Reverse capacitor voltage balancing for high current high voltage charge pump circuits

Abstract

A switched capacitor converter includes a primary switching circuit, a flying capacitor circuit, and a secondary switching circuit. The primary switching circuit includes plurality of switching transistors in series. The flying capacitor circuit includes one or more flying capacitors with each flying capacitor connected to a switching transistor. The secondary switching circuit includes two or more switching transistors and provides a first path for charging and a second path for discharging the flying capacitors. At startup, the flying capacitors are discharged via a first current source while the switching transistors are turned off. After discharging, the flying capacitors are charged via a second current source, while a first switching transistor of the primary switching circuit is kept turned off and the rest of the switching transistors perform switching according to a switching cycle. After charging, the switched capacitor converter may enter a steady state operation.