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 capacitive loads, data lines. The proposed stepwise data driving method can reduce the panel AC power consumption into only a few percent of that of conventional ones if the number of step is large enough. In the proposed driving method, external capacitors supply charge to loads 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. The effect of the proposed driving scheme has been analyzed by HSPICE simulation, and more than 75% saving of power consumption has been confirmed by measurement of the fabricated test circuits with 5-stepwise driving in a 0.6 μm-standard CMOS technology