In this letter we propose a novel method of connection, called the hybrid connection, and find that a resistively coupled oscillator with hybrid connection has stable in-phase and anti-phase synchronized oscillations. Averaging method is used to investigate the stability of the synchronized oscillations. The theory is verified by the experimental results.

In this letter, we introduce a predictor based least square (PLS) algorithm. By involving both order- and time-update recursions, the PLS algorithm is found to have a more stable performance compared with the stable version (Version II) of the RLS algorithm shown in Ref.[1]. Nevertheless, the computational requirement is about 50% of that of the RLS algorithm. As an application, the PLS algorithm can be applied to the fast Newton transversal filters (FNTF). The FNTF algorithms suffer from the numerical instability problem if the quantities used for extending the gain vector are computed by using the fast RLS algorithms. By combing the PLS and the FNTF algorithms, we obtain a much more stable performance and a simple algorithm formulation.

A novel nonlinear analysis method of high power amplifier instability has been developed. This analysis method deals with a loop oscillation in a closed loop circuit and presents the conditions for oscillation under large-signal operation by taking account of mixing effect of FETs. Applying this analysis to the high power amplifier instability that an output power for the fundamental wave (f0-wave) decreases at some compression point where a half of the fundamental wave (f0/2-wave) is observed, it has been found that this instability is caused by an f0/2 loop oscillation. In addition, it has been verified by analysis and experiment that the oscillation can be removed by employing an isolation resistor in a closed loop circuit.

A test system with a fuzzy logic controller is proposed to assure stable outgoing quality as well as to raise throughput. The test system controls the number of items under test in accordance with fuzzy information as well as statistical information about incoming quality and outgoing quality. First, an algorithm, minimum-minimum-the center of gravity-weighted mean method, is studied with both fuzzy reasoning rules and membership functions which are used for the control. Second, characteristics of the test system are verified and examined with computer simulations so that the fuzzy logic control rules are determined to realize sufficient sensitivity to process changes. Third, the control rules are installed in the test management processor which commands test equipment for testing very large scale integrated circuits, with programming language C. The authors have obtained satisfactory results through a trial run using a series of lots of 16 bit micro controller units in an IC manufacturing factory. Finally, they study the stability condition of the fuzzy test system.

Current testing has been proposed as an alternative technique for testing fully CMOS digital LSIs. Current testing has higher fault coverage than conventional stuck-at fault (SAF) testing and is more economical because it detects a wide range of faults and requires fewer test vectors than does SAF testing. We have proposed a current testing that measures the integral of the power supply current (IDD) during one clock period including the switching current. Since this method cannot be affected by the switching current, it can be used to test an LSI operating at a relatively high clock freuqnecy. This paper presents an improved current testing method for CMOS digital and analog LSIs. The method uses two current values (i.e., an upper limit and a lower limit) and judges the circuit under test to be faulty if the measured IDD is outside these limits. The proposed current testing is evaluated here for some kinds of faults (e.g., the bridging fault and the breaking fault) in digital and mixed-signal LSIs, and its efficiency of the current testing using SPICE3.

In the final stages of VLSI testing, improved quality VLSI testing is an important subject for ensuring reliability in the forwarded VLSI market. On the other hand, developments in high integration technology have resulted in an increased number of functional blocks in VLSI devices and an increased number of gates for each terminal. Consequently, it has become more difficult to improve the quality of VLSI tests. We have developed a new test method in addition to conventional testing methods intended for improving the test coverage in VLSI tests. This new test method analyzes the relationship between IDDq (Quiescent Power Supply Current) of DUT and DUT failure by applying the concept of the toggle rate. Accordingly, in this paper we report that the results of IDDq testing confirm a correlation with defect level.

In this paper we present a design method for all-pass networks with consideration of the stability. It is based on the eigen filter method and Remez exchange algorithm is used to obtain the equiripple phase error solution. In the iteration of the proposed algorithm, the eigen values besides maximum eigen value are used in order to obtain a stable all-pass networks.

