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This paper presents a high step-up converter, which utilizes a three-winding coupled inductor and a rectified voltage-doubler circuit to obtain high step-up gain for fuel cells. The proposed converter functions as an active-clamp circuit, which relieves large voltage spikes across the power switches. Thus, power switches with low-voltage-rated can be utilized to reduce conduction losses and circuit cost. Energy stored in leakage inductances of the coupled inductor is recycled to the output terminal, resulting in efficiency improvements. In addition, the coupled inductor in the presented converter can also have extra windings in order to achieve higher voltage gain. Finally, a prototype circuit with an input voltage of 60V and an output voltage of 380V is developed for a 1000W-rated fuel cell power-generation system to validate its performance, and experimental waveforms and measured efficiency under different input voltages and output power level are demonstrated. Copyright © 2016 John Wiley & Sons, Ltd.

This paper proposes an accurate tunable-gain 1/x circuit. The output voltage of the 1/x circuit is generated by using a capacitor-charging time that is inversely proportional to the input voltage. The output voltage is independent of the process parameters because the output voltage depends on the ratios of the capacitors, resistors, and current mirrors. The voltage gain of the 1/x circuit is tuned by an 10-bit digital code. The 1/x circuit was fabricated using a 0.1 8μm CMOS process . Its core area is 0.011m m 2 (144μm×78μm) and it consumes 278μW at VDD=1.8V and fCLK=1MHz. Its error is within 1. 7% at VIN=0.05~1V.

This chapter contains sections titled: Frequency Response of a Transfer Function Frequency Response and Impedance of Simple Circuits Frequency Response for Ladder Networks Generalized Technique for Determining Frequency Response Problems

This article presents an unequal Gysel power divider (UGPD) based on circuit transformation, which is converted from a Π- to a T-type circuit. The Π-type circuit of a conventional unequal Gysel divider consists of two different value resistors and its connection transmission line. In the proposed T-type circuit, the dummy transmission line and the other transmission line with shunt resistor at center position is connected in parallel. Theoretical analysis was performed to derive the design equations for the proposed circuit conversion. For the validation of the circuit transformation, the UGPD using a T-type circuit at the center frequency of 2 GHz was fabricated and measured. The measured characteristics agreed well with the simulation results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1529–1531, 2015

The impulse spark-over voltage of the gas discharge tube (GDT) is strongly related to the rate of rise (RoR) of the voltage. At present, due to the convenience of the test instrument, conventional impulse waveforms, such as 1.2/50 and 10/700 μs, are often adopted to conduct such kind of test for GDT. It has been found that these waveforms are able to generate valid waveforms only with limited RoRs and relatively narrow valid voltage ranges. This paper deals with a simple series RC circuit to test the GDT's impulse spark-over voltage using a ramp voltage, which is approached by an initial portion of a steeply rising voltage impulse whose normal peak value is several times the breakdown voltage of the GDT. The basic circuit theory is described, and the RoR of the output voltage is correlated with the circuit parameters. Moreover, the series RC circuit in this paper is found to be able to deliver a ramp voltage with more consistent RoR than an RLC circuit. The results in this paper provide some suggestions for the revision of relevant standards (e.g., ITU-T K.12 and IEC 61643-311). Circuit parameters for different RoRs ranging from 100 V/μs to 1 kV/ns are also established. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In this paper we explore the Vs-optimality criterion that was proposed in Ginsburg and Ben-Gal (IIE Trans. 2006; 38:445–461) as a new design-of-experiment (DOE) alphabetic optimality criterion. The Vs-optimality criterion seeks to minimize the variance of the optimal solution of an empirically fitted model. We show that the Vs-optimality citerion is well related to known alphabetic DOE criteria. However, it focuses on an 'optimization-seeking' experimental approach rather than an 'information-seeking' approach, which is often adopted by traditional optimality criteria. We illustrate the differences between these two approaches by a detailed example of a robust design of an RL-circuit. Copyright © 2009 John Wiley & Sons, Ltd.

This paper proposes an approach for a noise generator based on the chaotic circuit. In the proposed circuit, the diode is assumed to be an ideal switch. By means of this simplification, it is possible heuristically to understand the generation of several oscillation frequencies in the circuit. Also, it is possible to confirm the switching of the frequency from the attractor. The frequency depends strongly on the memory device in the circuit. More frequencies are generated by increasing the dimensions of the circuit since the spectral characteristics can be controlled easily by the variation of the circuit elements and by the increase of the dimensions of the circuit. Hence, the structure suggests an application to a noise generator. Further, the validity of the analysis results are confirmed by the circuit experiment.

This paper discusses the convolution integral of the circuit variable and the transfer function in the steady state of a circuit. It is shown that the integral can easily be calculated by the Shooting method when the transfer function to be calculated has a simple form. Using the proposed method of calculation, the steady-state operation is analyzed for the periodic switching circuit which is controlled by the closed loop, such as the switching converter. A method is proposed that precisely determines the steady-state operation of the overall circuit, while precisely analyzing the steady-state operation of the loop circuit. The proposed method differs from the conventional method in that the circuit, including the loop circuit not analyzed but the loop-control circuit is represented by a transfer function separately from the overall circuit and the steady-state response is determined by the convolu-tional integral. Consequently, for closed-loop switching circuits of various structures, the operation can be determined precisely without enlarging the circuit scale to be analyzed. Another point compared to the past method is that the operation specifications for the circuit can be handled with a better transparency.

