This paper describes the equivalent-circuit model of a metamaterial composed of conducting spheres and wires. This model involves electromagnetic coupling between the conductors, with retardation. The lumped-parameter equivalent circuit, which imports retardation to the electromagnetic coupling, is developed in this paper from Maxwell's equation. Using the equivalent-circuit model, we clarify the relationship between the retardation and radiation loss; we theoretically demonstrate that the electromagnetic retardation in the near-field represents the radiation loss of the meta-atom in the far-field. Furthermore, this paper focuses on the retarded electromagnetic coupling between two meta-atoms; we estimate the changes in the resonant frequencies and the losses due to the distance between the two coupled meta-atoms. It is established that the dependence characteristics are significantly affected by electromagnetic retardation.

The impedance expansion method (IEM), which was previously proposed by the authors, is a circuit-modeling technique for electrically-very-small devices. The equivalent circuits derived by the IEM include dependent voltage sources proportional to the powers of the frequency. However, the previous report did not describe how circuit simulators could realize such dependent voltage sources. This paper shows how this can be achieved by approximating the equivalent circuit using only passive elements.

This paper proposes a circuit modeling technique for electrically-very-small devices, e.g. electrodes for intrabody communications, coils for wireless power transfer systems, high-frequency transformers, etc. The proposed technique is based on the method of moments and can be regarded as an improved version of the partial element equivalent circuit method.

As devices continue to shrink, the parameter shift due to process variation and aging effects has an increasing impact on the circuit yield and reliability. However, predicting how long a circuit can maintain its design yield above the design specification is difficult because the design yield changes during the aging process. Moreover, performing Monte Carlo (MC) simulation iteratively during aging analysis is infeasible. Therefore, most existing approaches ignore the continuity during simulations to obtain high speed, which may result in accumulation of extrapolation errors with time. In this paper, an incremental simulation technique is proposed for lifetime yield analysis to improve the simulation speed while maintaining the analysis accuracy. Because aging is often a gradual process, the proposed incremental technique is effective for reducing the simulation time. For yield analysis with degraded performance, this incremental technique also reduces the simulation time because each sample is the same circuit with small parameter changes in the MC analysis. When the proposed dynamic aging sampling technique is employed, 50× speedup can be obtained with almost no decline accuracy, which considerably improves the efficiency of lifetime yield analysis.

A fast calculation tool for state-dependent capacitance of power distribution network is proposed. The proposed method achieves linear time-complexity, which can be more than four orders magnitude faster than a conventional SPICE-based capacitance calculation. Large circuits that have been unanalyzable with the conventional method become analyzable for more comprehensive exploration of capacitance variation. The capacitance obtained with the proposed method agrees SPICE-based method completely (up to 5 digits), and time-linearity is confirmed through numerical experiments on various circuits. The maximum and minimum capacitances are also calculated using average and variance estimation. Calculation times are linear time-complexity, too. The proposed tool facilitates to build an accurate macro model of an LSI.

An improved nonlinear circuit model for a GaAs Gunn diode in an oscillator is proposed based on the physical mechanism of the diode. This model interprets the nonlinear harmonic character on the Gunn diode. Its equivalent nonlinear circuit of which can assist in the design of the Gunn oscillator and help in the analysis of the fundamental and harmonic characteristics of the GaAs Gunn diode. The simulation prediction and the experiment of the Gunn oscillator show the feasibility of the nonlinear circuit model for the GaAs Gunn oscillator.

In this paper, active frequency selective surfaces (FSS) having a squared aperture with a metal plate loading are described. Active FSS elements using switched PIN diodes are discussed with an equivalent circuit model. A unit cell consists of a square aperture element with metal island loading and one PIN diode placed at the upper gap, considering the vertical polarization. The electromagnetic properties of the active FSS structure are changed by applying dc bias to the substrate, and they can be estimated by the equivalent circuit model of the FSS structure and PIN diode. This active FSS design enables transmission to be switched on or off at 2.3 GHz, providing high transmission when the diodes are in an off state and high isolation when the diodes are on. The equivalent circuit model in the structure is investigated by analyzing transmission and reflection spectra. Measurements on active FSS are compared with numerical calculations. The experimentally observed frequency responses are also scrutinized.

