Integrated Low-Voltage Floating Power Supply in High-Voltage Technology for High $dV/dt$ Applications

This letter presents an integrated low-voltage floating supply in monolithic high-voltage technology aimed at supplying signal processing circuits, used in insulated-gate bipolar transistor or MOSFET-based inverter applications, diffused inside the same floating pocket where the power supply resides. This pocket is biased by the supply output with a voltage lower than the bootstrap capacitor voltage. As a consequence, signal processing circuits can be implemented using high performance, 5 V MOSFETs instead of the 20 V devices that are necessary when the bootstrap capacitor is used as a power supply. Measurements performed on a first test chip demonstrated the feasibility of the idea. The circuit was modified to make it insensitive to the charge injection phenomena caused by high $dV/dt$ typical of these applications, as confirmed by measurements on a second test chip.