Some synchronous, or active, rectifiers provide improved efficiency over diode-bridge rectifiers in part by reducing resistive losses by replacing the diodes with transistors, e.g. metal-oxide-semiconductor field-effect transistors (MOSFETs). The MOSFETs may have a very low on-resistance, e.g. 10 mΩ, compared to a constant junction-voltage drop across the diodes, e.g. about 0.7-1.2 volts.
As the driving loss of the conventional self-driving circuit is very large in wide input voltage range design, continuing research has been undertaken to improve the efficiency of the synchronous rectifier driver circuit. While the efficiency of synchronous rectifiers is significantly greater than diode-bridge rectifiers, power loss of the self-driving clamp MOSFETs imposes a lower limit on the efficiency of conventional self-driving designs. New solutions are needed to further reduce losses in synchronous rectifier driving circuits while doing so with low cost.
USPTO Backgrounds
USPTO Backgrounds