A compact circuit model for five-port on-chip transformer balun is presented. Compared to the conventional model, the proposed model is simpler without any accuracy degradation and ensures faster convergence time, which in turn enables flexible RF circuit design optimization. The validity of the proposed model is confirmed through extensive EM simulations and measurements.

In this research, the practical OTA-based inductors of all structures have been studied and their complete passive equivalent circuit models, where the effects of both parasitic elements and finite opened-loop bandwidth have been taken into account, also contain only the conventional standard linear elements i.e. the ordinary resistor, inductor and capacitor, without any infeasible high order element e.g. super inductor etc., have been proposed. The resulting models have been found to be excellently accurate, excellently straight forward, far superior to the previously proposed ones and completely realizable by the passive elements. Hence, the proposed passive equivalent circuit models have been found to be the convenience and versatile tools for the implementation of any analog and mixed signal processing circuits and systems.

The crosstalk phenomenon, wich occurs between transmission lines, is caused by electromagnetic fields of currents flowing through the lines. Crosstalk between two bent lines is studied by using a set of solutions of modified telegrapher's equations. By expressing electromagnetic fields in terms of voltages and currents in the line ends, the resultant network function in the form of an ABCD matrix is obtained. Electromagnetic fields caused by currents flowing in risers at transmission line ends are taken into account in addition to those fields in line sections. The validity of the proposed approach was confirmed by comparing experimental results with computed results and those simulated by a commercial electromagnetic solver for some bent-line models.

Substrate-coupling equivalent circuits can be derived for arbitrary isolation structures by F-matrix computation. The derived netlist represents a unified impedance network among multiple sites on a chip surface as well as internal nodes of isolation structures and can be applied with SPICE simulation to evaluate isolation strengths. Geometry dependency of isolation attributes to layout parameters such as area, width, and location distance. On the other hand, structural dependency arises from vertical impurity concentration specific to p+/n+ diffusion and deep n-well. Simulation-based prototyping of isolation structures can include all these dependences and strongly helps establish an isolation strategy against high-frequency substrate coupling in a given technology. The analysis of isolation strength provided by p+/n+ guard ring, deep n-well guard ring as well as deep n-well pocket well explains S21 measurements performed on high-frequency test structures targeting 5 GHz bandwidth, that was formed in a 0.25-µm CMOS high frequency.

A new analytical approach which reveals relationships between resonator parameters (unloaded Q-factor, coupling coefficient, and loaded Q-factor) and phase noise in microwave negative-resistance oscillators is presented. On the basis of Kurokawa's theory, this approach derives analytical expressions for the phase noise as a function of the resonator parameters (with particular emphasis on the coupling coefficient). Two types of negative-resistance oscillators--classified according to the manner in which the resonator is used in a circuit--are analyzed. These analyses use realistic circuit configurations and design procedures. The passive network connecting the active device and the resonator, which is shown to have important effects on the above-mentioned relationship, is taken into account. Validity of the new approach is verified through harmonic-balance simulations. The presented analytical approach can provide useful guidelines for choosing the resonator parameters, especially the value of the coupling coefficient, when designing microwave negative-resistance oscillators.

First we introduce the high-frequency equivalent circuit model of the Fine Pitched Ball Grid Array (FPBGA) bonding for frequencies up to 20 GHz. The lumped circuit model of the FPBGA bonding was extracted based on S-parameters measurement and subsequent fitting of the model parameters. The test packages, which contain probing pads, coplanar waveguides and FPBGA ball bonding, were fabricated and measured. The suggested π-model of the FPBGA bonding consists of self-inductor, self-capacitor, and self-resistor components. From the extracted model, a solder ball of 350 µm diameter and 800 µm ball pitch has less than 0.08 nH self-inductance, 0.40 pF self capacitance, and about 10 mΩ self-resistance. In addition, the mutual capacitance caused by the presence of the adjacent bonding balls is included in the model. The FPBGA solder ball bonding has less than 1.5 dB insertion loss up to 20 GHz, and it causes negligible delay time in digital signal transmission. The extracted circuit model of FPBGA bonding is useful in design and performance simulation of advanced packages, which use FPBGA bonding.

