3.2: An Integrated Gate Driver Circuit Employing Depletion‐Mode IGZO TFTs

Abstract

Integrated gate driver circuit with Oxide TFTs often suffers from the leakage current problem due to the depletion-mode TFT's characteristic. This paper analyzed the origin of circuit failure and proposed a leakage current cutting technique in which using output feedback to turn off the normally-on switches. The feedback scheme is designed not only within its own stage but across the neighboring stages. Compared with previous work, it avoids the degradation of the output caused by the feedback TFT, thus providing a more robust solution. The circuit is fabricated employing a-IGZO TFTs. The experiment result shows that the circuit works successfully with maximum -4.5V threshould voltage.

24.1: Invited Paper: Development of 55 inch 4K AMOLED TV by Inkjet Printing Process

“…The oxide TFT backplane is fabricated based on full Gen 8.5 glass. The etch stop layer (ESL) type oxide TFT with bottom gate and top contact of source drain is adopted due to its good uniformity and low cost [4]. And for large size panel driving, in order to guarantee the charging speed, the gate or data line's resistance should be as small as possible, thus copper and very thick Al process are preferable.…”

20.1: Flexible AMOLED Display and Gate‐driver with Self‐aligned IGZO TFT on Plastic Foil

“…Next, a 160-stage gate-driver has been designed and measured. It comprises only 10 TFT per stage [3], employing in total 1600 TFT. This allows us to achieve a very dense layout, requiring only 125μm width per stage.…”

“…On the other side medium and large sized displays where only medium resolution is required but cost is the dominating issue. There are several domains where cost needs to be addressed, OLED deposition where we can see a strong push for printed OLEDs for large size displays [1], cost reduction in the backplane by switching to metaloxide TFT and reducing the number of mask steps [2] and finally integrating the line driver into the backplane process [3]. More value can be added by moving to flexible displays, allowing additional form factor, lighter weight and mechanical robustness.…”

P‐26: A Low‐Power Gate Driver Using Depletion‐Mode a‐IGZO TFTs

“…In order to solve the problem of leakage current, several gate drivers composed of a-IGZO TFTs were proposed [8]- [10]. As an additional low-voltage-level power source is employed in the circuit design, the depletion-mode TFTs can be turned off by applying a negative V GS [8], [9]. Therefore, the gate drivers can be operated successfully based on depletion-mode a-IGZO TFTs.…”

“…Therefore, the gate drivers can be operated successfully based on depletion-mode a-IGZO TFTs. Nevertheless, some TFTs still turned off with a zero VGS in each stage of their gate drivers [8], [9]. Although the correctness of the circuit operation is not affected by the leakage current through these TFTs, the large power dissipation should be concerned.…”