Patent ID: 7215189
Filing Date: 2007-05-08
Classification: H03F,H03K

Abstract:
1. A bootstrap diode emulator circuit for use with a half-bridge switching circuit, the switching circuit including low-side and high-side transistors connected to one another in a totem pole configuration at a load node, the low-side and high-side transistors having respective gate nodes; a driver circuit electrically coupled to the gate nodes of the low-side and high-side transistors, the driver circuit being controllable by at least one control input; a low-side voltage supply to produce a low-side voltage on a low-side supply node; and a bootstrap capacitor coupled between a high-side supply node and the load node, the bootstrap diode emulator circuit comprising: an LDMOS transistor having a gate, a back-gate, a source and a drain, the drain of the LDMOS transistor being coupled to the high-side supply node, the source of the LDMOS transistor being coupled to the low-side supply node; a gate control circuit electrically coupled to the gate of the LDMOS transistor, and a dynamic back-gate biasing circuit electrically coupled to the back-gate of the LDMOS transistor; wherein the gate control circuit is operable to turn on the LDMOS transistor in accordance with the at least one control input and the dynamic back-gate biasing circuit is operable to -dynamically bias the back-gate of the LDMOS transistor when the LDMOS is turned on by applying a voltage to the back-gate of the LDMOS transistor that is close to but slightly lower than a voltage of the drain of the LDMOS transistor.