Display Driver Research Articles

Near‐field communication integration into in‐cell touch thin‐film‐transistor liquid‐crystal display

AbstractIn this paper, we demonstrated the front NFC card swipe and touch display in Touch and Display Driver Integration (TDDI) liquid crystal display (LCD) through the technologies shown later. A new NFC sampling and noise reduction algorithm was used to reduce the generation of the ghost position and touch failure. The touch/NFC part‐time driving was applied to optimize the noise interference when NFC works. Meanwhile, we integrated the NFC antenna in the TDDI LCD and added a new display signal filter circuit and VCOM driver signal. In the NFC in‐cell demo, front NFC swiping distance of 60 mm is achieved.

An OLED display driver IC with high‐gain fast‐slew circuit and on‐the‐fly self‐repair technique for high‐resolution display

AbstractThis paper presents an OLED display driver IC with high‐gain fast‐slew (HGFS) and on‐the‐fly self‐repair (OFSR) circuits for a spatial resolution of WQHD and a frame rate of 120 Hz. The proposed HGFS circuit increases the slewing current of the unity‐gain amplifier of the source driver when the input voltage is largely changed, reducing the settling time of the source driver as the resolution and frame rate increase. To enhance image quality by correcting line defects, the OFSR circuit replaces a faulty channel with a spare dummy channel. The OLED display driver IC was manufactured using a 28‐nm high‐voltage process with 8 V/20 V transistors and has 2880 source drivers for WQHD display. The measurement results indicate a horizontal line time of 2.7 μs with a slew rate of 7.675 V/μs, supporting WQHD resolution and 120‐Hz frame rate. The displayed image demonstrates that the vertical line defect has disappeared with the use of OFSR.

High Performance Amorphous IGO Thin Film Transistors Grown at Low Temperature

Polycrystalline indium gallium oxide has been widely studied in the domain of oxide thin film transistors (TFTs) due to its high mobility. However, there are few researches focus on amorphous IGO (a‐IGO), which has the advantage of large area display. Herein, high‐performance a‐IGO TFTs are demonstrated by magnetron sputtering method with simple process. The efficiency of a‐IGO TFTs fabricated under various conditions are evaluated, and a‐IGO TFTs prepared by 27 nm thin films grown at 220 °C have the best electrical properties. It exhibits the mobility of 35 cm2 V−1 s−1, threshold voltage of 0.5 V, subthreshold swing of 0.8 V dec−1, and the on/off current ratio over 106. This is due to the precise control of the deposition energy state by temperature during sputtering and the influence of the semiconductor layer thickness on the distribution of the accumulation layer. The results present here demonstrate a simple fabrication method for high‐performance amorphous oxide TFT, providing a new option for display driver circuits.

OLED Microdisplay With Monolithically Integrated CAAC-OS FET and Si CMOS Achieved by Two-Dimensionally Arranged Silicon Display Drivers

OLED Microdisplay With Monolithically Integrated CAAC-OS FET and Si CMOS Achieved by Two-Dimensionally Arranged Silicon Display Drivers

Adaptive micro-projection system based on liquid lens

Projectors play an important role in the fields of education, entertainment, etc. The conventional projectors are generally bulky, lack of portability and adaptability. In this paper, an adaptive micro-projection system based on liquid lens is proposed. The main part of the system consists of a sequential three-color light source module, a light-homogenized module, a piece of liquid–crystal-on-silicon (LCoS) with high refresh rate, a polarization beam splitter (PBS), a zoom projection lens based on liquid lenses, a liquid lens controller and a display driver board. By adjusting the driving voltages on the liquid lenses, the adaptive micro-projection system can work with the distance at least from 150 mm to 310 mm continuously. Moreover, by synchronously controlling the refresh of the LCoS and the sequential lighting of the three-color light source through the display driver board, a 60 Hz color video display can be realized with only one piece of LCoS. We introduce the design method of the liquid lens based zoom projection lens in detail and provide an optical structure of the liquid lens based zoom projection lens with excellent performance. The control software and hardware of the system are carefully developed. Simulations and experiments demonstrate the feasibility of the system. The proposed system has the characteristics of fast response, portability, integration and high adaptability and is expected to be used in virtual reality (VR), augmented reality (AR), on-board display, head-mounted display and so on.

Poster Session: Threshold versus intensity curves measured with a new high-brightness display system.

