Small-signal modeling of a single-switch AC/DCpower-factor-correction circuit

In this paper, a small-signal model for a new single-switch single-stage switched-mode power-factor-correction (PFC) converter is presented. The model is obtained by applying the small-signal perturbation technique to the circuit equations derived from the state-space averaging method. By applying the perturbation and averaging techniques over one switching cycle, the DC and small-signal equivalent circuit representations of this converter are derived. The result shows that this converter exhibits the transfer characteristics of a second-order low-pass system for the output-to-input transfer function and that of a combined second-order low-pass and band-pass system for the output-to-control transfer function. The validity of the proposed mathematical model was verified by the given experimental results for a specified design example     

Small-signal admittance of a Gunn-effect device

A small-signal equivalent circuit of a Gunn-effect device is deduced from a simple model. Preliminary measurements substantiate this equivalent circuit. The results are used to calculate the small-signal admittance of a 1?cm GaAs Gunn-effect device at 10 Gc/s.     

Improved small-signal equivalent circuit model and large-signalstate equations for the MOSFET/MODFET wave equation

A simple non-quasi-static small-signal equivalent circuit model is derived for the ideal MOSFET wave equation under the gradual channel approximation. This equivalent circuit represents each Y-parameter by its DC small-signal value shunted by a (trans) capacitor in series with a charging (trans) resistor. A large-signal model for the intrinsic MOSFET is derived by first implementing this RC topology in the time domain. Modified state equations are then introduced to enforce charge conservation. Transient simulations with this approximate large-signal model yield results that are compared with reported exact numerical analysis for the long channel MOSFET for a wide range of bias conditions. This unified small- and large-signal model applies to both the three- and four-terminal intrinsic MOSFET in the region of the channel where the gradual channel approximation is applicable. A non-quasi-static small-signal equivalent circuit for the velocity-saturated MOSFET wave equation is also reported     

Circuit Characterization of V-Band IMPATT Oscillators and Amplifiers

A circuit model has been developed to describe a class of commonly used waveguide cavities for V-band IMPATT oscillators and amplifiers. Calculated results based on this model used in conjunction with theoretical small-signal IMPATT characteristics have shown good qualitative agreement with experimental data. Detailed characterization of a small-signal V-band IMPATT amplifier and a mechanical tuned oscillator are presented, and the predicted performance is compared with measurements.     

Analysis and Design for a Novel Single-Stage High Power Factor Correction Diagonal Half-Bridge Forward AC–DC Converter

By means of components placement, the buck-boost and diagonal half-bridge forward converters are combined to create a novel single-stage high power factor correction (HPFC) diagonal half-bridge forward converter. When both the PFC cell and dc–dc cell operate in DCM, the proposed converter can achieve HPFC and lower voltage stress of the bulk capacitor. The circuit analysis of the proposed converter operating in$ DCM+ DCM$mode is presented. In order to design controllers for the output voltage regulation, the ac small-signal model of the proposed converter is derived by the averaging method. Based on the derived model, the proportional integral (PI) controller and minor-loop controller are then designed. The simulation and experimental results show that the proposed converter with the minor-loop controller has faster output voltage regulation than that with the PI controller despite the variations of line voltage and load. Finally, a 100-W prototype of the proposed ac–dc converter is implemented and the theoretical result is experimentally verified.     

太赫兹平面肖特基二极管参数模型

根据太赫兹平面肖特基二极管物理结构,在理想二极管SPICE参数模型的基础上建立了二极管小信号等效电路模型。依据该二极管等效电路模型设计了基于共面波导（CPW）去嵌方法的二极管S参数在片测试结构,并对其在0.1~50 GHz、75~110 GHz频率范围内进行了高频小信号测试,利用测试结果提取了高频下二极管电路模型中各部分电容、电阻以及电感参数。将相应的高频下电容与电阻参数分别与低频经验公式电容值和直流I-V测试提取的电阻值进行了对比,并利用仿真手段对高频参数模型进行了验证。完整的参数模型以及测试手段相较于理想二极管SPICE模型和传统的参数提取方法可以更为准确地表征器件在高频下的工作状态。该建模思路可用于太赫兹频段非线性电路的优化设计。     

