High-frequency comparison of gic-simulated inductance circuits

It is shown that there is a significant difference in the high-frequency behaviour of two well-known generalized immittance converter realizations of simulated inductance. One of the realizations yields a Q factor that is highly sensitive to mismatch of amplifier bandwidths whereas the alternative realization can be designed to give a Q factor that is highly insensitive to this mismatch.     

A modified sensitivity measure for linear digital systems

In this paper a new sensitivity measure for state space systems is proposed. This new measure is a modified form of Tavsanoglu and Thiele's measure but has three advantages: (1) it is more precise than Tavsanoglu and Thiele's measure when the parameters of the state space realizations contain 0 and ±1; (2) it can be used to explain why the sparse Schur and Hessenberg realizations can give better actual sensitivity performance than the corresponding fully parametrized optimal realizations; (3) it is identical with the global round-off noise gain G = tr(QW) + y obtained by Hwang under a dynamic constraint.     

Transfer matrix realization using RC:GIC Networks

A general synthesis procedure for realizing any stable voltage transfer matrix using current-conversion type generalized impedance converter (GIC)s is outlined. Each row of the transfer matrix is realized separately as an M-input, single-output grounded RC:GIC network where M is the number of columns in the transfer matrix. The realization procedure is illustrated by an example. Using this approach, a second-order filter has been obtained capable of realizing simultaneously highpass, band-pass and low-pass transfer functions and using fewer passive components and operational amplifiers than the popular state-variable realizations. The various sensitivities of the second-order realizations are low and comparable to the state-variable realizations. A similar method can be developed for current transfer matrix invoking duality and thus using the voltage-conversion type GICs.     

Structure generation and performance comparison of elliptic Gm‐C filters

Starting from a set of matrices describing a general G_m‐C filter topology, a procedure is developed for generating structures of lowpass filters. As the matrices and the filter topologies have a one‐to‐one correspondence, an algebraic method is used to identify filter topologies with desired properties, here, transfer functions with finite jω‐axis transmission zeros, specifically elliptic filters. Sensitivity expressions for these structures are derived and a performance comparison based on a set of chosen criteria is made. For a specified elliptic transfer function, filters with only grounded capacitors and those containing also floating capacitors emerge as alternative realizations, as are filters with a single input and those with distributed inputs. For third‐order functions, a detailed comparison is performed of leapfrog (LF) and inverse follow‐the‐leader‐feedback (IFLF), the most popular special cases, and of topologies that have also floating capacitors (LF_f, IFLF_f), as well as of a novel configuration that uses also distributed inputs (DI_f) and leads to a reduced element count. Design guidelines and restrictions are given, which follow from the derived results with focus on the circuits' sensitivity performance and other properties important for IC implementation. Copyright © 2004 John Wiley & Sons, Ltd.     

A class of non-canonic,driving-point immittance realizations of passive,common-ground,transformerless, two-element-kind RLC networks

A new class of non-canonic, driving-point immittance realizations of passive, common-ground, transformerless, two-element-kind RLC networks with minimum number of nodes is presented. Six new algorithms of realization are developed by application of canonic, orthogonal matrix transformations with reduced number of degrees of freedom. the number of applied RLC elements of one kind can be minimized and of the other kind reduced, while their parameter values are calculated directly in a linear way.     

Partial fraction expansion–based realizations of fractional-order differentiators and integrators using active filters

Approximations of the fractional-order differentiator and integrator operators s^±r are proposed in this work. These approximations target the realization of these operators using standard active filter transfer functions. Hence, circuit implementations in integrated circuit form or in discrete component form are significantly facilitated. Complementary metal-oxide-semiconductor (CMOS) realizations of the proposed approximations are given and validated via simulations using the AMS 0.35 μm CMOS technology, while experimental results using operational amplifier circuits are tested and confirm the proposed theory.     

Sensitivity of third- and higher-order filters

For any realization of a network function F(s) = N(s)/D(s), the sensitivities that can be most readily calculated are those of the coefficients in N(s) and D(s). A simple relationship is derived that enables one to calculate the root (pole and zero) sensitivities of F(s) in terms of the coefficient sensitivities. The root sensitivities, in turn, enable one to calculate the root pair Q and root frequency sensitivities, which can be used to characterize and compare different realizations of F(s). Application to 3rd- and 4th-order filters reveals formulations that are more elegant than those already known in the literature.     