Classical threshold vs. intensity (tvi) curves were measured using optical systems and were generally limited to increment test stimuli and relatively simple spatial patterns. Modern displays provide more flexibility in terms of stimuli spatial profiles but are usually dim enough that there may be rod intrusion when measuring cone responses. Here we describe a high-brightness display system and present tvi's for increment and decrement achromatic tests. The system consists of a PROPixx three-chip DLP LED color projector (VPixx Technologies, Saint-Bruno, Canada) controlled via a Datapixx display driver, with 12-bit digital to analog conversion per RGB channel. Light from the projector is collected in a large diameter lens and focused on high gain rear projection screen. Retinal illuminance of the background may be varied in three ways: (a) varying the mean current supplied to the LEDs from the controller (adjustable in software); (b) using calibrated neutral density filters mounted near the eye; and (c) changing the midpoint of the RGB channels in software (e.g., making the white background as R=G=B=0.1 instead of 0.5). Method (c) is made easier by the fact that the PROPixx "gamma curve" is linear, which also means that no RGB bits are lost to gamma correction. We will show thresholds for achromatic tests on a white background varying from 0.56 to 4.03 log trolands, with preliminary results suggesting differences in the tvi curves between the increment and decrement tests.

4‐4: High PPI MicroLED display driver circuit and device structure

This paper proposes a new type of display driver circuit and TFT device structure, studies the brightness control technology of high PPI Micro LED display, uses the inverter PWM driver module loaded in the traditional internal compensation driver circuit, when the low gray scale display, By triggering PWM module, the PWM is used to further divide the low gray scale under PAM mode again, so as to increase the gray level. Meanwhile, the introduction of Micro LED reverse NMOS and PMOS laminator TFT increases the PPI from 233 to 314 retinal level. Realized the Micro LED HD display and low brightness controllable demand.

31‐1: Active Stylus Application Using Self‐Capacitive Touch with OLED TDDI

In this work, we propose active stylus application using selfcapacitive touch with OLED TDDI. Active stylus application using self‐capacitive touch sensor has several benefits in comparison to using mutual‐capacitive touch sensor, such as “Smaller RC Loading in Active Stylus Sensing”, “Uplink Signal Partially Driving”, and “Downlink Signal Through Palm Removing”. With these benefits, active stylus application can get better writing experience and accuracy using self‐capacitive on OLED On‐Cell product. Finally, we propose the word wide first OLED TDDI (Touch and Display Driver Integration) NT38770 passed Wacom LV1 certification with 6.67” OLED module.

Preview the Products on Display at Display Week 2023

Preview the Products on Display at Display Week 2023

P‐8.8: High Performance Video Stream Codec for High‐speed Digital Transmission in Display Driver Chips

Nowadays, as the vivid visual enjoyment requiring in mobile display devices exploding everywhere, enormous bandwidth pressure lands in all high-speed digital transmission interfaces, such as HDMI, MIPI, DP, eDP etc. A low latency in pixels’ time, flexible implementation for circuits, and high performance in visual quality video stream encoder and decoder (FHP-Codec) is proposed to relax the stress. The image structural features are analyzed, which directs an accurate 1D or 2D prediction reducing the redundancy utmost compared with DSC by 10~20% benefit in entropy, without obvious increments in circuit area and power consumption. According to the benchmark in Kodak image suite, FHP-Codec shows a considerable cost-performance ratio for display driver application fields.

P‐5.1: De‐Mura Processing with a High Performance for Low Grayscales in AMOLED Display

Mura artifacts reduction (De‐Mura) processing, with a high performance for low grayscales, is developed and integrated in display drivers for active‐matrix organic light‐emitting diode (AMOLED) display. The proposed De‐Mura processing, designed to compensate an AMOLED panel's luminance Mura (L‐Mura) and color Mura (C‐Mura), shows excellent display performance, and the major display properties include a diminished luminance non‐uniformity under low grayscales (<= Gray 16) and low luminous brightness (<= 2 cd/m 2 ), and an improved visually imperceptible color non‐uniformity. Our works reveals an effective solution to work around the inevitable difficulties of optical measurement of AMOLED panels under low luminous brightness.

A 10-Bit 20 Channel LCD Column Driver Using Compact DAC

A 20-channel liquid crystal display (LCD) driver architecture is implemented with [Formula: see text]m CMOS technology. This work presents a novel design of 10-bit compact and high-resolution two-stage DAC to improve the linearity and uniformity of each channel performance. A complete column driver, including a compact DAC, low power buffer, global R-string and multiplexing circuit design, is implemented, and the layout of this 20-channel, 10-bit LCD driver is generated using [Formula: see text]m CMOS technology. All the circuit blocks of the proposed LCD column driver were simulated using the EDA tool HSPICE and layout generation by Laker. This work also realizes a high-performance class AB operational amplifier with a gain of 140[Formula: see text]dB for the proposed LCD driver. The 10-bit compact LCD driver has a 1.4 mV LSB and an output voltage of 1.7 V is achieved for the input range of 0.25–1.7[Formula: see text]V. The compact DAC voltage selector with decoder in this design uses fewer switches in comparison to conventional tree-type RDAC, occupying a smaller chip area with fast response. The proposed design is sufficiently robust for high-color depth and resolution LCD driver applications. The experimental results exhibit maximum differential nonlinearity (DNL) and integral nonlinearity (INL) of 0.065 LSB and −0.12 LSB, respectively. The one channel area is [Formula: see text]m and the settling time is [Formula: see text]s for the [Formula: see text] and 20[Formula: see text]pF driving load.

