An a-IGZO TFT-Based AMOLED Pixel Circuit Employing Stable Mobility Compensation Suppressing Degradation of Detected V_TH

Abstract

In this paper, we propose a new active-matrix organic light-emitting diode (AMOLED) pixel circuit using amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs). The proposed pixel circuit consists of seven TFTs and two capacitors, compensating for both threshold voltage (VTH) and mobility variations. The simulation results show that the proposed pixel circuit can successfully compensate for mobility variation. Also, the mobility compensation stage positively affects a significant ${\mathrm{ V}}_{\mathrm{ TH}}$ fluctuation. The proposed circuit is fabricated within an area of $19.95\,\,\boldsymbol{\mu }\text{m}\,\,\times 39.9\,\,\boldsymbol{\mu }\text{m}$ that can achieve 635 pixels per inch (PPI), and the experimental results show relatively consistent current levels even under severe TFT variations.

Keywords

• a-IGZO
• TFT
• pixel circuit
• VTH
• mobility
• compensation