bluuebunny/crossref_metadata_2025_split huggingface dataset:
A design of automatically tunable active MOSFET‐RC filters using a single‐ended circuit structure
Authors: Inoue Takahiro , Ueno Fumio , Sonobe Satoru , Kawasaki Mikio 
Published: July 2007

AbstractRecently, as a new continuous‐time filter, an automatic tuning MOSFET‐C filter was proposed by Banu and Tsividis. It consists of MOSFETs, capacitors and operational amplifiers. It was shown that a highly accurate filter can be realized. In this configuration, only the voltage‐variable MOSFET resistor is used as the resistor and its non‐linearity is eliminated by a circuit configuration such as a fully balanced type.This paper proposes an active MOSFET‐RC filter in which elimination of the nonlinearity of the MOSFET resistor does not require matching between MOSFETs. The filter consists of MOSFETs, capacitors, linear resistors with identical values and operational amplifiers, and can be made of a single‐ended circuit.An automatic tuning of the filter characteristics is possible via a control of the resistance value of the MOSFET resistor with a PLL made of a voltage‐controlled all‐pass filter. Based on this configuration, a third‐order elliptic low‐pass filter was constructed with discrete components. With a power supply voltage of ±5 V, the filter characteristics were a total harmonic distortion of less than 0.1 percent, a dynamic range of more than 110 dB, and a passband gain variation of less than ±0.1 dB in the temperature range of −20°C to 80°C for a filter input voltage of less than 5.3 Vp−p.
A design method for coherent optical fiber filters of direct form
Authors: Lee Chae‐Wook , Sakaniwa Kohichi 
Published: July 2007

AbstractRecently, optical signal processing has attracted considerable attention for highspeed and broadband signal processing such as channel separation filtering for optical FDM signals.This paper considers coherent optical fiber filters which use coherent light sources and consist of directional couplers and optical fiber delay elements. These optical fiber filters are permitted to have both positive and negative value for filter coefficients, but still differ from the usual digital filters, since in the optical fiber filters, (1) the coupling coefficient a of a directional coupler is restricted to the value between 0 and 1, (2) optical signal E (complex amplitude) is divided into j√a E and √1‐aE at the directional coupler, and (3) for input signal E1 and E2, the output of a directional coupler is given by √1‐aE1 + j√a E2.Considering these restrictions, we clarify the realizability condition and establish the optimal design method for optical fiber filters of direct form which make best use of optical signal energy.
An estimation method of the pairing and ordering for IIR digital filters with low roundoff noise
Authors: Oguro Yoshinari , Yoshikawa Toshinori 
Published: July 2007

AbstractThis paper considers the IIR cascade digital filter based on the fixed‐point arithmetic, and presents a method for estimation of the optimal pairing and ordering to minimize the output roundoff noise. In the proposed method, the computational complexity required in the estimation is reduced by considering only the pole frequencies of the transfer function in the evaluation. In the scaling of each branch node, the general L2 ‐ and L∞‐norms are assumed.The proposed method is compared with the methods of Jackson, Lee and Liu‐Peled which are used frequently in practice. The four methods are applied actually to two kinds of filters, and the computational complexities are compared. It is shown as a result that the proposed method requires almost the same computational complexity as those of Jackson and Lee from the lower‐order to higher‐order filters, and realizes the pairing and ordering with smaller output roundoff noise. It is shown also in general that the pairing has a larger effect on the normalized output roundoff noise than the ordering.
Improvement of linearity in switched resistors
Authors: Fukai Sumio , Ishikawa Hirobumi 
Published: July 2007

AbstractSwitched resistor circuits have been proposed as a realization of equivalent resistors suitable for monolithic integrations. Since the linear resistance region of an MOSFET has been used, the dynamic range of the signal handled has been small. This paper presents methods for improving the linearity of the MOSFET suitable for a switched resistor circuit. With a view to configurations with fewer circuit elements, a method is considered for feedback from the drain to the gate and a method in which the nonlinearity is cancelled with two matched MOSFETs. It is confirmed experimentally that a practical dynamic range can be obtained and a high resistance can easily be realized with these methods for improvement.
Mixed D‐A circuit simulation by one‐way subcircuit time‐first analysis approach
Authors: Kage Tetsuro , Shimogori Shintaro 
Published: July 2007