Finite-ground microstrip line (FGMSL) open-end discontinuities are characterized via a self-calibrated method of moments (MoM) as a unified circuit model with a fringing capacitance and radiation conductance. By integrating the short-open calibration (SOC) procedure into a determinant MoM, the model parameters are extracted without needing the alternative port impedance. Regardless of non-ideal voltage sources, extracted parameters are observed to achieve a stable convergence as the feeding line is sufficiently extended. After extracted capacitance of a FGMSL open-end with equal strip and finite-ground widths are validated against its traditional MSL counterpart with infinite ground, extensive results are given to originally demonstrate that the capacitance increases as a decelerated function of the finite-ground width and length while the conductance is negligibly small as compared with its imaginary part.

Field-theoretical equivalent circuit models of a variety of coplanar waveguide (CPW) lumped-element discontinuities for two dominant modes are characterized by executing the short-open calibration (SOC) procedure in the fullwave method of moments (MoM). In our developed MoM platform, the impressed current sources with even or odd symmetry are introduced at the selected ports in order to separately excite the even and odd dominant modes, i.e., CPW- and CSL-mode. After the port network parameters are numerically derived using the Galerkin's technique, the two SOC standards are defined and evaluated in the self-consistent MoM to effectively de-embed and extract the core model parameters of a CPW circuit or discontinuity. After the validation is confirmed via comparison with the published data, extensive investigation is carried out to for the first time demonstrate the distinctive model properties of one-port CPW short- and open-end elements as well as two-port inductive and capacitive coupling elements with resorting to its two different dominant modes.

This paper proposes an operation-region model for analyzing and testing analog and mixed-signal circuits, which is based on observation of change in MOSFET operation regions. First, the relation between the change in MOSFET operation regions and the fault behavior of a mixed-signal circuit containing a bridging fault is investigated. Next, we propose an analysis procedure based on the operation-region model and apply it to generate the optimal input combination for testing the circuit. We also determine which transistors should be observed in order to estimate the circuit behavior. Since the operation-region model is a method for modeling circuit behavior abstractly, the proposed method will be useful for modeling circuit behavior and for analyzing and testing many kinds of analog and mixed-signal circuits.

During past decade MOS transistors have been aggressively scaled to dimensions below sub-quarter micron, the so called ultra deep submicron (UDSM) technology. At these dimensions transistor characteristics can not be accurately modeled using classical approach presently used in the most commonly used MOSFET models such as BSIM3, MOS9 etc, without recourse to large number of empirical parameters. In this paper we will discuss short comings of the present models and show how to overcome them using a hybrid approach of modeling, wherein both function regional and surface potential based approaches are combined together, that results in a model that reflects UDSM device behavior with smaller set of physically meaningful, and easily extractable model parameters. Various physical effects that need to be considered for UDSM modeling such as quantization of the inversion layer carrier, mobility degradation, carrier velocity saturation and overshoot, polydepletion effect, bias dependent source/drain resistance, vertical and lateral doping profiles, etc. will be discussed.

It is of significantly importance in relation to the problem of diagnosis of deviation faults in linear analog circuits to check whether or not it is possible to uniquely determine the element-values in a given linear analog circuit from the node-voltage measurements at its accessible nodes and then of giving a method for actual computation of the element-values if it is possible, under the assumption that i) the circuit is of known topology (and of known element-kinds if possible) and ii) the actual value of each element-value of the circuit almost always deviates from the design value and is not known exactly. In this paper, the problem of checking the unique determinability of the element-values is called the element-value determinability problem, and its solutions which have been obtained until now are reviewed in perspectives to designing a publicly available user-oriented analog circuit diagnosis system.