Patent ID: 8773091

Claim:
An apparatus comprising: a switching circuit that includes a switching node having a switch node voltage and that receives an input voltage; an inductor that is coupled to the switching node; a capacitor that is coupled to the inductor; and a controller that is coupled to the switching circuit and that operates at a switching frequency with a conversion efficiency, wherein the controller controls slewing of the switching node voltage using a negative inductor current from the inductor, and wherein, for the conversion efficiency, the switching frequency and the input voltage are sufficiently large so as to overcome a loss incurred by using the negative inductor current; wherein the switching circuit further comprises high-side transistor that receives the input voltage at is drain, that is coupled to the switching node at its source, and that is coupled to the controller at its gate; wherein the switching circuit further comprises a depletion mode diode having: a depletion mode transistor that is coupled to the switching node at its drain and ground at its gate; a diode that is coupled between the source of the depletion mode transistor and ground; and a variable capacitor that is coupled between the source of the depletion mode transistor and ground.