This letter addresses stability problems of interval matrices stemming from robustness issues in control theory. A quick overview is first made pertaining to methods to obtain stability conditions of interval matrices, putting particular emphasis upon one of them, regularity condition approach. Then, making use of this approach, several new stability criteria, for both Hurwitz and Schur stability, are derived.

This paper describes a model of kanji (Chinese characters) learning, called KASTAM (Knowledge Acquisition and STAbility Model), in order to develop a CAI system which supports a student to stabilize her/his kanji knowledge. KASTAM can handle kanji learning as complementary acquisition and stability processes of kanji knowledge.

In this letter we propose a stabilizing method of phase control for resistively coupled oscillator networks. To demonstrate the effect of the control, we consider the coupled oscillator system containing only voltage type of connections. A state feedback technique to resistor sub-network is used to control the phase of synchronized oscillation. The technique is applied to two and three coupled oscillator cases. Finally we present experimental results, which agree well with the theory.

In this study, we investigate the synchronization phenomena of coupled Wien bridge oscillators. The oscillator is characterized by a voltage controlled resistor with saturation. We use linear resistance to couple the oscillators. Two different kinds of coupling techniques, called current and voltage connections are proposed and they show completely opposite mode of synchronized oscillations. The dynamics of the two circuits are also derived to study the amplitude and phase dynamics of the synchronized state. The current connection has a simple resistive effect but stable phase mode is opposite to that of the voltage connection. The voltage connection has the coupling effect which is a combination of resistive and reactive couplings. Coupled three oscillators with current and voltage connection are also studied and stable tri-phase and in-phase synchronizations are observed, respectively. Averaging method is used to investigate the stability of synchronized mode of oscillations. Experimental results are also stated which agree well with the theory.

This paper presents a method, called reduced scan shift, which generates short test sequences for full scan circuits. In this method, scan shift operations can be reduced, i.e., not all but part of flip-flops (FFs) are controlled and observed. This method, unlike partial scan methods, does not decrease fault coverage. In the reduced scan shift, test vectors for the combinational part of a circuit are fistly generated. Since short test sequence will be obtained from the small test vectors set, test compaction techniques are used in the test vector generation. For each test vector in the obtained test set, it is found which FFs should be controlled or observed. And then a scan chain is configured so that FFs more frequently required to be controlled (observed) can be located close to the scan input (output). After the scan chain is configured, the scan shift requirement is examined for the essential faults of each test vector. Essential fault is defined to be a fault which is detected by only one test vector but not other test vectors. The order of test vectors is carefully determined by comparing the scan control requirement of a test vector with the scan observation requirement of another test vector so that unnecessary scan shift operations only for controlling or observing FFs can be reduced. A method of determining the order of test vectors with state transition is additionally described. The effectiveness of the proposed method is shown by the experimental results for benchmark circuits.

It is shown that for a class of interval matrices we can estimate the location of eigenvalues in a very simple way. This class is characterized by the property that eigenvalues of any real linear combination of member matrices are all real and thus includes symmetric interval matrices as a subclass. Upper and lower bounds for each eigenvalue of such a class of interval matrices are provided. This enables us to obtain Hurwitz stability conditions and Schur ones for the class of interval matrices and positive definiteness conditions for symmetric interval matrices.

The stability of a terminated two-port network is investigated, and the stability conditions with only one inequality are obtained. Furthermore, the stability conditions with two inequalities, which are in the same form as those for the passive terminations known at the present time, are also obtained.

Exact analytical solutions for the steady-state transmission and reflection characteristics of a nonlinear Fabry-Perot resonator applicable to bistable optical devices are derived. The resonator consists of a Kerr-like nonlinear film sandwiched by reflection mirrors made of a quarter-wave dielectric stack. An equivalent mirrorless model has been introduced to facilitate the analysis. For both positive and negative nonlinear coefficients, the rigorous solutions have been simply expressed in terms of Jacobian elliptic functions.