I−V relations in semiconductors with ionic motion

Semiconductors with mobile donors and acceptors are mixed-ionic-electronic-conductors, MIECs, which exhibit peculiar electronic (electron/hole), I _e , current-voltage relations. This is a result of the redistribution of the ions under the applied electrical potential. MIECs are usually ionic materials which exhibit relative low electron/hole mobilities as compared to the materials used in the semiconductor industry. However, thin layers of MIECs exhibit a low resistance and fast response and become of increasing interest. The I _e −V relations are discussed for a few typical examples. It is shown that they depend on the energy band gap as when it is large, the semiconductor is either p-type or n-type. The I _e −V relations depend also on the nature of the electrodes, whether blocking for ion exchange or not. Experimental results for Cu₂O are presented and analyzed using one of the models discussed. ICE-2005, KIST, Seoul, Korea, (Invited)     

Full flexible performance characterization of a feedback applied transistor with LNA applications

In this paper, the full flexible performance characterization of a transistor with series inductive/parallel capacitive feedback is carried out in terms of LNA applications. For this purpose, the input VSWR V_in–maximum available gain G_Tmax variations are constructed for a high technology low-noise transistor that is subject to the required noise figure F_req(f) ≥ F_min(f) along the device's operation band depending on the feedback. These V_in–G_Tmax variations result in the application of a design chart that indicates which value of feedback can be applied within which region of the operation band with the improvable trade-off between the V_in and output VSWR V_out for the Freq(f) ≥ Fmin(f). Following this, the optimum trade-off between V_in and V_out is made for the necessary operation frequency regions using the load impedance Z_L as an instrument with the predetermined source impedance Z_S. Finally, the LNA applications of a series inductive/parallel capacitive feedback applied transistor with the optimum V_in, V_out, and G_T subject to Freq(f) ≥ Fmin(f) ≥ are also presented as distributed across the entire bandwidth in the different operation bands. It can be concluded that this rigorous work will enable a designer to utilize the entire operation frequency band of transistor through using only a single series inductive/parallel capacitive feedback for the LNA designs of Freq(f) ≥ Fmin(f) with the optimum trade-offs among its performance measures.     

Electronically tunable low-component-count current-mode biquadratic filter using dual-output current followers

In this paper, a realization of a current-controlled three-input single-output current-mode universal biquadratic filter using dual-output current followers (DO-CFs) as active components is described. Based on the use of the current-controlled conveyor working as the DO-CF, the proposed circuit employs only two DO-CFs and two grounded capacitors that provide the advantage of an electronic tuning capability and is of special interest from the IC fabrication point of view. By suitably selecting three input signals, the filter can realize all of the standard biquadratic filtering functions, i.e., lowpass, bandpass, highpass, bandstop and allpass, all at a high impedance output which enables easy cascading in the current-mode operation. The natural angular frequency (ω _o ) and the bandwidth (BW) of the proposed circuit can be tuned independently and electronically over a wide range by adjusting the external bias currents. In addition, no critical component matching conditions are required for all the filter response realizations, and both active and passive sensitivities are low. PSPICE simulation results are used to confirm the characteristics of the proposed circuit.     

An optimal algorithm for rectilinear steiner trees for channels with obstacles

The channel rectilinear Steiner tree problem is to construct an optimal rectilinear Steiner tree interconnecting n terminals on the upper shore and the lower shore of a channel without crossing any obstacles inside the channel. However, intersecting boundaries of obstacles is allowed. We present an algorithm that computes an optimal channel rectilinear Steiner tree in O(F₁(k)n + F₂(k)) time, where k is the number of obstacles inside the channel and F₁ and F₂ are exponential functions of k. For any constant k the proposed algorithm runs in O(n) time.     

The variable-speed reluctance machine with cageless barrier rotor

Contents The frequency converter supply of rotating-field machines stimulates an interest in machine variants where induced rotor currents are avoided and only imposed rotor currents are permitted.The cageless reluctance machine with barrier rotor is such a variant and its prospects as a substitute for the converter-supplied cage induction motor are investigated.

