A capacitive level shifter for high voltage (2.5kV)

A capacitive level-shifter as a part of a high voltage halfbridge gate driver is presented in this work. The level-shifter utilizes a differential capacitor pair to transfer the information from low side to high side. A thorough evaluation of the critical parts of the level-shifter is presented with focus on low power consumption as well as low capacitive load between the floating half-bridge node and ground (output capacitance). The operation of the level-shifter is tested and verified by measurements on a prototype half-bridge gate driver. Results conclude stabile operation at 2.44kV, 50kHz with a current consumption of 0.5mA. Operation voltage was limited by test equipment. The output capacitance is 4pF@1.5kV.