An Ultra-High 6318-PPI Pixel Circuit for Micro-OLED Displays With Vth Compensated up to 10-bit Gray Levels

Shih Song Cheng, Paul C.P. Chao*

*此作品的通信作者

研究成果: Article同行評審

摘要

An eight FETs and two capacitors (8T2Cs) pixel circuit with dual data voltages (Vdata 's) is proposed for micro-organic light-emitting diode (OLED) displays, resulting in and validated successfully with an ultra-high pixel-per-inch (PPI) of 6318. This designed pixel circuit can also realize 10-bit threshold voltage (Vth)-compensated gray levels. It is known that conventional displays are 1024 gray levels by inputting 10-bit V data 's to the pixel circuit for generating pixel currents (I pixel's), resulting in the V data range of at least 5.12 V with the DAC's 1-LSB of 5 mV assumed. However, for the CMOS processes of dozens of nanometers, only high-voltage FETs (HVFETs) in large sizes can drive with such large V data range, undermining the chance of high PPI. The new pixel circuit proposes herein low-voltage FETs (LVFETs) in place of most HVFETs successfully by synthesizing two V data 's to generate the required I pixel 's for 10-bit gray levels with the dynamic range of V data reduced to 0.64 V, while the V th 's can still compensate. This circuit featuring 6318 PPI is successfully fabricated in the chips of the 55-nm CMOS process for validations. The simulation result show that, with Vth's compensated, the Δ Ipixel's with respect to the currents at corner TT are improved from the averaged +285% of FF to +11.1% and the averaged -69.1% of SS to -9.1%. Favorable voltage linearities were also seen between gray levels. Both DNLs and INLs in the range of ±1 LSB were measured on a testkey-form circuit, appearing consistency with the simulation results and verifying the expected performance of the designed dual-data-driven pixel circuit.

原文English
頁(從 - 到)2236-2247
頁數12
期刊IEEE Journal of Solid-State Circuits
59
發行號7
DOIs
出版狀態Published - 1 7月 2024

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