A power circuit is described that includes a semiconductor body having a common substrate and a Gallium Nitride (GaN) based substrate. The GaN based substrate includes one or more GaN devices adjacent to a front side of the common substrate. The common substrate is electrically coupled to a node of the power circuit. The node of the power circuit is at a particular potential that is equal to, or more negative than, a potential at one or more load terminals of the one or more GaN devices.