An isolated gate driver is a key component for electric and hybrid-electric vehicles, allowing the MCU to control the inverter effectively and efficiently. The bias supply for the isolated gate driver must be simple and robust, with low EMI. In this presentation, two different types of isolated bias supply for isolated gate drivers are introduced: the open-loop LLC-converter solution and the integrated-transformer solution. The presentation provides guidelines for designing isolated bias supplies — and also introduces different ways of creating isolated bias supply, comparing different solutions based on control strategy, transformer construction and EMI performance.