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An analog pulse‐width‐modulation (A‐PWM) Micro‐LED (μLED) pixel circuit based on low‐temperature‐polysilicon (LTPS) thin‐film transistors (TFTs) for mobile displays is proposed. The progressive‐emission mode is implemented using a single Sweep (SW) signal by in‐pixel logic operation circuits. By adjusting the emission time of the progressive‐emission mode, the μLED is biased with the maximum quantum efficiency (EQE). Consequently, the static power consumption of proposed pixels is reduced by 29.2%, compared with conventional schemes. [ABSTRACT FROM AUTHOR]

This paper studies high‐resolution AMOLED displays pixel and driving circuits using 3D stacking LTPS and oxide hybrid TFT integration technology systematically. It is demonstrated the OLED display resolution reaches 1167 PPI when the minimum line width/line spacing is reduced to 1 μm/0.5 μm. In addition, peripheral row and column drive circuits for the high display resolution were also illustrated. Good dynamic performance of the designed driving circuits was obtained thanks to the 3D TFTs. [ABSTRACT FROM AUTHOR]

A pulse‐width‐modulation (PWM) pixel circuit for Micro‐LED display based on low‐temperature poly‐silicon and oxide (LTPO) thin‐film transistor (TFT) is proposed. The PWM falling‐time is reduced to 10 μs, which is only 1/10 of conventional PWM pixel schematics, thanks to the high gain dynamic CMOS inverter for converting data voltage to PWM waveforms and an independent diode‐connected compensation structure for generating constant driving current. The maximum error of PWM conversion and driving current of Micro‐LED is less than 1%, despite VTH shift of oxide TFT ±2 V or VTH variation of LTPS TFT ±1 V. Furthermore, high display resolution above 270 PPI is obtained as the pixel layout reduced to 94 μm×94 μm due to the simplified pixel structure. [ABSTRACT FROM AUTHOR]

This paper presents a PAM and PWM combined Mini‐LED pixel circuit based on oxide TFTs. In the PAM part, a constant current (1mA) allows Mini‐LEDs work at peak efficiency and reduce power consumption. A source follower structure compensates for ΔVTH and VSS IR rise, which has only one TFT on current path, so that the pixel circuit works at low voltage. In the PWM part, a diode connected structure compensates for ΔVTH. Simulation results show that the current error rate is less than 0.81% when ΔVTH of PAM part is within ±3 V. When VSS rises less than 3 V, the current error rate is less than 7.22%. When ΔVTH of PWM part is +3 V, emission time variation is reduced by 99.29% compared with the circuit without compensation. The supply‐voltage can be reduced from 19.7 V to 15 V thanks to the proposed Mini‐LED pixel circuit. [ABSTRACT FROM AUTHOR]

Dynamic X‐ray detecting for large area medical imaging requires high‐gain and stable Active Pixel Sensor (APS) circuit integrated with Thin Film Transistors (TFTs). In this paper, the APS circuit using oxide TFTs is studied based on the small‐signal model, and the charge gain and effects of threshold voltage shift (ΔVth) are investigated. Detailed SPICE simulations show the charge gain of the APS circuit of the oxide TFTs is 234 × of that of the conventional a‐Si:H TFT PPS circuit. [ABSTRACT FROM AUTHOR]

A pulse-width-modulation (PWM) pixel circuit for Micro-LED displays is proposed based on low-temperature poly-silicon and oxide (LTPO) thin-film transistors (TFTs). The pixel circuit features fast PWM transition, as the PWM falling-time is less than 20 μs thanks to the high-gain dynamic inverter. Furthermore, the proposed pixel circuit can compensate the degradation and non- uniformities of TFT characteristics of LTPO TFTs through auto- zeroing configuration of the dynamic inverter and a diode- connected threshold voltage compensation structure. The error rate of luminous time is less than 3.2% and the error rate of current is less than 1% under VTH shift of oxide TFT ±2 V or LTPS TFT ±1 V. [ABSTRACT FROM AUTHOR]

A concise pixel circuit with interleaved Emit signals is proposed for active matrix organic light‐emitting diode (AMOLED) displays, on the basis of low‐temperature polycrystalline silicon oxide (LTPO) TFTs. The oxide TFT can be re‐used for both initialization and threshold voltage extraction periods, using interleaved Emit signals of adjacent lines with overlapped waveforms. The proposed pixel circuit consists of 1 oxide TFT and 5 p‐type LTPS TFTs, while only 2~3 types of line‐by‐line scanning driving signals, i.e. the Emit signal and the Scan signal, are required. Implementation of the proposed pixel circuit shows that the occupation can be reduced to 40 μm × 56.7 μm. Furthermore, optimization of the pixel circuit shows the emission current error is less than 2.3% with threshold voltage variation of ± 0.5 V, while refresh rate from 1 to 120 Hz can achieved. [ABSTRACT FROM AUTHOR]