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Die Reluktanzmaschine mit käfiglosem segmentiertem Rotor

Übersicht Bei Umrichterspeisung von Drehfeldmaschinen besteht Interesse an solchen Maschinenvarianten, die keine induzierten Rotorströme aufweisen und bei denen nur eingeprägte Rotorströme vorkommen können. Die käfiglose Reluktanzmaschine mit segmentiertem Rotor ist eine solche Variante, deren Aussichten als Ersatz für den Käfigläufer-Induktionsmotor bei Umrichterspeisung untersucht werden.

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List of symbols I _d d-axis current component of reluctance machine - L _q q-axis current component of reluctance machine - I _a active current component - I _r reactive current component - N _p number of pole pairs - R ₁ primary resistance - R _2' secondary resistance (referred to the primary) - U(U') primary voltage (behind primary resistance) - (X _d )X _d (per-unit)d-axis reactance of reluctance machine - (X _q )X _q (per-unit)q-axis reactance of reluctance machine - X _o induction machine reactance at zero slip - X induction machine reactance at infinite slip - X _m /X p.u. magnetizing/leakage reactance of induction machine - Z _d /Z _q d/q-axis impedance - d _r rotor diameter - g airgap length - s slip of induction machine - slip-dependent angle of induction machine - load angle of reluctance machine - _p pole pitch     

Crystal band-stop filters with improved spurious resonance behaviour

It is a well known fact that piezoelectric band-stop filters manifest not only the desired stopband at the fundamental resonant frequency of the crystal, but also additional stopbands at its spurious resonant frequencies. The greater the degree to which such parasitic attenuation peaks are to be suppressed, the more complex is the required circuitry. The most common crystal band-stop filter circuits can be considered as all-pass sections in which a capacitance is ‘disturbed’ over a narrow bandwidth by a resonant circuit. If this ‘disturbance’, possibly after conversion by means of known one-port equivalents, consists of a high impedance series resonant circuit with the inductance L_s in parallel to the entire lattice arm R/jx₁, the 3 dB bandwidth of the stopband becomes Δω₀= R/L_s(1+x) in the loss-free case. Sometimes the dual representation of the ‘disturbance’ is more appropriate. With a finite crystal Q-factor of Q_q, the insertion loss of a desired or parasitic stopband assumes the finite maximum value ǎ ～ In (1+Q_qΔω0/ω_∞). The width and height of the possible attenuation peaks are given in formulas, normalized curves and worked examples for seven band-stop filter circuits of increasing complexity, each with a single crystal.     

Wide‐band aperture array using a four‐channel manifold‐type planar multiplexer and digital 2‐D IIR filterbank

Emerging wide‐band communications and spectrum‐sensing systems demand support for multiple electronically scanned beams while maintaining a frequency independent, constant far‐field beam width. Realizing existing phased‐array technology on a digital scale is computationally intensive. Moreover, digitizing wide‐band signals at Nyquist rate requires complex high‐speed analog‐to‐digital converters (ADCs), which is challenging for real developments driven by the current ADC technology. A low‐complexity alternative proposed in this paper is the use of radio‐frequency (RF) channelizers for spectrum division followed by sub‐sampling of the RF sub‐bands, which results in extensive reduction of the necessary ADC operative frequency. The RF‐channelized array signals are directionally filtered using 2‐D digital filterbanks. This mixed‐domain RF/digital aperture array allows sub‐sampling, without utilizing multi‐rate 2‐D systolic arrays, which are difficult to realize in practice. Simulated examples showing 14–19 dB of rejection of wide‐band interference and noise for a processed bandwidth of 1.6 GHz are demonstrated. The sampling rate is 400 MHz. The proposed VLSI hardware uses a single‐phase clock signal of 400 MHz. Prototype hardware realizations and measurement using 65‐nm Xilinx field‐programmable gate arrays, as well as Cadence RTL synthesis results including gate counts, area‐time complexity, and dynamic power consumption for a 45‐nm CMOS circuit operating at B _DC = 1.1 V, are presented. Copyright © 2016 John Wiley & Sons, Ltd.     