This paper proposes a repairable and diagnosable k-valued cellular array. We assume a single fault, i.e., either stuck-at-O fault or stuck-at-(k1) fault of switches occurs in the array. By building in a duplicate column iteratively, when a stuck-at-(k1) fault occurs in the array, the fault never influences the output of the array. That is, we can construct a fault-tolerant array for the stuck-at-(k1) fault. While, for the stuck-at-O fault, the diagnosing method is simple and easy because we don't have to diagnose the stuck-at-(k1) fault. Moreover, our array can be repaired easily for the fault. The comparison with other rectangular arrays shows that our array has advantages for the number of cells and the cost of the fault diagnosis.

In this paper, I investigate a property of self-organizing feature map (SOFM) in terms of reference vector density q(x) when probability density function of input signal fed into SOFM is p(x). Difficulty of general analysis on this property is briefly discussed. Then, I employ an assumption (conformal map assumption) to evaluate this property, and it is shown that for equilibrium state, q(x)p(x)s holds. By giving Lyapunov functioin for time evolution of reference vector density q(x) in SOFM, the equilibrium state is proved to be stable in terms of distribution. Comparison of the result with one which is based on different assumption reveals that there is no unique result of a simple form, such as conjectured by Kohonen. However, as there are cases in which these assumptions hold, these results suggest that we can consider a range of the property of SOFM. On the basis of it, we make comparison on this property between SOFM and fundamental adaptive vector quantization algorithm, in terms of the exponent s of the relation q(x)p(x)s. Difference on this property between SOFM and fundamental adaptive vector quantization algorithm, and propriety of mean squared quantization error for a performance measure of SOFM, are discussed.

The stability conditions and stability factors of terminated active two port networks are investigated. They are expressed with the S parameters of active devices and the radii and centers of the circles defined by source and load terminations. The stability conditions are applied to specific cases. Some of the results correspond to the stability conditions expressed in Z, Y, H or G parameters and one of the other stability conditions of terminated two port network is similar to that for passive terminations which is expressed in S parameters. The various results derived in this paper are very useful for checking the stability of amplifiers, because both stability conditions and stability factors are simply calculated by using the S parameters without using the graphical method or transforming S parameters to Z, Y, H or G parameters. These stability conditions can be also used even if negative input or output resistance appears and even if the real part of source or load immittance is negative.

This paper proposes a new combined fast algorithm for transversal adaptive filters. The fast transversal filter (FTF) algorithm and the normalized LMS (NLMS) are combined in the following way. In the initialization period, the FTF is used to obtain fast convergence. After converging, the algorithm is switched to the NLMS algorithm because the FTF cannot be used for a long time due to its numerical instability. Nonstationary environment, that is, time varying unknown system for instance, is classified into three categories: slow time varying, fast time varying and sudden time varying systems. The NLMS algorithm is applied to the first situation. In the latter two cases, however, the NLMS algorithm cannot provide a good performance. So, the FTF algorithm is selected. Switching between the two algorithms is automatically controlled by using the difference of the MSE sequence. If the difference exceeds a threshold, then the FTF is selected. Other wise, the NLMS is selected. Compared with the RLS algorithm, the proposed combined algorithm needs less computation, while maintaining the same performance. Furthermore, compared with the FTF algorithm, it provides numerically stable operation.

The intensity-dependent transmission characteristics of an Ag+Na+ ion-exchanged glass waveguide with a nematic liquid crystal MBBA cover have been investigated experimentally using an Ar+ laser. It is found that the transmission characteristics of the TE1 mode are strongly influenced by temperature. Optical bistability has been observed at a particular temperature. Such the strong temperature dependence is believed to be brought by an increase in ordinary refractive index of the MBBA cover due to temperature rise.