A Compact Low-Voltage D-type Flip Flop Using Oxide TFTs and Its Application in Sequential Circuits

This brief presents a low-voltage D-type flip flop (D-FF) and its application in the sequential circuits, namely shift register (SR) and counter. These circuits were fabricated on a 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> thick polymide substrate using single-gate indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs). The proposed D-FF is designed using only 18 n-type transistors. This circuit has shown almost 100% improvement in frequency of operation compared to state-of-the-artwork from measurements at a low power supply voltage of 4V. In addition, the resulting 6-bit SR and 6-bit counter show expected functionality with the proposed D-FF. These circuits would find potential applications in display drivers and flexible smart sensing systems.

Integrated 0.35-µm CMOS Control Circuits for High-Performance Voltage Mode DC–DC Boost Converter

The integrated DC–DC converter is appropriate for use in many domains, namely, display, cellular, and portable applications. This paper presents an integrated control circuit for a monolithic voltage mode DC–DC boost converter for display driver applications. The control circuits consist of a transconductance amplifier, a comparator, and an oscillator. The boost converter consists of an inductor, two MOSFET, and an output RC filter. The control circuits are designed for fast transient response and low output ripple. The transconductance amplifier, comparator, and oscillator in the control circuit are designed to operate at a supply voltage of 3.3 V and an operating frequency of 5.5 MHz. The transconductance amplifier consists of an operational amplifier and an RC filter in the feedback path. The RC filter has a pole with a sufficient phase margin for high stability. The control circuits are realized in a 0.35-μm CMOS process together with the DC–DC converter. The fabricated DC–DC converter was evaluated by experiment and simulation. Testing of the proposed control circuits shows that the output transient time can be controlled within 7 μs, and the output voltage is accurately controlled with a ripple ratio of 3%.

(Invited) Achieving Lower Power Logic Using P-Type Metal Oxide Thin Film Transistors

Thin film transistors (TFTs) have enabled the active matrix displays that are a ubiquitous part of everyday life, from mobile phones and tablets through to desktop monitors and home televisions. They are used in the circuit at each pixel over the display as they can be fabricated for relatively low cost with excellent uniformity at low temperatures over large areas on glass substrates. These pixel circuits only require either n-channel or p-channel enhancement mode TFTs. However, there has long been a desire to integrate the display driver electronics onto the display panel as an alternative to connecting silicon-based integrated circuits using complementary metal oxide semiconductor (CMOS) field effect transistors (FETs) to displays. More recently, there has been an increasing interest in producing other logic circuits using TFTs on glass and plastic substrates as this could enable a new generation of products with embedded electronics. However, both of these applications need low power logic circuits. CMOS is an inherently low power technology, but it requires both n-channel and p-channel transistors. Whilst this can be realised in silicon CMOS FETs, it has not yet been achieved using TFTs because it has proved difficult to realise both n-channel and p-channel devices using one material system at low cost. For example, hydrogenated amorphous silicon can be used to make reasonable n-type material but not p-type.Thin film oxide semiconductors such as amorphous indium gallium zinc oxide have been successfully commercialised in the pixel circuits of active matrix displays as they possess high field effect mobility, low threshold voltage, low off-state current and a high switching ratio. There is therefore a lot of interest in finding a suitable complementary p-type metal oxide thin film material to allow CMOS-type logic to be realised using this material system.Cuprous oxide is one such promising candidate material as the top of the valence band is dominated by states which form as a result of hybridisation of the completely filled Cu 3d orbitals and the O 2p orbitals. These hybridised states are less localised and have a higher dispersion with a resulting decrease in the effective mass of holes in these states and a higher carrier mobility. The results of an extensive study of this material shows that the grain structure is of critical importance with [100] oriented films resulting in a higher mobility. Furthermore, the impact of grain boundaries on conduction must be controlled. Although this allows TFTs with reasonable on-state current to be fabricated, it is found that there is a significant residual off-state current which is a result of electron accumulation in the channel. This is consistent with the high off-state current that has been observed widely in TFTs using p-type metal oxide thin film materials.The low off-state current in silicon MOSFETs means that the geometric transistor design in low power CMOS logic circuits only needs to focus on the effect of the on-state current in the p-channel and n-channel transistors. However, in TFTs, the much larger off-state current also becomes important as it can end up being a significant parameter when calculating the power consumption of CMOS logic circuits. An alternative geometric design parameter for TFT logic circuits is presented. This compares the maximum switching current with the static currents allowing optimisation based on both the noise margin and static power consumption. The result is improved performance of TFT-based CMOS logic circuits using the n- and p-type thin film oxide semiconductors that are currently available.