A unified filter for singular Markovian jump systems with mixed delays based on an extended free-matrix-based inequality approach

In this article, the problem of unified filters design including H_∞ , L₂ − L_∞ , passive, dissipative filters and their reduced-order ones is addressed for continuous-time singular Markovian jump systems with discrete and distributed delays. Unlike some existing works, the mixed delays can be fully captured by proposing an extended free-matrix-based integral inequality. By considering two cases of distributed delays, two novel criteria are presented to ensure the filtering error system to be stochastically admissible and extended dissipative. Some numerical examples are provided to illustrate the effectiveness of the unified filter design methods.     

Crack formation in MLCCs depending on position with and without post-heat treatment

The crack formation behavior and mechanical properties, hardness (H), modulus (E), and fracture toughness (K _IC), at each plane of BaTiO₃ based multilayer ceramic capacitors (MLCCs) have been investigated and estimated using a nanoindentation technique, including effects of the post-heat treatment and the external electrode on the crack formation and mechanical properties. The crack length in each plane, length (x plane) and width (y plane) planes, has been measured for MLCCs with and without the post-heat treatment, as a function of the distance from the internal electrode. H and E values are 11.5–12.0 GPa and 175–190 GPa, respectively, independent of the plane and the post-heat treatment. The crack length in the x plane is smaller than that in the y plane, which is gradually increased as the indentation position is far away from the internal electrode. The external electrode affects the crack formation in regions near to the internal electrode, showing small crack length till 20 μm from the internal electrode. K _IC values in the x plane are larger than those in the y plane. The external electrode affects only the K _IC values in the x plane within the error range, without effect of the post-heat treatment.     

Digital filter design with state space method for 1‐bit signal processing based on delta‐sigma modulation

One‐bit signal processing based on delta‐sigma modulation has been studied for hardware implementation of signal processing systems. In the 1‐bit signal processing, finite word‐length problems such as overflow and coefficient quantization error occur. To solve the problems, a new design method with state space is proposed in this paper. Digital filters are designed to show the feasibility of the method. First, the L₁/L₂‐sensitivity is shown to evaluate coefficient quantization error and L₂ scaling constraints to prevent overflow. Second, a state space equation is presented and the L₁/L₂‐sensitivity and L₂‐scaling constraints are extended to take the filter structure and oversampling effects into account. Finally, the proposed method is shown to attain a higher SNR than conventional ones. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(4): 48–56, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21075     

On the perturbation analysis of the limit cycle in oscillators with shifting bias

We propose a method of perturbation analysis of nearly sinusoidal oscillators with shifting bias, obtained by generalizing a method recently discussed in the literature [1] (Buonomo A, Di Bello C. IEEE Transactions on Circuits and Systems, 1996; CAS‐43: 953–963). The problem of periodic oscillations is formulated as a regular perturbation problem, P_ϵ(x) =0, whose peculiarity is that the limiting linear problem, P₀(x)=0, obtained when the perturbation parameter ϵ tends to zero, has a non‐purely harmonic solution x₀=B₀+A₀ cos ϑ. We give a simple condition for the existence of a periodic oscillation and an analytical method for constructing it in the form of a power series in ϵ. Unlike the existing perturbation methods, the method here proposed, which remains in the spirit of the bifurcation process of Poincaré, allows us to obtain the coefficients of the series solution, to an order in ϵ as great as we want, using recurrence formulae. The results of the analysis of a typical LC oscillator are given to show that these formulae are very useful as a practical method for determining all of the characteristics of the periodic oscillation, such as the harmonic content and the frequency correction due to the non‐linear effect. Copyright © 2000 John Wiley & Sons, Ltd.     

Robust fault estimation for Takagi-Sugeno fuzzy systems with state time-varying delay

This paper deals with the problem of H_∞ robust fault estimation for a class of Takagi-Sugeno (T-S) fuzzy systems with state time-varying delay, sensor, and actuator faults. The faults considered in this paper are time-varying signals whose k-order derivatives with respect to time are bounded. Then, we propose a proportional multiple integral observer to achieve simultaneous estimation of system states and time-varying actuator and sensor faults. Furthermore, one less conservative delay-dependent sufficient condition for the existence of fault estimation observer is given in terms of linear matrix inequality. The disturbance attenuation is constrained to a given level using H_∞ performance index. Finally, simulation results of one numerical example is presented to show the effectiveness of the proposed method.