21.3: An Improved Dynamic Ratio Less Shift Register Circuit Suitable for LTPS-TFT LCD Panels

Abstract

We have improved the dynamic ratio less shift register circuit, originally designed for use in Si-LSIs, so as to be applied to LTPS TFTs on the glass substrate with stable operations. In the operation of the dynamic circuit, the conditions arising from two major obstacles, drain avalanche hot carrier effect and massive bias current, which degrade the transistors in the long term operation, can be avoided. By adopting this improved circuit, we are successfully mass-producing highly reliable LTPS-TFT LCD panels which consist only of n-type TFTs.

DC–DC Converters Using Indium Gallium Zinc Oxide Thin Film Transistors for Mobile Display Applications

“…We assumed that the maximum load current of the scan driver for 2.2-in. qVGA display applications is 200 mA when the output voltage of the DC-DC converter remains at 20 V. 10) The supply voltage of driving circuits using low temperature poly-Si (LTPS) TFTs in mobile display applications is generally 5 V, but IGZO TFTs have a relatively low mobility compared with LTPS TFTs. Therefore, we assume that the supply voltage for DC-DC converters using IGZO TFTs is 10 V. the output voltages of the proposed negative DC-DC converter, one-stage Dickson's negative charge pump, and negative cross-coupled DC-DC converter are À5:4, À8:8, and À7:2 V, respectively.…”