Instantaneous model of a MESFET for use in linear and nonlinear circuit simulations

A formal approach for nonlinear modeling of FETs is presented. The intrinsic transistor is described by current and charge generators, that are instantaneously dependent on the two internal voltages. The extrinsic parasitic elements are also included. This instantaneous model is obtained from the small signal equivalent circuit computed at a number of bias points, by integration of the bias dependent elements. A program for using this model in nonlinear circuit analysis has been developed. The process has been carried out for two transistors, one being of low noise, and the other a power MESFET. Good agreement has been observed when comparing the nonlinear analysis with measured data. A solid-state power amplifier at 28 GHz has been designed using the power transistor, delivering 21 dBm at 1 dB compression point.Peer ReviewedPostprint (published version

Interpolation-based parameterized model order reduction of delayed systems

Three-dimensional electromagnetic methods are fundamental tools for the analysis and design of high-speed systems. These methods often generate large systems of equations, and model order reduction (MOR) methods are used to reduce such a high complexity. When the geometric dimensions become electrically large or signal waveform rise times decrease, time delays must be included in the modeling. Design space optimization and exploration are usually performed during a typical design process that consequently requires repeated simulations for different design parameter values. Efficient performing of these design activities calls for parameterized model order reduction (PMOR) methods, which are able to reduce large systems of equations with respect to frequency and other design parameters of the circuit, such as layout or substrate features. We propose a novel PMOR method for neutral delayed differential systems, which is based on an efficient and reliable combination of univariate model order reduction methods, a procedure to find scaling and frequency shifting coefficients and positive interpolation schemes. The proposed scaling and frequency shifting coefficients enhance and improve the modeling capability of standard positive interpolation schemes and allow accurate modeling of highly dynamic systems with a limited amount of initial univariate models in the design space. The proposed method is able to provide parameterized reduced order models passive by construction over the design space of interest. Pertinent numerical examples validate the proposed PMOR approach

Modeling Solder Ball Array Interconnects for Power Module Optimization

PowerSynth is a software platform that can co-optimize power modules utilizing a 2D topology and wire bond interconnects. The novel 3D architectures being proposed at the University of Arkansas utilize solder ball interconnects instead of wire bonds. Therefore, they currently cannot be optimized using PowerSynth. This paper examines methods to accurately model the parasitic inductance of solder balls and ball grid arrays so they may be implemented into software for optimization. Proposed mathematical models are validated against ANSYS Electromagnetics Suite simulations. A comparison of the simulated data shows that mathematical models are well suited for implementation into optimization software platforms. Experimental measurements proved to be inconclusive and necessitate future work

Indoor Wireless RF Energy Transfer for Powering Wireless Sensors

For powering wireless sensors in buildings, rechargeable batteries may be used. These batteries will be recharged remotely by dedicated RF sources. Far-field RF energy transport is known to suffer from path loss and therefore the RF power available on the rectifying antenna or rectenna will be very low. As a consequence, the RF-to-DC conversion efficiency of the rectenna will also be very low. By optimizing not only the subsystems of a rectenna but also taking the propagation channel into account and using the channel information for adapting the transmit antenna radiation pattern, the RF energy transport efficiency will be improved. The rectenna optimization, channel modeling and design of a transmit antenna are discussed

Variable-fidelity electromagnetic simulations and co-kriging for accurate modeling of antennas

Accurate and fast models are indispensable in contemporary antenna design. In this paper, we describe the low-cost antenna modeling methodology involving variable-fidelity electromagnetic (EM) simulations and co-Kriging. Our approach exploits sparsely sampled accurate (high-fidelity) EM data as well as densely sampled coarse-discretization (low-fidelity) EM simulations that are accommodated into one model using the co-Kriging technique. By using coarse-discretization simulations, the computational cost of creating the antenna model is greatly reduced compared to conventional approaches, where high-fidelity simulations are directly used to set up the model. At the same time, the modeling accuracy is not compromised. The proposed technique is demonstrated using three examples of antenna structures. Comparisons with conventional modeling based on high-fidelity data approximation, as well as applications for antenna design, are also discussed

A circuit modeling technique for the ISO 7637-3 capacitive coupling clamp test

In this paper, we propose a transmission-line modeling technique for the ISO 7637-3 capacitive coupling clamp (CCC) test. Besides modeling the test bench, special attention is devoted to the CCC itself, for which an equivalent circuit is constructed based on the concept of surface transfer impedance and surface transfer admittance. The overall model is validated by means of measurements using a nonlinear circuit as device-under-test, as such demonstrating the appositeness to mimick the CCC test in simulations during the design phase

System level power integrity transient analysis using a physics-based approach

With decreasing supply voltage level and massive demanding current on system chipset, power integrity design becomes more and more critical for system stability. The ultimate goal of well-designed power delivery network (PDN) is to deliver desired voltage level from the source to destination, in other words, to minimize voltage noise delivered to digital devices. The thesis is composed of three parts. The first part focuses on-die level power models including simplified chip power model (CPM) for system level analysis and the worst scenario current profile. The second part of this work introduces the physics-based equivalent circuit model to simplify the passive PDN model to RLC circuit netlist, to be compatible with any spice simulators and tremendously boost simulation speed. Then a novel system/chip level end-to-end transient model is proposed, including the die model and passive PDN model discussed in previous two chapters as well as a SIMPLIS based small signal VRM model. In the last part of the thesis, how to model voltage regulator module (VRM) is explicitly discussed. Different linear approximated VRM modeling approaches have been compared with the SIMPLIS small signal VRM model in both frequency domain and time domain. The comparison provides PI engineers a guideline to choose specific VRM model under specific circumstances. Finally yet importantly, a PDN optimization example was given. Other than previous PDN optimization approaches, a novel hybrid target impedance concept was proposed in this thesis, in order to improve system level PDN optimization process --Abstract, page iv

Multi-phase state estimation featuring industrial-grade distribution network models

This paper proposes a novel implementation of a multi-phase distribution network state estimator which employs industrial-grade modeling of power components and measurements. Unlike the classical voltage-based and current-based state estimators, this paper presents the implementation details of a constrained weighted least squares state calculation method that includes standard three-phase state estimation capabilities in addition to practical modeling requirements from the industry; these requirements comprise multi-phase line configurations, unsymmetrical and incomplete transformer connections, power measurements on 4-connected loads, cumulative-type power measurements, line-to-line voltage magnitude measurements, and reversible line drop compensators. The enhanced modeling equips the estimator with capabilities that make it superior to a recently presented state-of-the-art distribution network load estimator that is currently used in real-life distribution management systems; comparative performance results demonstrate the advantage of the proposed estimator under practical measurement schemes