A low-ripple poly-Si TFT charge pump for driver-integrated LCD panel

A low-ripple charge pump for voltage up-conversion is described which was implemented in a poly-Si thin-film-transistor (TFT) technology for driver-integrated liquid-crystal-display (LCD) panels. The ripple voltage of the charge pump is reduced by employing a multi-phase clocking method. The charge pump was implemented in a poly-Si TFT technology. For output current of 100/spl mu/A, filtering capacitor of 100 pF and pumping clock frequency of 1 MHz, the measured ripple voltage of the proposed charge pump is 135 mV while that of conventional Dickson charge pump is 590 mV. The measured pumping efficiencies of the Dickson and proposed 4-phase clocking charge pump are 59% and 65%, respectively.