AbstractThis paper considers the mixed digital‐analog (D‐A) circuit which contains both logic gates and analog elements such as bipolar transistors. A mixed D‐A circuit simulator was developed which directly simulates the mixed D‐A circuit. The simulator combines closely the logic simulation and circuit analysis, and provides an accurate and efficient simulation of the mixed D‐A circuit. The management of the simulation time is different for the logic simulation and the circuit analysis. By simply combining those two techniques, it is difficult to provide an efficient simulation for the general mixed D‐A circuit containing a feedback loop.From such a viewpoint, a simulation method was developed in which the mixed D‐A circuit is decomposed into blocks along the direction of the signal propagation, and each block is simulated by time‐first processing. The block containing a mixed D‐A loop is decomposed hierarchically into blocks until the analog subcircuit is separated. By the proposed method of simulation, an efficient simulation is provided for the general mixed D‐A circuit containing a feedback loop by grouping the processing for the analog subcircuit. However, this is time‐consuming.
RSA security
Authors: Kurosawa Kaoru , Matsu Kazuo , Kasai Hirohumi 
Published: July 2007

AbstractRSA is a typical public key cryptosystem, but whether or not breaking RSA is as hard as prime factorization is unknown. It is known that if the LSB sequence obtained from iterated cipher texts of RSA is distinguished from the true random sequence in a polynomial time, it is possible to break RSA. Consequently, by testing the quality of this pseudorandom sequence, the security of RSA can be evaluated. It is known also for RSA that guessing the least‐significant bit of the original message from the encrypted message with probability 1/2 + 1/poly(n) is equivalent to finding the whole original message.In this paper, it is shown first that guessing the value of the original message by mod L with probability 1/L + 1/poly(n) is as difficult as finding the entire original message. Based on the result, a multivalued pseudorandom number generator is given. Those based on the hardness of the quadratic residue property also are shown. Statistical testing of those pseudorandom numbers is attempted, leading to the evaluation of the reliability of RSA.
A global router for standard cell VLSI with feed‐through assignment optimization
Authors: Sugai Yasuo , Hirata Hironori 
Published: July 2007

AbstractA global routing for a standard cell VLSI poses two important problems: how often we use it with feed‐through and where to install it beside the layout to trunk lines. To minimize the total number of tracks at the level of detailed routings, we avoid local congestions. Thus the layout touting with feed‐through becomes necessary which does not depend on the routing order. For an optimization problem for a large number of combinations of routings, Kirkpatrick et al. have proposed a simulated annealing method. This method is a stochastic sequential improvement method. Its features are an ability to escape from local solutions and the obtained solution depends on the initial conditions and routing order. In this paper we proposed a new method for a global routing for a three‐layer standard cell VLSI with feed‐through based on the simulated annealing method. Features of our method are an enhanced degree of freedom of routings, allowance for changes of directions of feed‐through and an effective acoidance of local congestions. Through experiments on a computer we achieved a drastic reduction of the number of tracks compared with that of the existing method.
Culation algorithms of primary functions on a digital signal processor
Authors: Ebina Tsuyoshi , Ishii Rokuya 
Published: July 2007

AbstractRecently, many kinds of digital signal processing systems are proposed. In realizing these systems on a digital signal processor (abbreviated as DSP), in most cases primary functions must be computed. When we compute primary functions on DSP, we make tables and use them for these function values for requirements. By using this method, we cannot obtain precise values and thus require a large memory region for tables. If we use DSP for complicated computations, application fields are limited.This paper presented calculation methods of a division, sin(X), cos(X), tan(X), an arctangent, a square root, a logarithm and an exponential function. Further, execution speeds and execution precision were obtained. We used the digital signal processor MSM6992 made by OKI Electronic Industry Co. On the DSP, the execution program step number is 24 to 77.The calculation error is less value than 2 to 4 times the value which corresponds to the least significant bit in a DSP with floating point arithmetic. Calculation of primary functions by the proposed methods does not require a large memory region (except for the calculation of a square root of an exponent). Then using proposed methods, we can implement a complex system using primary functions on a one‐chip DSP.
A study on biquad SCF with one operational amplifier
Authors: Komazaki Tomokazu , Gunji Katsuhiko 
Published: July 2007

