memory structure separating into a rule memory and a membership function memory. A fuzzy control system is implemented only by the addition of two devices: the fuzzy LSI and an EPROM. The fuzzy LSI was applied to a rough road durability test aiming at the automatic driving equivalent to the human driver operation. In the test, fuzzy control and linear control were compared in terms of the compensation steering degrees. Linear steering control had a high rate of compensation steering of less than thirty degrees. On the other hand, the accumulated steering compensation of less than twenty degrees in the fuzzy control was about one third that in the linear control. The fuzzy steering control had the same steering compensations as that of human steering. The fuzzy LSI fabricated for various experiments is too large (10.7 mm10.9 mm) to adopt as automotive parts. Therefore, we studied a smaller-sized fuzzy LSI by limiting functions, by changing the parallel processing into sequential processing and by thinning out the memory data of input membership functions. The number of input variables is four, the number of output variables is two, the maximum number of production rules is 160 and the expected inference time is 140 micro-seconds (in the worst case). The obtained chip is small enough (4.8 mm4.8 mm) for automotive applications. Since the chip contains all the memories that are needed to execute fuzzy inference, the chip can be built in a microprocessor as a fuzzy inference co-processor without any other circuits.

Two types of circuit architecture for GaAs LSI are described. The first circuit is named Stacked DCFL which has supply voltage compatibility with Si CMOS/BiCMOS and ECL operating on 3 V or 3.3 V. A divide by 128/129 prescaler IC has been developed to confirm the Stacked DCFL circuit operation. The second circuit is named SVFL which operates on single supply voltage by using Schottky FET characteristics in spite of normally-on FET logic. Both circuit architectures are based on the virtual ground concept. The transition time of 45 psec was obtained by the SVFL ring oscillator circuit fabricated with 1 µm gate length FET process, and the transition time of DCFL using the same process was from 80 psec to 100 psec. Stacked DCFL and SVFL are candidates for an internal gate and an input/output interface circuit for GaAs ASIC, respectively.

The technical trends of intelligent vehicles are discussed basing on the progress of technology of microelectronics, sensing and information processing. The concept of intelligent vehicles has started when the installation of computers on vehicles became possible in 1970s. The functions of computerized cars increased gradually with the progress of technology of microelectronics, sensing and information processing responding to the demands of the society. The first issues we had to challenge with the capability of electronic systems were the environmental and the energy resources problems. The R & D works of these purposes created many sophisticated computer control systems. Moreover, these works established the base of intelligent vehicles that contains various functions for drivability, safety, and information communications. On the other hand, many kinds of information and communication technology became useful to solve the issues on automobiles through infrastructure systems. United States, Europe, and Japan have started their own projects to realize such hierarchy management systems for traffic and vehicles. From the viewpoint of vehicle itself, it is the indispensable conditions and directions to implement the computer and telecommunications functions to the vehicles to establish clean, comfort, convenient, efficient and safe automobiles toward the next century.

The potential distribution around a linear array of donor atoms in a semiconductor crystal is calculated, approximating the linear array by a continuous line charge. Two methods are used for the analysis. One is the self-consistent calculation of Poisson's equation and the effective mass Schrödinger's equation, and the other is the Thomas-Fermi approximation. Results of both methods agree very well, and it is shown that it is possible to form a potential distribution as fine as the electron wavelength by appropriate arrangement of the impurity atoms. Arrays of impurity atoms therefore can act as buiding elements for future electron wave devices.

This paper describes our recent developments of ASICs for automotive multiplexing and data communications to implement in-vehicle networks. With the advancement of automotive electronics, there are ever growing needs for in-vehicle networks. One need is associated with solving the problem of an increasing number of electrical signal wires that inevitably accompany the increasing applications of automotive electronics. Another kind of need is concerned with sharing vehicle control data among several electronic control units such as engine, brake, suspension, and steering electronic control units to achieve an integrated vehicle control system for the purpose of obtaining higher performances in vehicle dynamics. In order to reduce the number of signal wires and share the control data, in-vehicle networks based on multiplexing and data communications are required. In this paper, two original communication protocols are presented to respectively cover low- and highi-speed multiplexing and data communications that are two most needed communication speed areas in our present and future automobiles. ASICs for the presented communication protoclos were designed and fabricated, using 2 µm COMS process. They have the chip size of 3.2 mm2.7 mm with 5,000 transistors and 6.9 mm4.9 mm with 18,000 transistors respectively for low- and high-speed multiplexing and data communications. An elaborate bus driver/receiver ASIC required for high-speed multiplexing and data communications was also designed and fabricated, using 35 V DC bipolar process. As one of its distinctive features, it can greatly suppress radio frequency noise radiated from a communication bus. It has the chip size of 4.8 mm3.8 mm that contains 570 device elements. The features of the protocols are given in detail with the descriptions of the developed ASICs.

Electronics and automobiles were bound together by the introduction of emission regulations in the 1970's. The rapid progress of control technology and semiconductors that typify microcomputers has brought still closer relations between them. Without electronics, it would be impossible to realize features such as pursuit of comfort and environmental and safety measures which should be added to the automobile's fundamental features. In looking ahead to the future, the role of electronics in achieving electric automobiles and the ultimate goal of "automatic driving" is ever-increasing. Everyone knows that automobiles have become indispensable in our lives. In the future, the role of electronics will become increasingly important in order to evolve automobiles even further to allow harmonization with society.

A communication LSI Set for Automotive Body control systems such as power windows, power seats, and power doors based on an in-vehicle network have been developed. The main function of the LSI is to achieve an original automotive communication protocol. The LSI set makes it possible to build a new kind of automotive control system, and reduces the number of wiring harnesses and weight below those of the conventional automotive body electronics. The communications transmitters and receivers have been integrated on-chip, so the LSI needs several external discrete components such as resistors, capacitors, and diodes. This communications LSI offers the advantages of small size and high reliability of the electronic control unit based on an in-vehicle network.

Four circuit techniques and a layout design scheme were proposed to realize a 2 Mb VRAM used 0.8 µm technology. They are the enhanced circuit technologies for high speed operation, the functional circuit design and the effective repair schemes for a VRAM, the low power consumption techniques to active and standby mode and a careful layout design scheme realizing high noise immunity. Using these design techniques, a 2 Mb VRAM is suitable for the graphics application of a 5125128 pixels basis screen, with a clear mode of 4.6 GByte/sec and a 4-multi column write mode of 400 MByte/sec, even using the same 0.8 µm technology as the previous VRAM (1 Mb) was realized.

To make a fast Bi-CMOS SRAM yield high without speed degradation, three defect-repair methods, the address comparison method, the fuse decoder method and the distributed fuse method, were considered in detail and their advantages and disadvantages were made clear. The distributed fuse method is demonstrated to be further improved by a built-in fuse word driver and a built-in fuse column selector, and fuse analog switches. This enhanced distributed fuse scheme was examined in a fast Bi-CMOS SRAM. A maximun access time of 14 ns and a chip size of 8.8 mm17.4 mm are expected for a 4 Mb Bi-CMOS SRAM in the future.

The characteristics of an open-boundary Cherenkov laser for an electromagnetic wave with a continuous frequency spectrum are numerically analyzed. A given power spectral density for the input wave is found to get concentrated around the frequency where the spatial growth rate is maximum, as it grows along the electron beam. In addition, the frequency for the maximum growth rate is found to shift gradually to higher values. Furthermore, by gradually increasing the permittivity of the dielectric waveguide along it, we can always get the maximum power spectral density at the frequency where the spatial growth rate initially becomes maximum at the input.