In this circuit transformation, the short-circuit transfer function of the resulting circuit is then exactly the same as the open-circuit voltage transfer function of the original circuit

Strip-line circuits at relatively higher frequencies can be considered as two-dimensionally extended circuits rather than one-dimensional transmission-line circuits. Hence, the stripline circuit can be modeled as a parallel-plate planar circuit. In this article, the following topics are reviewed and described based on the results of many researchers: (1) how to model the strip-line circuit to a parallel-plate waveguide circuit, which leads to a parallel-plate planar circuit; (2) how to analyze the strip-line modeled parallel-plate waveguide circuit based on planar circuit equations and conventional circuit theory where mode voltage and mode current are properly defined—especially how to construct the circuit equations after dividing the planar circuit into parallel-plate waveguides and planar junctions, and giving the corresponding the mode characteristic impedance and mode impedance; and (3) the practical analysis of a stub-type lowpass filter and branch-line 3-dB hybrid with the corresponding experimental results. The good agreement between the calculated and measured results demonstrates the validity of the present method of analysis. © 1993 John Wiley & Sons, Inc.

The feasibility is examined of using the Miller phase-compensation circuit to ensure the stability of the voltage limiter circuit in high-density CMOS DRAMs. First, analytical expressions are obtained for the condition of stabilization to support the comprehensive circuit design and it is shown that both load capacity and load current affect the stability significantly. Second, by using the analytical expressions, parameters for the voltage limiter and the phase compensation circuit are calculated. By computer simulation and experiment voltage variations within the chip are evaluated when the internal circuit operates and external power supply voltage is changed. Results show that the voltage variation caused by the operation of the internal circuit is within 10 percent, resulting in no problem in practice. The voltage variation caused by the change in the external power supply voltage is 3 percent in the case of low-frequency noise (tr, tf = 1μs) and is as large as 20 percent in the case of high-frequency noise (tr, tf = 10 ns) and attention must be paid to the latter case in the circuit design.

Voltage followers are used for the switched capacitor (SC) circuit simulating the ungrounded inductance based on the bilinear s-Z transform. The operation is confirmed by experiments. In the circuit configuration, it is pointed out that the block diagram often used in the derivation of the SC inductor complicates the circuit and the control clock and a new block diagram is proposed. The circuit derived by this method is simple since the control clock has two phases and the spreading of the capacitance value is only 2. Further, the circuit is not affected by the parasitic capacitance caused by the substrate-side electrode of the integrated capacitor which typically affects the characteristics significantly. Although two voltage followers are needed for realization of one inductor, it can be considered that effectively one inductor is constructed with one voltage follower if the adjacent SC resistance and SC inductor are shared with a voltage follower. It is described that the spread of the capacitance value in the entire filter can be made smaller than other SC inductors when this SC inductor is used in the SC filter. Simplification of the circuit with this filter is investigated.

The high-frequency performance of switched-capacitor filters is bounded mainly by the finite gain bandwidth product of operational amplifiers. In this paper, the effects of finite gain bandwidth product of operational amplifiers on the performance of FIR (transversal) filters using such amplifiers as delay elements (canonical circuit) is analyzed. Next, a new low-power consumption FIR switched-capacitor circuit for high frequencies, which we call a parallel cyclic-type circuit (PCTC), is proposed. The proposed circuit does not use operational amplifiers as delay elements. Instead, switches and capacitors are used for both the delaying and the weighting operations. We present a basic circuit using subblocks, a circuit with reduced number of capacitors, and a modified circuit having plural operational amplifiers for higher-frequency use. We then show the design of a fourthorder FIR filter employing PCTC. Under the condition that sampling frequency is one-half of unity gain frequency of operational amplifier, computer simulations of fourth-order transversal switched-capacitor filters with canonical circuit and that with parallel cyclic-type circuit are performed and the experimental results of these circuits using discrete components are also given. Both demonstrate that the parallel cyclic-type circuit has significantly better performance than the canonical circuit.

This paper proposed a new type of constrained circuit containing a complete saturation-type nonlinear negative inductor and analyzes bifurcation phenomena and chaos generated in this circuit. The objective circuit is a three-dimensional autonomous one and it is governed by the circuit equation which is similar to the constrained equation of the ideal diode type proposed by the present authors. Because this circuit equation is described piece-wise by a two-dimensional equation, a Poincare map can be derived rigorously as a one-dimensional map. By means of this map, the process of the generation of logistic map chaos can be explained in detail. Moreover, the analyzing results are verified by circuit experiments.