AbstractProgress in decreasing the power consumption of communications equipment has created a need for corresponding decreases in the power consumption of switched capacitor filters (SCF). Ishikawa and Laker haver suggested reducing the number of opamps used by means of time sharing. In the present paper a general form of a biquad SCF with a single opamp for time‐sharing use is proposed and a new biquad SCF design is derived. The possibility of designing such SCF's with a small DC offset is demonstrated. Tests with individual components confirm the effectiveness of such devices.
A design of matching network for lumped complex load using hyperbolic‐class nonuniform transmission line
Authors: Endo Isao , Akiyama Michio , Nemoto Yoshiaki , Sato Risaburo 
Published: July 2007

AbstractThis paper presents a new method of matching network design for lumped complex loads using nonuniform transmission lines. An equivalent circuit of a squared trigonometric or squared hyperbolic nonuniform transmission line consists of a cascade connection of a lumped reactive element, a pseudo‐uniform transmission line, an ideal transformer, and a lumped reactive element. The lumped reactive elements in the equivalent circuit may possess positive or negative element values.Based on the notion of cancellation of the negative element of the equivalent circuit and the positive element of the load impedance, it is possible to design a broadband matching network for a lumped complex load.This paper discusses mainly the impedance matching for an RC series load. Numerical examples are given and an experimental result demonstrates the validity of the theory.
Saving viterbi decoder states for general rate 1/2, constraint length K, quick look‐in codes
Authors: Tajima Masato , Kobayashi Kenzo , Suzuki Hideo 
Published: July 2007

AbstractThis paper discusses how to reduce the number of states in the main decoder placed in an SST Viterbi decoder for general rate 1/2, constraint length K, and quick look‐in codes. Presented are three different cell configurations for which state elimination is possible if an MAP estimation method is applied for branch metric computation. It is shown that for each of these cell configurations, a considerable portion of decoder states can be eliminated without any accompanying performance degradation. It is clarified also that, by transforming encoder states to syndrome former states (i.e., dual states), these cell configurations can be mapped to those discussed in Schalkwijk's paper.
Linear structure and error performance analysis of block PSK modulation codes
Authors: Takata Toyoo , Fujiwara Toru , Kasami Tadao , Ujita Satoshi , Lin Shu 
Published: July 2007

AbstractThis paper investigates the linear structure and error performance analysis of block PSK modulation codes. The integer group (0, 1, 2, 2l – 1) under the modulo‐2l addition, denoted as Sl, is chosen to represent a 2‐dimensional 2l‐PSK signal set. A necessary and sufficient condition is derived for a block PSK code over Sl to be closed under the component‐wise modulo‐2l addition. Error performance of block PSK codes also are analyzed for an AWGN channel with soft‐decision maximum likelihood decoding. Upper bounds and simulation results on the error probabilities for some specific codes are shown.
A new method for discrete optimization problems
Authors: Nakagawa Yuji 
Published: July 2007

AbstractA generalized optimization system with a discrete decision space, is described, and on an optimization problem is defined which is associated with the system. A new solution method, which is called modular approach (MA), is presented to solve the optimization problem. This method extends the Morin‐Marsten hybrid idea to solve troublesome problems of dynamic programming. The present method is also an extension of the branch‐and‐bound method using breadth‐first search.
Multiobjective fuzzy linear regression analysis and its application
Authors: Sakawa Masatoshi , Yano Hitoshi 
Published: July 2007

AbstractThis paper tests three formulations of linear programming problems used to derive a fuzzy linear regression model, which are based on three different indices representing the necessity and of sufficiency equivalence relations between fuzzy numbers. It is shown that those formulations are extensions of three traditional formulations for fuzzy data. The trade‐off between “fit” (between the model and the observed data) and the “fuzziness” (of the model) is considered to be a multiobjective decisionmaking problem. This leads to the formulation of a multiobjective programming problem for deriving the fuzzy linear regression model. Corresponding to this situation, an interactive decision‐making procedure is proposed, which is applied to the problem of estimating the pork demand.
Complex chebyshev approximation for IIR digital filters with arbitrary log magnitude and phase functions
Authors: Kobayashi Takao , Imai Satoshi 
Published: July 2007