P‐4.2: De‐Mura Processing Integrated in Display Drivers for AMOLED Display

High‐performance Mura artifact reduction (De‐Mura) processing is developed and integrated in display drivers for raising panel yield. The proposed De‐Mura processing, designed to compensate an active‐matrix organic light‐emitting diode (AMOLED) panel's luminance Mura (L‐Mura) and color Mura (C‐Mura), shows excellent display performance, and the major display properties include a diminished luminance nonuniformity from about 50% to about 10% under different gray levels, and an improved visually imperceptible color nonuniformity. Among 500 pieces of 5.83” (1128×2436, 460 PPI) retina AMOLED panels, panel yield is improved up to 96.8%. Our works reveals an effective external De‐Mura solution integrated in display drivers for panel factories and module suppliers to obtain high panel yield.

P‐1.6: 10000PPI Active Matrix Micro‐LED Driver Circuit Design

Micro‐LED display technology is an emerging display technology. Compared with liquid crystal display technology, silicon‐based liquid crystal technology, and OLED technology, Micro‐LED display with Micro‐LED technology has the advantages of fast corresponding speed, autonomous light emission, high contrast ratio, and long service life.This paper firstly introduces the driving method of Micro‐LED display technology, then introduces the method and design of the driving circuit using active addressable silicon‐based CMOS to build a dedicated Micro‐LED display, and finally gives the simulation results of the circuit, which can finally achieve the Micro‐LED driver applicable to 1920×1080 resolution, 120Hz, 10000PPI. display driver for 1920×1080 resolution, 120Hz, 10000PPI.

5.2: A Method of Noise Reduction Based on Adaptive Digital Filter for Touch Panel Data Processing

5.2: A Method of Noise Reduction Based on Adaptive Digital Filter for Touch Panel Data Processing

DDDMOSFET Performance Improvement by Gate Oxide Removal Followed by Silicided Source/Drain Formation in Gate Slots

In this work, the intentional insertion of slots in metal gate (MG) is introduced to solve the dishing issue for the double-diffused drain MOSFET (DDDMOSFET) fabrication. For traditional DDDMOSFET, the gate oxide layer in slots will be reserved to improve the device reliability, which requires an additional photomask to screen the gate/slot regions during the following sidewall formation and source/drain (S/D) implantation. This makes the process more complicated with increased cost. Without that additional photomask, it is proposed that the removal of gate oxide layer in slots can directly allow the floating S/D formation and the followed Ni silicidation there. It is demonstrated that such a novel process can not only relieve the MG dishing issue but can also effectively result in ~16% higher ON current and comparable OFF current for both N- and P-DDDMOSFETs without threshold voltage shift after applying electrical stress on gates. It is also revealed that the floating silicided S/Ds in slots have negligible influence on device breakdown characteristics. By saving one photomask, this work proposes a novel solution for the effective integration of core devices with very small feature sizes and high-voltage (HV) devices with large feature sizes in the same die, which is a common challenge for display driver chip fabrication using high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> /MG (HK/MG) technology.

A 5.2 Gb/s Receiver for Next-Generation 8K Displays in 180 nm CMOS Process

This article presents a high-speed receiver for next-generation 8K ultra-high-definition TVs. The receiver supports error-free communication between the timing controller and the display driver integrated circuits (DDIs) across various channels. Because the receiver must be co-integrated with pixel drivers in the DDI, it must be implemented in a process with high-voltage devices, which poses significant challenges in achieving beyond 5-Gb/s operation. We propose techniques for overcoming such process-induced speed limitations. They include a level-shifting passive continuous-time linear equalizer (CTLE), an active CTLE with extended bandwidth using a negative capacitor, a speculative decision feedback equalizer with a down-sampled edge-sampling path, and a low-dropout regulator with parallel error amplifiers to achieve all-band power supply rejection. A reference-less clock and data recovery circuit with a new frequency detector is also described. Fabricated in a 180-nm CMOS process, the prototype receiver operates at 5.2 Gb/s and can compensate up to 29-dB channel loss while consuming 120 mA from a 1.8-V supply.