With the recent development of integrated circuit technology, high-density and high-speed integrated circuits are produced. Then the wiring capacitance and wiring resistance of the circuit cannot be ignored, and it is necessary to develop a new circuit simulation method considering the parasitic effects of the wiring. The parasitic effect is represented by a distributed-constant circuit, and a partial differential equation representing the distributed-constant circuit must be solved to analyze the parasitic effects. When a partial differential equation is discretized by applying the finite-element method, however, the analysis of the circuit is reduced to the analysis of the higher-order equation which requires a tremendous computation time and memory capacity. This paper attempts to avoid this problem, and presents a method in which the circuit is analyzed equivalently without increasing the number of unknowns by applying the sequential analysis to replace the distributed-constant circuit by three resistors and two current sources.

Many second-order active filters with operational amplifiers have been proposed. Modeling the operational amplifier with nullators and norators, or else with an equivalent circuit with controlled sources, the transfer function is determined and matched with the desired filter function. In this paper, a new equivalent circuit is given for these filters. This is done by selecting three terminals in the circuit—the input and output terminals, together with another arbitrary terminal within the circuit—yielding a structure formed by a fundamental inverse-L circuit and a controlled source. the voltage transfer function is then given as the product of the inverse-L voltage ratio and the amplifier gain. Using this equivalent circuit, any filter may be represented by an inverse-L structure with any of the following two sets of elements: (1) inductance or FDNR, or (2) negative RC elements. Since the operation of the inverse-L filter can be analyzed easily merely by comparison with the operation of LC filters, the properties and operation of the active RC filters can be explained.

In the usual switched-capacitor filter (SCF), all the switches connected to a node are simultaneously on or off. Thus, every node voltage in the SC circuit changes in synchronization only to in-phase or out-phase clock, and has a very simple representation by RC equivalent circuit. This paper derives first the RC equivalent circuits for the basic SC circuits, and presents a method of simulation for active or passive RC circuit using an SC circuit, based on the obtained result. Finally, it is verified by several experiments that the SC circuit constructed by the proposed method operates as the theory predicts.

The research and development of a 4-valued integrated circuit, which is compatible to a binary circuit, is now being conducted intensively, aiming at the transfer of the merits of a multivalued system to a digital system. Another merit of the multivalued circuit is that the number of wirings and the wiring length can be reduced, which is useful in reducing the delay of driving due to the interwiring capacitance. On the other hand, the noise margin is a problem in the use of the multivalued circuit. From such a viewpoint, the authors are trying to improve the noise margin, and reported on the threshold control for the multivalued multithreshold circuit. In this circuit, however, the voltage step is reduced in correspondence to the control of the noise margin. This necessitates an increase of the supply voltage. As a result, when the binary ECL device is used as the circuit element, the number of levels that can be discriminated in the integrated circuit is restricted to 3 (two thresholds). This paper aims at the realization of up to a 5-valued 12-threshold control circuit by the binary device. For this purpose, a new threshold detector, the fundamental circuit which is obtained as an extension of that circuit, and the complementary circuit, are employed. In the threshold-setting circuit in the threshold detector, the control value and the voltage step can be set independently, which leads to the low-voltage supply. By introducing the signal distributor into the threshold detector, the maximum fan-in and fan-out, as well as the maximum number of thresholds are improved drastically. As an application, the threshold control 4-valued decoder was constructed experimentally, and it is shown that the noise margin is improved by 1.95 times or more.

This paper presents a synthesis method for the LC simulation-type active RC filter. In the proposed method, the second-order active RC filter, which has been used as the unit section in the traditional cascade structure, is modified into a multifeedback structure. The node equation of the original LC filter is set up and then simulated using the multi-input circuit for each node voltage, which is a modification of the second-order active RC circuit. The desired circuit is then obtained. As the original second-order active RC circuit, Sallen-Key's network and the SAB circuit of Friend are used in this paper. The design method for the circuit is summarized in a table as the design formula. The low element-sensitivity property of the resistor-terminated LC filter is retained in the proposed circuit. In particular, the element sensitivity is low when the relative errors among R- and C-elements are small as in the thin-film hybrid circuit. Finally, a design example and experimental result are shown for the fifth-order elliptic filter, verifying that the circuit operates in accordance with the theory.

Triplate-line circuit and strip-line circuit are the circuit structures used frequently at microwave and millimetric wave frequency bands. In these frequency bands, the strip-line width is not negligible compared with the wavelength. Also, the presence of electromagnetic field disturbance at junction and the mutual interaction of the frequency bands has strong effects on frequency characteristics. In this paper, to treat this kind of problem, the strip transmission line circuit is modeled and it is shown that the electromagnetic field distribution in this model is determined by the planar circuit equations. In solving these planar circuit equations, the circuit is separated into transmission line and junction circuit, and the mode impedance for each circuit is derived. It is shown that the input/output characteristics of the strip-line circuit are obtained by making analogous circuit equations conventional equations and solving them. This method of analysis is applied to a simple triplateline circuit and its wideband frequency characteristic is calculated for dc 18 GHz. Furthermore, the corresponding circuit is constructed and its frequency characteristic is measured for 4 ± 18 GHz. Since the calculated results based on this method of analysis agrees well with the measured results, the validity of this method of analysis is confirmed.