State-Space Analysis of General IMPATT Diode Small-Signal Lumped Models

The development of a lumped model for small-signal carrier-field interactions in an IMPATT diode results in a set of state equations. Using state-space analysis techniques, the equations are solved for the small-signal impedance of a general IMPATT diode as a function of dc bias current and frequency. Read, p-n, and p-i-n diodes are studied using realistic values for saturation carrier velocities and carrier-ionization rates. Curves indicating the influence of diode physical properties on the small-signal impedance are presented. By combining state equations describing the behavior of the external microwave circuit with the diode state equations, the small-signal oscillation frequency and threshold dc bias current of a coaxial IMPATT oscillator are determined.     

Unified model of PWM switch including inductor in DCM

The conventional small-signal circuit model in the discontinuous conduction mode (DCM) shows large discrepancies at high frequencies. A new unified small-signal circuit model of the pulsewidth modulation (PWM) switch including inductor in the DCM is proposed to overcome the inaccuracy of the conventional small-signal circuit model     

A General Approach to Sampled-Data Modeling for Power Electronic Circuits

A general sampled-data representation of the dynamics of arbitrary power electronic circuits is proposed to unify existing approaches. It leads, via compact and powerful notation, to disciplined modeling and straightforward derivation of small-signal models that describe perturbations about a nominal cyclic steady state. Its usefulness is further illustrated by considering the representation and analysis of a class of symmetries in circuit operation. The results of the application of this methodology to modeling the small-signal dynamics of a series resonant converter are described. The results correlate well with simulation results obtained on the Massachusetts Institute of Technology's Parity Simulator. What is of greater significance is the fact that the small-signal model is obtained in a completely routine way, starting from a general formulation and working down to the actual circuit; this contrasts with the circuit-specific analyses that are more typical of the power electronics literature. The automatability of this procedure is also discussed, and it is pointed out that the key ingredients for automatic generation of dynamic models from a circuit specification are now available.     

Symbolic Macromodeling for Statistical Simulation of Operational Amplifiers

Symbolic circuit simulator is traditionally applied to the small-signal analysis of analog circuits. This paper establishes a symbolic behavioral macro-modeling method applicable to both small-signal and large-signal analysis of general two-stage operational amplifiers (op-amps). The proposed method creates a two-pole parametric macromodel whose parameters are analytical functions of the circuit element parameters generated by a symbolic circuit simulator. A moment matching technique is used in deriving the analytical model parameter. The created parametric behavioral model can be used for op-amps performance simulation in both frequency and time domains. In particular, the parametric models are highly suited for fast statistical simulation of op-amps in the time-domain. Experiment results show that the statistical distributions of the op-amp slew and settling time characterized by the proposed model agree well with the transistor-level results in addition to achieving significant speedup.     

Asymmetrical Oscillations in Digitally Controlled Power-Factor-Correction Boost Converters

Digitally controlled power-factor-correction (PFC) converters are essentially piecewise-smooth nonlinear systems due to their switching action. However, their complex behavior almost remains unexplored. Unlike analog control, digital control introduces a time delay due to the sample-and-hold and the digital computation. Here, a small-signal model that takes the time delay into account is derived to judge the stability of a digitally controlled PFC boost converter. It is proven that the time delay seriously degrades the converter's stability. After the inner current loop and/or the outer voltage loop lose stability, we experimentally discover that oscillations begin to occur, and the oscillations are asymmetrical. Such an asymmetry can be interpreted by the underdevelopment characteristic of the dynamical behavior in the digitally controlled PFC boost converter. The results reported in this brief offer more knowledge about the dynamical behavior in digitally controlled PFC converters.      