AbstractThis paper proposes a technique for designing IIR digital filters to have prescribed magnitude and phase responses. The technique is based on an iterative weighted least‐squares approach in the frequency domain.A weight updating procedure is introduced to minimize the complex logarithmic error in the Chebyshev sense. The real and imaginary parts of the complex logarithmic error represents the log magnitude and phase errors, respectively. Both the log magnitude and phase errors of the resulting filter become nearly equiripple. Filter coefficients at each iteration are computed efficiently using FFT and a fast recursive algorithm for a set of linear equations derived from the weighted least‐squares problem. Several design examples are shown to demonstrate the effectiveness of the proposed technique.
Identification of fuzzy parameters by interval regression models
Authors: Ishibuchi Hisao , Tanaka Hideo 
Published: July 2007

AbstractTanaka et al. formulated the problem of determining the linear regression expression with fuzzy parameters as a fuzzy regression analysis problem, using the data for the input‐output relation. This paper discusses such a fuzzy regression analysis, and proposes a method which identifies the fuzzy parameters using the interval regression expression.First, a method is proposed which identifies the fuzzy parameters with symmetrical triangular form from the interval regression expression. Then a method is proposed which identifies the fuzzy parameters with asymmetrical trapezoid form from two interval regression expressions. Using numerical examples, a method is illustrated which identifies the asymmetrical trapezoid fuzzy parameters from the usual point data and the fuzzy data.The method proposed herein employs the interval regression expression based on the interval operations, which leads to the merit that the procedure is simple and easy to understand compared with the conventional method employing the operations of fuzzy numbers. The fuzzy regression expression with asymmetrical trapezoid fuzzy parameters is a generalization of the fuzzy regression expression with symmetrical fuzzy parameters obtained by the conventional method.
New IIR‐adaptive algorithms based on orthogonalization method
Authors: Fukumi Minoru , Omatu Sigeru 
Published: July 2007

AbstractRecently, for signal processing such as echo cancellation and equalization it is required to develop IIR‐adaptive digital filters. This paper proposes a new‐type IIR‐adaptive algorithm based on the orthogonalization method, considers the convergence of the algorithm, and verifies its effectiveness by simulation. White's algorithm is one of IIR‐adaptive algorithms reported thus far and Feintuch's algorithm is known as its approximation algorithm. This paper also derives an IIR‐adaptive algorithm using both Feintuch's algorithm and the orthogonalization method.First, it can be shown that a generalized algorithm (IIR‐LI) of IIR‐learning identification method based on previous heuristic methods can be derived using the idea of Feintuch's algorithm and the conjugate gradient method. Next, a new IIR‐adaptive algorithm (IIR‐AACG) based on the orthogonalization principle of the conjugate gradient method is presented. Further, by applying the orthogonalization method to a past input vector sequence we derive an IIR‐Affine projection algorithm (IIR‐AP). Finally, these algorithms are compared by computer simulation to verify the effectiveness of the orthogonalization method.
Theory of extended interpolation approximation and upper and lower bounds of error
Authors: Kida Takuro , Yoshioka Leopoldo Hideki 
Published: July 2007

