Novel Low-Side/High-Side Gate Drive and Supply With Minimum Footprint, High Power Density, and Low Cost for Silicon and Wide-Bandgap Transistors

Abstract

High-power silicon field-effect transistors as well as insulated gate bipolar transistors and particularly wide-bandgap semiconductor transistors typically need negative turn-off voltage for a secure off-state, resilience to spurious turn on, and rapid transition through the saturation mode. We present a gate driver configuration with compact and very efficient supply of the high and low sides of power transistor bridges with asymmetric bipolar control voltages without the need for costly and lossy isolated dc-dc converter and only low-voltage active components. The underlying negative voltage gate driver supply circuit consists of only a few cost-efficient components, its electrical potential is referenced to the source of the controlled semiconductor power switch, and its operation is synchronized with the gate driver output. It outcompetes the established use of isolated dc-dc converters in gate circuits with negative voltage needs with respect to cost, size, reliability, and efficiency. Importantly, the proposed negative voltage supply allows bootstrapping without the need for controllable high-voltage semiconductors for the sake of further cost reduction. We present detailed design rules of the circuit and experimentally validate circuit and control. In the automotive prototype implementation, size of the gate driver supply was reduced by 61%, cost by 57%, and loss by more than 16%.