An investigation of the power characteristics and saturationmechanisms in HEMTs and MESFETs

A method for large-signal transistor analysis is presented. The method is based on the harmonic-balance approach but makes use of input data from measured S-parameters instead of DC or pulsed DC characteristics and a large-signal equivalent circuit with harmonic elements. The topology of this circuit is nearly identical to commonly used small-signal equivalent circuits; its application allows a detailed interpretation of the computed results, which are very precise due to the use of small-signal S-parameters. The large-signal model is applied to HEMTs and MESFETs. Their saturation mechanisms are investigated and the operational difference is discussed. The importance of including higher harmonic signal components in the large-signal analysis is also shown     

Physical modeling of GaAs MESFETs in an integrated CAD environment:from device technology to microwave circuit performance

The linkage between a physical device simulator for small- and large-signal characterization and CAD (computer-aided design) tools for both linear and nonlinear circuit analysis and design is considered. Efficient techniques for the physical DC and small-signal analysis of MESFETs are presented. The problem of physical simulation in a circuit environment is discussed, and it is shown how such a simulation makes possible small-signal models accounting for propagation and external parasitics. Efficient solutions for physical large-signal simulation, based on deriving large-signal equivalent circuits from small-signal analyses under different bias conditions, are proposed. The small- and large-signal characterizations allow physical simulation to be performed efficiently in a circuit environment. Examples and results are presented     

A complete small-signal equivalent circuit model of cooled butterfly-type 2.5 Gbps DFB laser modules and its application to improve high frequency characteristics

A small-signal equivalent circuit model of 2.5 Gbps DFB laser modules with butterfly-type dual-in-line packages has been proposed and verified using extracted parameters. Parameters related to the equivalent circuit have been extracted from measured S parameters using the modified two-port black box model. This model includes small-signal equivalent circuits of components used for 2.5 Gbps DFB laser modules such as DFB laser, coplanar waveguides, matching resistor, bonding wires, and thermoelectric cooler (TEC). From this equivalent circuit modeling, we show that calculated frequency characteristics of DFB lasers on submount and complete DFB laser modules are similar to their measured frequency characteristics, respectively. Based on this equivalent circuit model, we propose and demonstrate a method that can improve frequency characteristics of 2.5 Gbps DFB laser modules through both experiments and simulations.     

Electron Device Model Parameter Identification Through Large-Signal-Predictive Small-Signal-Based Error Functions

Empirical electron device models based on lumped equivalent circuits are usually identified through nonlinear optimization procedures, which are based on the best fitting between the extrinsic model behavior and measurements carried out under multibias static and small-signal excitations. In this paper, a new error function is proposed for equivalent circuit model parameter optimization. Although still being defined through standard static and small-signal measurement data, the new error function can be configured so as to obtain models tailored to specific large-signal applications. Experimental results, which confirm the validity of the proposed identification approach, are provided for a GaAs microwave pseudomorphic HEMT model aimed at the design of highly linear power amplifiers.     

Simulator-independent compact modeling of vertical npn transistors for ESD and RF circuit simulation

We present an easy-to-use, simulator-independent compact model of a vertical npn transistor suitable for ESD circuit simulation. In addition to including high-current and breakdown effects, we also model accurately the small-signal off-state impedance of the device using s-parameter measurements, for inclusion in RF circuit simulations. Experimental results are provided for silicon and SiGe npn transistors.     

An efficient CAD-oriented large-signal MOSFET model

An efficient computer-aided-design-oriented large-signal microwave model for silicon MOSFETs is presented based on the well-founded small-signal equivalent circuit including self-heating effect and charge conservation condition. The proposed new single continuously differentiable empirical equations for drain current and gate capacitance are simple and quite accurate. The model parameters in the equations are constructed in such a way that they can be easily and straightforwardly extracted from measured data. The temperature effect is predicted by simply adopting the linear temperature-dependent model parameters for threshold voltage, saturation current, capacitance, and series resistances. The presented model is a good compromise between the simplicity of numerical calculations and the accuracy of final results that is desired by circuit designers in nonlinear circuit simulation     

考虑速度过冲效应的HEMT物理模型

本文提出了一种考虑这冲效应的ＨＥＭＴ器件静态和小信号解析物理模型。通过对栅极下面道中造近源端附近的电场采用弱强梯场近似，提出了一个半经验的速度过冲模型，在非线性电荷控制模型的基础上述导出了基于物理参数的ＨＥＭＴ器件电流－电压特性和小等效电路参数的解析表达式。实际计算结果与测得数据比较表明，本模型具有比较高的精度。