AbstractAssume that signal f(t) is impressed on N parallel time‐invariant linear networks Hm(w)(m=1∼N), and consider the uniformly sampled values gm(nT)(m = 1∼N; n = 0, ±1, ±2,; T <0) of the output signal gm(t)(m=l∼N). This paper discusses the following problem from a unified viewpoint. The response g(t), when the signal f(t) is passed through the given filter H(w), is to be approximated by an expression y(t) which is the sum of the forementioned sample values multiplied by time functions ψmn(l)(m = 1∼N; n= 0, ±1, ±2, ). It is assumed that the signal f(t) belongs to the set l of the signals for which the weighted square integral of the Fourier spectrum F(w) is not greater than a positive number A. In the foregoing, ψmn(t) is called the interpolation function.First, it is shown that given Hm(w)(m =1∼N), the time‐limited interpolation function, which minimizes the upper limit emax(t) of the error e(t) = [g{t)‐y(l)] over all f(t) belonging to F, is obtained by shifting the impulse responses ψ(l)(m=1∼N) of certain N linear time‐invariant interpolation filters ψ()w(m=1∼N) along the time axis. The analytic form for this function is given. Assuming that Hm(w) (m=1∼N and ψm(w)(m=1∼N) are optimized so that the measure emax(t) of the error is minimized, the upper and the lower bounds of the optimal emax(t) are shown. Considering an application where N is large, the optimization is discussed in the sense that the equivalent multiplicity is reduced at the sacrifice of the approximation error.
Ring code – code symmetry and uncorrectable errors
Authors: Noda Tadayoshi , Hata Masayasu 
Published: July 2007

AbstractThis paper proposes a ring code as a new burst error‐correcting code, where the check sequence forms a ring on a square code array. The code is a quasi‐cyclic quasi‐optimal code with a symmetrical structure. Because of its cyclic decoding process, it has a feature that the error‐correcting code for a long burst can easily be constructed.This paper discusses also the properties of the code, as well as the correspondence between the code symmetry and the uncorrectable property. The relation is described clearly from the viewpoints of geometrical structure and the group theory. The computation for the uncorrectable probability is established. Finally, the two‐dimensional ring code is considered, but the theory can be extended to the three‐dimensional and the higher‐dimensional ring code. Due to the symmetry of higher order, the hidden errors are reduced and the error‐correcting power is improved. The exact evaluation of the performance of the code, however, is left to another paper.
A method of designing FIR fan filters based on McClellan transformations
Authors: Tazawa Shiro , Honma Hitoshi , Sagawa Masahiko 
Published: July 2007

AbstractThis paper describes a method of designing the fan filter with a steep cutoff characteristic, using McClellan transformation. The conventional design by McClellan transformation has a problem in that the cutoff region of the fan filter is broad due to the restriction to a lower order of the subfilter employed.From such a viewpoint, this paper proposes a systematic design method for the subfilter with arbitrary order. First, it is pointed out that the ideal response of the subfilter can be represented in a functional form. Then the error function is defined in regard to the ideal response, and the design is shown for the subfilter where the filter coefficients minimize the error function. Finally, a design example is discussed, and it is shown that a fan filter with a steeper cutoff characteristic than in the conventional method can be designed by the proposed method.
A further result on the construction of asymptotically good convolutional codes for low rates
Authors: Nishijima Toshihisa , Ishii Hiroaki , Inazumi Hiroshige , Hirasawa Shigeichi 
Published: July 2007

AbstractJustesen presented the asymptotically good block codes, and then the asymptotically good convolutional codes Rj in a constructive way. The latter are the concatenated codes, where the outer code is the convolutional code generated by the generator polynomial of Reed‐Solomon code, and the inner code is Wozencraft's randomly shifted code. The performance of Justesen's convolutional code is not necessarily high for low code rates. Sugiyama, Kasahara, Hirasawa and Namekawa presented new asymptotically good convolutional codes Rc by applying the second order concatenation to Justesen's convolutional codes Rj, which gave an improvement for the low code rates.This paper presents constructively new asymptotically good convolutional codes R(J), by comgining the second‐order concatenation of the forementioned improved convolutional codes Rc and the generalized concatenated codes. It is shown that the new codes R(J) always have a higher performance than that of the convolutional codes Rc, and have the best performance for the low code rates 0<R<0.25., among the asymptotically good convolutional codes known up to now.
Active R filter realization and its trimming technique
Authors: Hayahara Etsuro , Hiranos Satoshi 
Published: July 2007

AbstractThis paper describes a design approach for constructing active R filters to simulate the doubly resistively terminated LC circuit and its compensation techniques. Using this approach, the necessary compensation resistance values can be obtained from only one measurement of the filter response.The approach in this paper is applied to an all‐pole lowpass filter. However, it is shown that it can also be applied to a low‐pass filter having transmission zeroes.