High voltage composite semiconductor device with protection for a low voltage device

摘要

There are disclosed herein various implementations of composite semiconductor devices including a voltage protected device. In one exemplary implementation, a normally OFF composite semiconductor device comprises a normally ON III-nitride power transistor (310) having a first output capacitance (C1)(318), and a low voltage (LV) device (320) cascoded with the normally ON III-nitride power transistor to form the normally OFF composite semiconductor device (300), the LV device having a second output capacitance (C2)(348). A ratio of the first output capacitance to the second output capacitance is set based on a ratio of a drain voltage of the normally ON III-nitride power transistor to a breakdown voltage of the LV device so as to provide voltage protection for the LV device.