A Hybrid Cockcroft-Walton/Dickson Multiplier for High Voltage Generation

This paper presents a voltage multiplier topology that is a hybrid between a Cockcroft-Walton multiplier and a Dickson charge pump. The Cockcroft-Walton structure exhibits significant output voltage drop under load as the number of multiplier stage increases. This is because all coupling capacitors are connected in series. Dickson charge pump mitigates this issue by connecting all capacitors in parallel. But this solution comes at the expense of large capacitor voltage stress at the last multiplier stage. The proposed hybrid structure arranges some capacitors in parallel and others in series, thereby achieving low output voltage drop and low capacitor voltage stress at the same time. We develop a model that predicts hybrid multipliers performance and validates it experimentally. We also demonstrate a 60-2.25kV dc-dc converter based on a 16-stage hybrid voltage multiplier which achieves a voltage gain of 12.8 while keeping the highest capacitor voltage stress to 660V.