M. A. Huque

A 200 °C Universal Gate Driver Integrated Circuit for Extreme Environment Applications

High-temperature power converters (dc-dc, dc-ac, etc.) have enormous potential in extreme environment applications, including automotive, aerospace, geothermal, nuclear, and well logging. For successful realization of such high-temperature power conversion modules, the associated control electronics also need to perform at high temperature. This paper presents a silicon-on-insulator (SOI) based high-temperature gate driver integrated circuit (IC) incorporating an on-chip low-power temperature sensor and demonstrating an improved peak output current drive over our previously reported work. This driver IC has been primarily designed for automotive applications, where the underhood temperature can reach 200 °C. This new gate driver prototype has been designed and implemented in a 0.8 μm, 2-poly, and 3-metal bipolar CMOS-DMOS (Double-Diffused Metal-Oxide Semiconductor) on SOI process and has been successfully tested for up to 200 °C ambient temperature driving a SiC MOSFET and a SiC normally-ON JFET. The salient feature of the proposed universal gate driver is its ability to drive power switches over a wide range of gate turn-ON voltages such as MOSFET (0 to 20 V), normally-OFF JFET (-7 to 3 V), and normally-ON JFET (-20 to 0 V). The measured peak output current capability of the driver is around 5 A and is thus capable of driving several power switches connected in parallel. An ultralow-power on-chip temperature supervisory circuit has also been integrated into the die to safeguard the driver circuit against excessive die temperature (≥220 °C). This approach utilizes increased diode leakage current at higher temperature to monitor the die temperature. The power consumption of the proposed temperature sensor circuit is below 10 μW for operating temperature up to 200 °C.

A low power sensor signal processing circuit for implantable biosensor applications

A low power sensor read-out circuit has been implemented in 0.35 µm CMOS technology that consumes only 400 µW of power and occupies an area of 0.66 mm2. The circuit is capable of converting the current signal from any generic biosensor into an amplitude shift keying (ASK) signal. The on-chip potentiostat biases the chemical sensor electrodes to create the sensor current which is then integrated and buffered to generate a square wave with a frequency proportional to the sensor current level. A programmable frequency divider is incorporated to fix the ASK envelope frequency to be inbetween 20 Hz and 20 kHz, which is within the audible range of human hearing. The entire transmitter block operates with a supply voltage as low as 1.5 V, and it can be easily powered up by an external RF source. Test results emulate the simulation results with good agreement and corroborate the efficacy of the designed system.

An SOI-based High-Voltage, High-Temperature Gate-Driver for SiC FET

A high-voltage and high-temperature gate-driver chip for SiC FET switches is designed and fabricated using 0.8- micron, 2-poly and 3-metal BCD on SOI process. It can generate output voltage swing from -5 V to 30 V and can operate up to 175degC ambient temperature. This gate-driver chip is intended to drive SiC power FETs in DC-DC converters in a hybrid electric vehicle. The converter modules along with the gate-driver chip will be placed very close to the engine where the temperature can reach up to 175degC. Successful operation of the chip at this temperature without heat sink and liquid cooling will help to achieve greater power-to-volume as well as power-to-weight ratios for the power electronics module. Initial test results presented in this paper also validate the simulation.

SOI-based integrated circuits for high-temperature power electronics applications

The growing demand for hybrid electric vehicles (HEVs) has increased the need for high-temperature electronics that can operate at the extreme temperatures that exist under the hood. This paper presents a high-voltage, high-temperature SOI-based gate driver for SiC FET switches. The gate driver is designed and implemented on a 0.8-micron BCD on SOI process. This gate driver chip is intended to drive SiC power FETs for DC-DC converters and traction drives in HEVs. To this end, the gate driver IC has been successfully tested up to 200ºC. Successful operation of the circuit at this temperature with minimal or no heat sink, and without liquid cooling, will help to achieve higher power-to-volume as well as power-to-weight ratios for the power electronics modules in HEVs.

Silicon-on-insulator based high-temperature electronics for automotive applications

In recent years increasing demand for hybrid electric vehicle has generated the need for reliable and low-cost high-temperature electronics which can operate at the extreme temperatures that exists under the hood. A high-voltage and high-temperature gate-driver integrated circuit for SiC FET switches is designed and implemented in a 0.8-micron Silicon-on-Insulator high-voltage process. First prototype chip has been successfully tested up to 200degC ambient temperature without any heat sink or cooling mechanism. This gate-driver chip is intended to drive SiC power FETs of the DC-DC converters in a hybrid electric vehicle. The converter modules along with the gate-driver chip will be placed very close to the engine where the temperature can reach up to 175degC. Successful operation of the chip at this temperature with or without minimal heat sink and without liquid cooling will help achieve greater power-to-volume as well as power-to-weight ratios for the power electronics module. A second prototype has also been designed with more robust features.