An OLEDoS microdisplay system is proposed in this paper, which includes a voltage‐driving pixel circuit, an OLED threshold voltage detection method, and a fast‐progressive compensation scheme. The measurement result shows that the range of the programming display voltage of the proposed voltage‐driving pixel circuit is 5.15 times larger than the gate‐source voltage difference of the driving transistor. The measured lowest current of a pixel can be as low as 2.89 pA. [ABSTRACT FROM AUTHOR]

In this work, we proposed a voltage‐programmed AMOLED pixel circuit using amorphous InGaZnO thin‐film transistors (a‐IGZO TFTs). For every display frame, thanks to the capacitive coupling method, the gate‐source voltage of the driving transistor is programmed through a zero to a positive value process, i.e. a unipolar sweeping direction is maintained for the driving transistor, to suppress the electrical hysteresis effects. In addition, the threshold voltage variation of the driving transistor can also be compensated through a source follower structure. Simulation results indicate that the relative current error is less than 30% for threshold voltage variations of ± 0.4 V. [ABSTRACT FROM AUTHOR]

A new pixel circuit is proposed for the realization of high resolution and high uniformity organic light-emitting diode on silicon (OLEDoS) microdisplays in this article. A compensation scheme is adopted to mitigate the influence of threshold voltage variation of the driving transistor on display uniformity. Furthermore, two coupling capacitors are used to reduce the voltage at the gate terminal of the driving transistor in order to extend the data voltage range. The performance of the proposed pixel circuit is verified in an industrial 0.18- $\mu \text{m}$ CMOS process. Simulation results show that the data voltage of the proposed pixel circuit ranges from 0.5 to 3.12 V, which is up to $4.37\times $ wider than the previously published pixel circuits. The emission current error of the proposed pixel circuit varies from −2.1% to 2.08%, under the condition of ±5 mV threshold voltage variation for the driving transistor. The maximum emission current error changes from −10.36% to −2.62% when the OLED turn-on voltage is increased by 5 to 20 mV due to device aging. Furthermore, the proposed pixel circuit only occupies a layout area of $8.1\,\,\mu \text{m}\,\,\times {4}\,\,\mu \text{m}$. [ABSTRACT FROM AUTHOR]

This work presents a peripheral compensation scheme for AMOLED displays, in which threshold voltage and aging information of driving TFT, and the signal data voltage are analogously added in the pixel circuits without changing the gamma corrections and increasing the bit and voltage range of DAC. Without increasing the resolution and voltage range of DAC, the cost and power consumption are reduced. A driving scheme using current sensing method with adjustable settling time and peripheral compensation system are also proposed. [ABSTRACT FROM AUTHOR]

A current comparison scheme for external compensation circuit of AMOLED displays is proposed. In this scheme, a current comparator is designed to sense the difference between the reference current and the driving current of pixels and to output a corresponding digital signal to the compensation block. For the current comparator, a sense amplifier is used to amplify the current difference, which can effectively increase the accuracy of the current comparator. Simulation results show that the accuracy of the proposed current comparator is 1nA and the sensing error is lower than 0.224 %, when the reference current is 500 nA. [ABSTRACT FROM AUTHOR]

Using low-temperature poly-silicon thin-film transistors (LTPS TFTs) as a basis, a pixel circuit for an active matrix organic light-emitting diode (AMOLED) with narrow bezel displays was developed. The pixel circuit features mono-type scanning signals, elimination of static power lines, and pixel-integrated emitting control functions. Therefore, gate driver circuits of the display bezel can be simplified efficiently. In addition, the pixel circuit has a high-resolution design due to an increase of the pulse width of the scan signal to extend the threshold voltage and internal–resistance drop (IR drop) detection period. Further, regarding the influences of process–voltage–temperature (PVT) variation in the pixel circuit, comparison investigations were carried out with the proposed circuit and other pixel circuits with mono-type scanning signals using Monte Carlo analysis. The feasibility of the proposed pixel circuit is well demonstrated, as the current variations can be reduced to 2.1% for the supplied power reduced from 5 V to 3 V due to IR drop, and the current variation is as low as 10.6% with operating temperatures from –40 degrees to 85 degrees. [ABSTRACT FROM AUTHOR]