Mahmoud A. El Nokali

A thermal model for insulated gate bipolar transistor module

A thermal resistor-capacitor (RC) model is introduced for the power insulated gate bipolar transistor (IGBT) modules used in a three-phase inverter. The parameters of the model are extracted from the experimental data for the transient thermal impedance from-junction-to-case Z/sub jc/ and case-to-ambient Z/sub ca/. The accuracy of the RC model is verified by comparing its predictions with those resulting from the three-dimensional finite element method simulation. The parameter extraction algorithm is easy to adapt to other types of power modules in an industrial application environment.

Automated PSpice simulation as an effective design tool in teaching power electronics

In this paper, PSpice is used to deepen the student understanding of power electronics and to serve as a design tool for power converter circuits. A library that includes automated versions of dc/dc converters and rectifiers is built in PSpice using ideal switches. The automated version permits students to design converter circuits that meet a set of design criteria. The performance of various designs are tested by plotting the current and voltage waveforms using the graphics postprocessor Probe. The library was introduced to students in a power electronics course, and they have been asked to augment its contents through mini-design projects. The response was positive, which will encourage the extension of the approach to other subjects.

A parameter extraction algorithm for an IGBT behavioral model

We propose a new extraction algorithm for the parameters of an insulated gate bipolar transistor dynamic behavioral model. The algorithm relies on the availability of experimental data from the manufacturers and uses Matlab optimization toolbox to extract the parameters automatically. The theoretical predictions of the algorithm are compared with both the experimental and the simulation data that use alternative extraction methods and are found to be in excellent agreement.

A new IGBT behavioral model

Abstract In this paper, we present a new behavioral model valid for insulated gate bipolar transistors (IGBTs). The d.c. part of the model is based on an empirical formula for the IGBT and needs three data points on the I – V curves to generate the entire d.c. characteristics. The dynamic part of the model is based on a Hammerstein-like current source. A template written in the MAST language is created in Saber simulator based on this new model. The theoretical predictions of the model are compared with the experimental data available for IGBTs fabricated by various manufacturers and found to be in excellent agreement. Furthermore, the new model is consistently faster than the existing physical models in simulating various circuit topologies.

A unified I-V model for PD/FD SOI MOSFETs with a compact model for floating body effects

Abstract In this paper, a unified analytical I–V model for silicon-on-insulator (SOI) MOSFET is presented. The model is valid for possible transitions between partially depleted and fully depleted modes during the transistor operation. It is based on a non-pinned surface potential approach that is valid for all regions of operation. Small geometry effects such as channel length modulation and high field mobility effects are also included. It also considers the self-heating effect, which is important for complete modeling of SOI devices. To include the floating body effect, the parasitic current in each mode of operation is modeled with a proper formulation while a smoothing function is invoked for the transition between the operation modes. A comparison between the model and the experimental results shows good agreement over a wide range of drain and gate voltages.

A TRANSIENT MODEL FOR INSULATED GATE BIPOLAR TRANSISTORS (IGBTs)

In this paper, we present a physics-based model for the non punch-through (NPT) insulated gate bipolar transistor (IGBT) during transient turn off period. The steady state part of the model is derived from the solution of the ambipolar diffusion equation in the drift region of the NPT IGBT. The transient component of the model is based on the availability of a newly developed expression for the excess carrier concentration in the base. The transient voltage and current are obtained both numerically and analytically from this model. The theoretical predictions of both approaches are compared with experimental data and found to be in good agreement.

D.C. characteristic of MESFETs at High Temperatures

Abstract The ability of GaAs MESFET to operate over a wide temperature range requires accurate models to simulate the temperature dependence of various device parameters. In this paper, a new analytical model for the threshold voltage of MESFETs operating beyond 250°C is introduced. The model takes into account the effect of the gate leakage current on threshold voltage and is used successfully to overcome the shortcomings of existing models in the literature in matching the experimental data at temperatures higher than 250°C. The model is used to predict the drain current dependence on temperature in both the subthreshold and saturation region.

A physically based approach for the calculation of the scattering parameters in high electron mobility transistors

This paper is intended to show that there is a good fit between the measured and the modelled parameters for the HEMTs. These parameters include the components of the scattering and admittance matrices, the operating power gain, the transducer power gain and the maximum stable gain for the device. The modelled parameters are based on the physics of the device and include second-order effects such as a mobility degradation, velocity saturation as well as the conduction in the AlGaAs layer.

A compact modeling of drain current in PD/FD SOI MOSFETs

In this paper, a unified analytical I-V model for silicon-on-insulator (SOI) MOSFET is presented. The model is valid for possible transitions between partially-depleted (PD) and fully-depleted (FD) modes during the transistor operation. It is based on a non-pinned surface potential approach that is valid for all regions of operation. The surface potential is calculated accurately and efficiently in this model where small geometry effects such as channel length modulation (CLM) and high field mobility effects are also included. It also considers the self-heating effect, which is important for complete modeling of SOI devices. For including the floating body effect, the parasitic currents in each mode of operation is modeled with a proper formulation while a smoothing function is invoked for the transition between the operation modes. A comparison between the model and the experimental results shows good agreement over a wide range of drain and gate voltages.

A fast numerical algorithm for heterojunction structures

In this paper, the two-dimensional electron gas (2DEG) concentration is numerically calculated for single and double heterostructure band profiles by solving Schroödingers and Poissons equations self-consistently. An expected energy level is introduced to enhance the speed of calculation in obtaining quantized energy levels through the iteration process. Conventional AlGaAs/GaAs and AlGaAs/InGaAs/GaAs structures are selected to prove the validity of this calculation. Three different concentrations, namely, positively ionized donors, free electrons in the conduction band and 2DEG, are considered through the band profiles. Both the 2DEGs in the narrow bandgap and free electrons in the wide bandgap have been calculated and compared with the data available in the literature. Furthermore, positively ionized donors are also obtained and correlated with 2DEG and free electrons to predict the gate capacitance characteristics of the devices, and showed good agreement with the experimental data.