Design of analog pixel memory for low power application in TFT-LCDs

Two types of analog memory cells realized in a 3-μm low temperature polycrystalline silicon (LTPS) technology are proposed to achieve low power application for thin film transistor liquid crystal displays (TFT-LCDs). By employing the inversion signal in the storage capacitor with complementary source follower, the frame rate to refresh the static image can be reduced from 60 to 3.16 Hz with the output decay less than 0.1 V under the input data from 1 to 4 V. To further diminish threshold voltage drop from source follower structure, a compensation technique is implemented to the proposed analog memory cells. In addition, asymmetric output voltage can be also minimized by adding a reference voltage to achieve symmetric output waveform.