A 3.5Â in. QVGA poly-Si TFT-LCD with integrated driver including new 6-bit DAC

By the SOP (system-on-panel) technology with laser crystallization process, all the driver circuits required for 6-bit color QVGA (320 × RGB × 240) LCD are integrated on panel. The integrated data driver comprises a new ramp-driven 6-bit DAC. The characteristics and uniformity of the LTPS (low temperature polycrystalline silicon) has been remarkably enhanced by applying multi-shot ELA (excimer laser annealing) process and surface treatment. The characteristics of the poly-Si TFTs for integration of driver circuits are following: (1) in NMOS, Vth ∼ 1 V and mobility ∼ 240 cm2/V s, (2) in PMOS, Vth ∼ −1.8 V and mobility ∼ 100 cm2/V s.