A low-ripple charge pump with continuous pumping current control

This paper presents a low-ripple regulated charge pump with continuous pumping current control. Output voltage is continuously regulated for full-range load variation. Multi-phase charge pump can be easily achieved under the constant pumping frequency control scheme. In this way, the output voltage ripple can be minimized further. An experimental chip has been fabricated in a 0.5μm CMOS process and the active area is 0.3mm
²
. The measured ripple voltage is less than 28mV at 20mA load current with 100 kHz pumping frequency. The implemented chip is designed for portable TFT-LCD drivers. It delivers a regulated voltage from 4.5V to 5V with 1μF flying and load capacitors