Dynamic Characteristic Optimization of 14 a-Si:H TFTs Gate Driver Circuit Using Evolutionary Methodology for Display Panel Manufacturing

Abstract

For thin-film transistor liquid crystal display (TFT-LCD) panel manufacturing, a gate driver circuit with amorphous silicon TFT plays an important role. In this paper, an amorphous silicon gate (ASG) driver circuit is optimized to improve circuit's dynamic characteristics. The adopted simulation-based evolutionary method integrates genetic algorithm and circuit simulator on the unified optimization framework. The circuit consisting of 14 hydrogenated amorphous silicon TFTs (a-Si: H TFTs) used in a large panel is optimized for the given specifications of the rise time < 1.5 mu s, the fall time < 1.5 mu s, and the ripple voltage < 3 V with minimizing the total layout area. By optimizing the width and passive components of the 14 devices, the results of this study successfully meet the desired specifications, where the sensitivity analysis is further conducted to verify the characteristic variation with respect to the optimized parameters. To validate the results, the optimized circuit is fabricated with 4-mu m a-Si: H TFT process, and the experimental result confirms the practicability of achieved design. The ripple voltage within 2.0 V is successfully obtained while the rise and fall times satisfy the required specifications for the fabricated sample. A 35% reduction of the optimized total devices width of a-Si: H TFTs is achieved.