## Abstract

An eight FETs and two capacitors (8T2Cs) pixel circuit with dual data voltages (<inline-formula> <tex-math notation="LaTeX">$V_{\text{data}}$</tex-math> </inline-formula>’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 (<inline-formula> <tex-math notation="LaTeX">$V_{\text{th}}$</tex-math> </inline-formula>)-compensated gray levels. It is known that conventional displays are 1024 gray levels by inputting 10-bit <inline-formula> <tex-math notation="LaTeX">$V_{\text{data}}$</tex-math> </inline-formula>’s to the pixel circuit for generating pixel currents (<inline-formula> <tex-math notation="LaTeX">$I_{\text{pixel}}$</tex-math> </inline-formula>’s), resulting in the <inline-formula> <tex-math notation="LaTeX">$V_{\text{data}}$</tex-math> </inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">$V_{\text{data}}$</tex-math> </inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">$V_{\text{data}}$</tex-math> </inline-formula>’s to generate the required <inline-formula> <tex-math notation="LaTeX">$I_{\text{pixel}}$</tex-math> </inline-formula>’s for 10-bit gray levels with the dynamic range of <inline-formula> <tex-math notation="LaTeX">$V_{\text{data}}$</tex-math> </inline-formula> reduced to 0.64 V, while the <inline-formula> <tex-math notation="LaTeX">$V_{\text{th}}$</tex-math> </inline-formula>’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 <inline-formula> <tex-math notation="LaTeX">$V_{\text{th}}$</tex-math> </inline-formula>’s compensated, the <inline-formula> <tex-math notation="LaTeX">$\Delta I_{\mathbf{pixel}}$</tex-math> </inline-formula>’s with respect to the currents at corner TT are improved from the averaged <inline-formula> <tex-math notation="LaTeX">$+$</tex-math> </inline-formula>285% of FF to <inline-formula> <tex-math notation="LaTeX">$+$</tex-math> </inline-formula>11.1% and the averaged <inline-formula> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula>69.1% of SS to <inline-formula> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula>9.1%. Favorable voltage linearities were also seen between gray levels. Both DNLs and INLs in the range of <inline-formula> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula>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.

Original language | English |
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Pages (from-to) | 1-12 |

Number of pages | 12 |

Journal | IEEE Journal of Solid-State Circuits |

DOIs | |

State | Accepted/In press - 2024 |

## Keywords

- <inline-formula xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <tex-math notation="LaTeX">$V_{\text{data}}$</tex-math> </inline-formula> range
- <inline-formula xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <tex-math notation="LaTeX">$V_{\text{th}}$</tex-math> </inline-formula> compensation
- AMOLED
- CMOS
- Current density
- dual data voltages
- Field effect transistors
- high pixel-per-inch (PPI)
- Hyperspectral imaging
- Indexes
- Mathematical models
- micro-organic light-emitting diode (OLED)
- microdisplays
- Organic light emitting diodes
- pixel circuit
- Threshold voltage