An On-Chip Cockcroft-Walton Switched-Capacitor Converter Using Split-Phase Control for Improved Soft-Charging with 9.72 Conversion Gain

Abstract

This work proposes a switched-capacitor (SC) converter for high voltage generation required for medical ultrasound imaging system. The SC converter is quite advantageous for the implementation of an integrated circuit (IC) in terms of area. Besides, the SC converter has relatively less conduction loss than an inductive DC-DC boost converter. For these reasons, the SC converter is suitable for generating high voltages in ICs. However, the power loss of the SC converter can be analyzed by dividing it into three major losses. This work analyzes these losses and applies techniques to reduce them in order to improve the conversion gain and power efficiency. As a result, an on-chip Cockcroft-Walton SC converter using split-phase control for improved soft-charging with conversion gain 9.72 and power efficiency 70.1% suitable for the portable ultrasound imaging device is implemented. However, the measurement results of this study were worse than the simulation results due to mismatched control clock.