A Low Power, Low Voltage Current Read-Out Circuit for Implantable Electro-Chemical Sensors

A low power, low voltage current read-out circuit suitable for implantable electro-chemical sensors has been designed, fabricated and tested. The circuit converts a very low level current signal from a generic sensor into an ASK signal where the modulating signal frequency is proportional to the sensor output current, usually in the range of 0.2 muA to 2 muA. An on-chip potentiostat is also incorporated in the design to bias the sensor electrodes. A programmable frequency divider is integrated into the chip to set the ASK envelope frequency within the audio frequency range for ease of testing. This chip can operate with a supply voltage as low as 1.5 V and consumes only about 400 muW power. A second generation of the chip has been designed with FSK modulation scheme. FSK modulated signals offer better noise performance and higher power efficiency compare to ASK modulated signals.

A UNIVERSAL SOI-BASED HIGH TEMPERATURE GATE DRIVER INTEGRATED CIRCUIT FOR SiC POWER SWITCHES WITH ON-CHIP SHORT CIRCUIT PROTECTION

In recent years, increasing demand for hybrid electric vehicles (HEVs) has generated the need for reliable and low-cost high-temperature electronics which can operate at the high temperatures under the hood of these vehicles. A high-voltage and high temperature gate-driver integrated circuit for SiC FET switches with short circuit protection has been designed and implemented in a 0.8-micron silicon-on-insulator (SOI) high-voltage process. The prototype chip has been successfully tested up to 200°C ambient temperature without any heat sink or cooling mechanism. This gate-driver chip can drive SiC power FETs of the DC-DC converters in a HEV, and future chip modifications will allow it to drive the SiC power FETs of the traction drive inverter. The converter modules along with the gate-driver chip will be placed very close to the engine where the temperature can reach up to 175ΰC. Successful operation of the chip at this temperature with or without minimal heat sink and without liquid cooling will help achieve greater power-to-volume as well as power-to-weight ratios for the power electronics module.

High temperature performance measurement and analysis of GaN HEMTs

Objective of this paper is to evaluate the performance of GaN HEMTs for high temperature applications. A sample AlGaN/GaN HEMT structure is investigated using empirical data to evaluate the device performance at high temperatures. Input transfer and output characteristics are the key focus along with transconductance and saturation current. Intrinsic device parameters were calculated using measured S-parameter data at various frequencies under different bias conditions and temperatures. Transconductance found at 398 °K is 2.5 mS for the entire gate width. DC characteristics of the fabricated devices were examined at temperatures ranging from 295 °K to 363 °K. Maximum drain current measured at room temperature was 214 mA which reduced to 192 mA at 363 °K. Reduction in saturation drain current is found due to decrease in saturation carrier velocity and two dimensional electron density. Structure based simulation tool ATLAS from Silvaco Int. is used for numerical simulations. The simulated device performance is in good agreement with the empirical results. Experimental results for the critical parameters suggest that the device can operate in the GHz Range for temperature up to 600 °K. Further enhancement of the model device is suggested upon reviewing the measured results to improve the high-temperature performance.

AN EFFICIENT NUMERICAL METHOD OF DC MODELING FOR POWER MOSFET, MESFET AND AlGaN/GaN HEMT

In this paper, an efficient numerical model applicable for wide varieties of long channel field-effect transistors (MOSFET, MESFET, HEMT, etc.) is developed. A set of available data is used to calculate the model parameters and another set of data is used to verify the accuracy of the model. This model provides a single expression that is applicable for the entire range of device biasing and can predict the output parameters with less than 1% error compared to the experimental results. Lagrange polynomial, the highest degree of polynomial for any given set of data, is used to derive the model from available data. This method is efficient in the sense that it can be derived from a limited number of experimental data and since it uses only one equation for entire range of the device operation hence its computational cost is also small.

Effect of the aspect ratio in AlGaN/GaN HEMT’s DC and small signal parameters

In this work the effects of the aspect ratio (gate width/ channel length, W/L) in DC and small signal parameters of AlGaN/GaN HEMTs are studied. An analytical model has been developed for theoretical calculation of the device DC performance at different aspect ratios. Experimental results of the fabricated AlGaN/GaN HEMT devices are used to validate the analytical model. Numerical simulations are performed to observe the effects of the aspect ratio on gate capacitance, transconductance and unity gain cut-off frequency.