Stepwise data driving method and circuits for low-power TFT-LCDs

The panel AC power, the largest portion of power consumption of data driver circuits in TFT-LCDs, comes from charging and discharging quite large capa citive loads, data lines. The proposed stepwise data driving method can red uce the panel AC power consumption into only a few percent of that of conve ntional ones if the number of step is large enough. In the proposed driving method, external capacitors supply charge to toads in stepwise manner, and the charge returns to the capacitors instead of being discharged to ground . This charge recycling is the basis of reduction of the panel AC power. Th e effect of the proposed driving scheme has been analyzed by HSPICE simulat ion, and more than 75% saving of power consumption has been confirmed by me asurement of the fabricated test circuits with 5-stepwise driving in a 0.6 mum-standard CMOS technology.