A GaN HEMT driver IC with programmable slew rate and monolithic negative gate-drive supply and digital current-mode control

This work presents an intelligent driver IC for 400 V GaN-based Power Factor Correction (PFC) applications. The targeted power level of the converter is 100 W, with a switching frequency above 500 kHz. The IC was implemented in a 140 nm automotive BCD SOI process, while the GaN HEMT and Schottky diode were optimized in a Si-fab compatible GaN-on-Si process. A low-Ron DMOS is integrated in the driver IC to achieve high-speed cascode switching operation. The chip also features a novel dual-mode drive scheme with monolithic negative drive voltage capability and programmable slew rate, as well as a digital peak current-mode controller. Advanced digital PFC control schemes can therefore be implemented, while EMC performance and efficiency can be optimized through active slope control

A dual-mode driver IC with monolithic negative drive-voltage capability and digital current-mode controller for depletion-mode GaN HEMT

\u3cp\u3eThis work presents a driver and controller integrated circuit (IC) for depletion-mode gallium nitride (GaN) high-electron-mobility transistors (HEMTs). The dual-mode driver can be configured for cascode-drive (CD) or HEMT-drive (HD) mode. In the CD mode, a cascode low-voltage DMOS is driven to achieve high-speed normally OFF operation. An active clamping circuit is proposed for the DMOS breakdown protection. In the HD mode, an HEMT gate driver with negative drive-voltage capability and programmable slope control is presented. A digital peak current-mode controller is also integrated with the dual-mode driver. The IC was implemented in a 140-nm automotive bipolar-CMOS-DMOS silicon-on-insulator process. The driver/controller IC is copackaged with an optimized 600-V GaN HEMT fabricated in a GaN-on-Si process. The solution was verified to operate at up to 1 MHz in a 35-W boost converter prototype and achieves a programmable switching-node dv/dt of up to 20 V/ns. To the best of the author's knowledge, this is the first monolithic integration of a cascode MOSFET, device driver, and digital current-mode controller that is designed specifically for high-voltage GaN devices.\u3c/p\u3

Module-level DC/DC conversion for photovoltaic systems

Photovoltaic (PV) systems are increasingly used to generate electrical energy from solar irradiance incident on PV modules. Each PV module is formed by placing a large amount of PV cells, typically 60, in series. The PV system is then formed by placing a number, typically 10–12, of PV modules in series in a string and sometimes by placing multiple strings of series-connected PV modules in parallel, depending on the desired output voltage and power range. In practical cases, differences will exist between output powers of the cells in the various PV modules, e.g. due to (part of) the modules being temporarily shaded, pollution on one or more PV cells, or even spread in cell behaviour. Due to the current-source-type behaviour of PV cells and their series connection these differences will lead to a relatively large drop in PV-system output power. This paper addresses this problem by adding DC/DC converters on PV-module level. The concept, named ‘delta conversion’, aims at averaging out differences in output power between groups of PV cells within modules and between modules inside the PV system. As a result, all these groups of PV cells can output their maximum available power, such that a drop in output power of the total system is prevented. This paper compares the delta-conversion concept with other state-of-the-art module-level power-conversion concepts and presents first measurement results obtained with a demonstrator system