Alan Mantooth

Power SiC DMOSFET Model Accounting for Nonuniform Current Distribution in JFET Region

The main goal of this paper is development of a new circuit-based silicon carbide (SiC) DMOSFET model which physically represents the mechanism of current saturation in power SiC DMOSFET. Finite-element simulations show that current saturation for a typical device geometry is due to 2-D carrier distribution effects in the JFET region caused by current spreading from the channel to the JFET region. For high drain-source voltages, most of the voltage drop occurs in the current spreading region located in the JFET region close to the channel. A new model is proposed that represents the nonuniform current distribution in the JFET region using a nonlinear voltage source and a resistance network. Advantages of the proposed model are that a single set of equations describes operation in both the linear and saturation regions, and that it provides a more physical description of MOSFET operation.

A high voltage Dickson charge pump in SOI CMOS

An improved charge pump that utilizes a MOSFET body diode as a charge transfer switch is discussed. The body diode is characterized and a body diode model is developed for simulating the charge pump circuit. An increase in voltage pumping gain for a silicon-on-insulator (SOI) Dickson charge pump is demonstrated when compared with a traditional bulk CMOS Dickson charge pump. A 6-stage Dickson charge pump was designed to produce a 20 V output from a 3.3 V supply, using a 4 MHz, two-phase non-overlapping clock signal driving the charge pump. The design was fabricated in a 0.35 /spl mu/m partially depleted SOI CMOS process. An efficiency of 72% is achieved at a load current of approximately 20 /spl mu/A.

A 4H Silicon Carbide Gate Buffer for Integrated Power Systems

A gate buffer fabricated in a 2-μm 4H silicon carbide (SiC) process is presented. The circuit is composed of an input buffer stage with a push-pull output stage, and is fabricated using enhancement mode N-channel FETs in a process optimized for SiC power switching devices. Simulation and measurement results of the fabricated gate buffer are presented and compared for operation at various voltage supply levels, with a capacitive load of 2 nF. Details of the design including layout specifics, simulation results, and directions for future improvement of this buffer are presented. In addition, plans for its incorporation into an isolated high-side/low-side gate-driver architecture, fully integrated with power switching devices in a SiC process, are briefly discussed. This letter represents the first reported MOSFET-based gate buffer fabricated in 4H SiC.

Power-CAD: A novel methodology for design, analysis and optimization of Power Electronic Module layouts

Power Electronic Module (PEM) design requires simultaneous analysis of thermal, electrical, and mechanical parameters to design an optimal layout. The current design process being used by package designers involves a sequential procedure instead of a simultaneous process. Each design step involves the analysis of the thermal, electrical or mechanical aspects of the design. As a result, the designer has to iterate between the various design process steps in order to achieve an optimal design. This causes a substantial increase in the design cycle time. A new methodology has been developed and implemented in this work that helps to automate and optimize the PEM design process. Power-CAD uses an electrothermal simulation methodology, a parasitic extraction tool, and an optimization algorithm that helps to achieve an optimal layout for a discrete PEM. This approach promises to save time and money for the PEM design industry by significantly reducing the number of design cycles.

A Comparison of Silicon and Silicon Carbide MOSFET Switching Characteristics

Silicon carbide (SiC) is a wide-bandgap semiconductor material that has several promising properties for use in power electronics applications. While SiC manufacturing techniques are still being researched, several SiC devices such as SiC Schottky diodes have entered the market and are finding utility in numerous applications. In this paper, a new 1200 V, 10 A SiC MOSFET will be compared to 1000 V, 10 A Si MOSFET in terms of their dc and transient characteristics and their switching performance in a step-down converter. The SiC device compares favorably to the Si device tested as well as other Si devices available on the market for a similar voltage range.

A wide bandgap silicon carbide (SiC) gate driver for high-temperature and high-voltage applications

Limitations of silicon (Si) based power electronic devices can be overcome with Silicon Carbide (SiC) because of its remarkable material properties. SiC is a wide bandgap semiconductor material with larger bandgap, lower leakage currents, higher breakdown electric field, and higher thermal conductivity, which promotes higher switching frequencies for high power applications, higher temperature operation, and results in higher power density devices relative to Si [1]. The proposed work is focused on design of a SiC gate driver to drive a SiC power MOSFET, on a Cree SiC process, with rise/fall times (less than 100 ns) suitable for 500 kHz to 1 MHz switching frequency applications. A process optimized gate driver topology design which is significantly different from generic Si circuit design is proposed. The ultimate goal of the project is to integrate this gate driver into a Toyota Prius plug-in hybrid electric vehicle (PHEV) charger module. The application of this high frequency charger will result in lighter, smaller, cheaper, and a more efficient power electronics system.

A new approach to designing electronic systems for operation in extreme environments: Part II - The SiGe remote electronics unit

We have presented the architecture, simulation, packaging, and over-temperature and radiation testing of a complex, 16-channel, extreme environment capable, SiGe Remote Electronics Unit containing the Remote Sensor Interface ASIC that can serve a wide variety of space-relevant needs as designed. These include future missions to the Moon and Mars, with the additional potential to operate in other hostile environments, including lunar craters and around the Jovian moon, Europa. We have expanded on the previous introduction of the RSI to show the validity of the chip design and performance over an almost 250 K temperature range, down to 100 K, under 100 krad TID radiation exposure, with SEL immunity and operability in a high-flux SET environment.

A new approach to designing electronic systems for operation in extreme environments: Part I - The SiGe Remote Sensor Interface

We have described the modeling, circuit design, system integration, and measurement of a Remote Sensor Interface (Figure 20) that took place over a span of 5 years and 8 fabrication cycles. It was conceived as part of the Multi-Chip Module (MCM) shown in Figure 21, which also includes a digital control chip for clocking, programming, and read-out. Further work beyond the scope of this was performed to validate the RSI for the extreme environmental conditions of a lunar mission, and individual blocks are presently.

Towards standard component parts in silicon carbide CMOS

A series of “standard” parts for use in extreme environments based on high-temperature silicon carbide complimentary logic is presented. High temperature results and statistical samples are used to demonstrate the maturity of the parts for extreme environment applications.

A high frequency link multiport converter utility interface for renewable energy resources with integrated energy storage

The use of renewable energy resources for bulk energy generation brings a requirement for energy storage systems to support intermittent renewable resources. Energy storage has many uses on the electric grid, and in those capacities renewable energy resources can be combined with energy storage systems. The circuit topologies to connect them with the grid are similar. This paper follows up previous work investigating potential interface topologies and proposes a multiport converter interface with a high-frequency bus which can improve the conversion efficiency from the renewable resource to storage and to the grid by about 3∼4.5% over the separately-connected solution.