A. J. Wilkinson

Automated Model Generation Algorithm for High-Level Fault Modeling

High-level modeling for operational amplifiers (opamps) has been previously carried out successfully using models generated by published automated model generation approaches. Furthermore, high-level fault modeling (HLFM) has been shown to work reasonably well using manually designed fault models. However, no evidence shows that published automated model generation approaches based on opamps have been used in HLFM. This paper describes HLFM for analog circuits using an adaptive self-tuning algorithm called multiple model generation system using delta. The generation algorithms and simulation models were written in MATLAB and the hardware description language VHDL-AMS, respectively. The properties of these self-tuning algorithms were investigated by modeling complementary metal-oxide-semiconductor opamps, and comparing simulations using the HLFM against those of the original simulation program with integrated circuit emphasis circuit utilizing transient analysis. Results show that the models can handle both linear and nonlinear fault situations with better accuracy than previously published HLFMs.

Wrapping strategies for temperature control of chilled foodstuffs during transport

There is a growing market for food producers to supply their goods direct to customers, which has largely been brought about by the growing popularity of web-based ordering. However, the geographical distance between supplier and consumer can be large and this presents problems if temperature-sensitive foods are to be transported. Here we describe a numerical model for the thermal experience of foodstuff packaged in expanded polystyrene boxes in the presence of a gel refrigerant. The model is validated by comparing predicted temperatures with those measured in the laboratory, and the model is then used to investigate the effect that the quantity and placement of gel refrigerant and the ambient temperature have on the period for which maximum food temperature can be maintained below 5°C and 8°C. Results indicate that it is possible to maintain chilled food below these temperatures for up to 24 h, though this period is dependent upon ambient temperature, the manner in which the refrigerant is wrapped around the food and the position of a food item inside the box.

A phase modulation-based ultrasonic communication system using Variable Structure Control

Narrow bandwidth transducers used in existing ultrasonic data communication systems are known to be devices with a high Q resonant response and low coupling to both the electrical drive and acoustic output interfaces. These features limit the speed of phase change when phase modulation (PM) is used. This paper studies the design of a Variable Structure Controller (VSC)-based transmitter with the aim of increasing the capacity of a PM-based communications system. Simulation results are presented to demonstrate the potential of this approach.

A robust approach for automated model generation

Over the last few years, automated model generation approaches have rapidly gained importance as a sustainable methodology for verification of large, complex mix-signal SoCs (system-on-chips) and SiPs (system-in-packages). In this paper a novel approach termed multiple model generation system using Delta operator (MMGSD) is developed for extracting either single-input single-output (SISO) or multiple-input single-output (MISO) macromodels from a SPICE netlist. This model generation process detects nonlinearity through variations in output error. The objective of using delta operator is to achieve transient impulse invariant transform. Examples of the application of MMGSD are presented for simple two-input systems incorporating a two-stage CMOS operational amplifier (op amp). We demonstrate the generated models are able to model various circuits with good accuracy.

A novel approach for automated model generation

Automatic approaches for macromodel generation from SPICE-level descriptions have been of great interest over the last few years for the design of large, complex mix- signal SoCs (system-on-chips) and SiPs (system-in-packages). In this paper a novel approach termed multiple model generation system (MMGS) is developed for extracting either single-input single-output (SISO) or multiple-input single-output (MISO) macromodels from a SPICE netlist. This model generation process detects nonlinearity through variations in output error. Examples of the application of MMGS are presented for simple two-input systems incorporating a two-stage CMOS operational amplifier (op amp).

An investigation of the sensitivity of embedded passive component temperatures to PCB structure

The embedding of passive components such as resistors, capacitors and inductors within printed circuit boards (PCBs) is motivated, to a large extent, by the desire for increased miniaturization of electronic goods. However, resistors and, to a lesser extent, inductors are heat generating devices, and the temperature developed within PCBs as the result of the operation of embedded passives is an important aspect of multilayer PCB design. Many factors can influence the generation of heat inside such embedded structures, and, in this paper, validated numerical simulations are used to investigate the temperature rises associated with embedded resistors. Sensitivity of temperature rises to PCB structural changes are investigated in terms of embedded resistor temperature and in terms of interaction with other neighboring components on the same and adjacent component layers.

Automated macromodel generation for high level modeling

In this paper we present a novel approach termed multiple model generation system (MMGS) for extracting either single-input single-output (SISO) or multiple- input single-output (MISO) macromodels from a SPICE netlist. It detects nonlinearity through variations in output error. The multiple model conversion system (MMCS) is developed to automatically convert these models from MMGS into hardware description language (HDL) models for either SISO or MISO macromodels and behave as the operational amplifier (op amp). We demonstrate the application of MMGS using a two-stage CMOS operational amplifier (op amp), comparing simulations of the macromodel against those of the original SPICE circuit utilizing transient analysis.

Performance analysis of a phase modulation-based ultrasonic receiver using Variable Structure Control

A previous paper introduced an ultrasonic (US) transducer driven using Variable Structure Control (VSC) as part of a phase modulated communication system. This paper presents a receiver system also using VSC. The system aims to minimize transducer oscillation with the feedback control signal providing the output. Simulations show a receiver capable of responding within 50 µs to a phase reversal in the 40 kHz acoustic input.

Numerical simulation of embedded passive components in multi‐layer PCB structures

Numerical modelling is used to predict the thermal behaviour of embedded passive components in multi‐layer PCBs. A three‐signal layer PCB, containing embedded resistors of dimensions 0.3 6 0.3mm and thickness 0.1μm, is used to generate thermal design rules that can be applied to a wide range of PCB structures containing embedded passive components. A software package using the design rules can then make fast predictions on the thermal behaviour of heat‐generating components inside such structures.

Discretization effects in TLM diffusion models

The standard methods for bringing a TLM diffusion model to convergence are necessary but tedious. However, much time and effort can be saved if the initial choices of elemental size and iteration timestep are appropriate. Here we consider the general form of the solution to the diffusion equation and sample the component dynamics to determine the impulse invariant response. We then derive a convenient method for charting the discrepancy between the coefficients of the continuous description and the impulse invariant transformation, as this discrepancy varies with discretization of space and time. The use of the curves in estimating appropriate elemental size and iteration timestep is described. Copyright