Micro LED and Large-Size Display Driver IC Technology

Zhe Zhang, Zhizheng Huang, Lei Fan*, Qian Bi, Li Zhang
(Beijing Chipone Technology Co., Ltd., Beijing 100176, China)

Abstract: Micro LED, as a representative technology of ultra-fine pitch displays, has become a major research focus in the display industry. It offers numerous advantages, including self-emissive properties, high efficiency, low power consumption, high integration, and strong stability. With its compact size, high flexibility, and ease of disassembly and integration, Micro LED can be applied across a full range of display scenarios—from small-format to large-format applications. Many companies have introduced Micro LED display prototypes and demonstration systems to the market; however, the technology still has significant room for further development.

This paper reviews the development history of Micro LED display technology, summarizes its current progress, and discusses the key technical challenges it faces, such as mass transfer and full-color implementation. It further explains the display principles and driving architecture, and, in conjunction with Chipone’s Micro LED driver IC solutions, outlines the current status of large-size Micro LED chip technology. Finally, the paper offers insights and perspectives on the future applications and development of Micro LED technology.

Keywords: Micro LED; high integration; driver architecture; mass transfer; full-color implementation.

1 Introduction

With the advancement of display technology, user demands for display screens have continued to rise, showing clear trends toward higher resolution, miniaturization, and greater integration. Displays are now widely used in smartphones, tablets, monitors, televisions, data projectors, and augmented reality devices, among other applications.

From early LCD technology to OLED, and now to Mini LED and Micro LED—currently key research focuses—the evolution has taken place within just a few decades. Each display technology has its own strengths and challenges and demonstrates unique advantages in different application sectors. Traditional LCDs offer long lifespans and low cost but are limited in contrast and flexibility, and are now mainly used in industries where high display precision is not required. OLED displays provide unprecedented deep blacks and ultra-thin form factors, but they suffer from relatively short lifespans and significant aging issues. Mini LED, derived from the development of Micro LED, can be regarded as a transitional technology toward Micro LED and has played a role in advancing its progress. Compared with other display technologies, Micro LED not only offers a long lifespan but also high brightness, high compatibility, high resolution, and high color saturation. With self-emissive and sensing capabilities, it is considered an ideal display technology [1–4].

The greatest advantage of Micro LED over other display technologies lies in its micron-level pixel pitch. Each pixel can be individually addressed and independently driven, enabling higher luminous efficiency and greater luminous energy density than other LED products. This makes it especially suitable for miniaturized displays, flexible screens, and ultra-large displays, delivering superior visual performance.

Although Micro LED demonstrates excellent performance and theoretically enables superior RGB full-color realization, numerous technical challenges remain. These include mass transfer, full-color display implementation, irreparable defects, and microfabrication process limitations [5–8]. These challenges result in low production yield, high cost, and difficulty in large-scale manufacturing. Therefore, for Micro LED products to dominate the market, further technological breakthroughs are required to overcome these barriers and meet market demand.

This paper reviews the development history of Micro LED display technology, summarizes its current market status, analyzes manufacturing process barriers, explains LED display principles and driving architectures, and—based on integrated Micro LED driver IC solutions—introduces the latest research technologies. Finally, it provides an outlook on the future development of Micro LED display technology.

1 Development History of Micro LED

The concept of Micro LED was first proposed in 2000 by Professors Hong Xingjiang and Jiangyu Lin of Texas Tech University [9]. Subsequently, manufacturers worldwide began investing in Micro LED research.

As early as 2001, H. X. Jiang’s team innovatively developed a 10 × 10 Micro LED array based on PM OLED technology, using 100 fully independent p-electrodes and four shared n-electrodes. Through optimized interconnection structures and layout design, they successfully addressed display resolution challenges.

Soon after, multiple research teams published further progress in Micro LED technology. In 2008, the team led by Y. Fan [10] introduced a Micro LED chip measuring 3.2 mm × 3.2 mm, featuring a 120 × 120 PM OLED-based micro-array with pixel sizes of 20 μm × 12 μm and a pixel pitch of only 22 μm. Although the array layout and wiring remained complex, significant improvements were made in device miniaturization.

Zhengzhou University integrated 370 nm UV Micro LED arrays and 470 nm blue Micro LED arrays using flip-chip bonding technology. By stimulating red and green quantum dots with UV LEDs, the feasibility of quantum dot color conversion was successfully validated.

In December 2011, the Texas Tech University team combined Micro LED technology with complementary metal-oxide-semiconductor (CMOS) circuitry to manufacture large-scale integrated circuit chips with read/write functionality. The result was a video graphics array display with extremely high resolution and rapid color response.

In academic research, Micro LED technology has continued to iterate toward smaller chip sizes and higher resolution. In the commercial market, more manufacturers have entered the field and introduced their own products.

In 2012, Sony officially released the 55-inch Crystal LED television, demonstrating its leadership in Micro LED display technology. LuxVue conducted early specialized research on Micro LED and produced miniaturized display panels using traditional integrated circuit processes and vapor deposition methods. In 2014, Apple acquired LuxVue and began focusing heavily on Micro LED development. This acquisition not only validated the feasibility and inevitability of Micro LED technology but also brought it into the mainstream spotlight.

Apple subsequently established extensive patent portfolios covering Micro LED chip efficiency, color conversion/generation, light management, display architecture, testing, and sensor integration. For example, in 2017, Apple was granted a patent for infrared sensing diode processing technology capable of reading fingerprints on the display surface. Based on Micro LED technology, this approach enables Touch ID integration directly into the entire screen.

Although Apple has continuously advanced its Micro LED R&D efforts over the years, challenges such as mass transfer, micro-scale chip and epitaxial processes, full-color implementation, high costs, and supply chain ecosystem development may impact its proprietary Micro LED roadmap.

In December 2020, Samsung launched a 110-inch Micro LED television, initially pre-selling it in the South Korean market before expanding to global markets.

A wave of enthusiasm for Micro LED research has emerged, with major domestic manufacturers actively investing in the field and achieving breakthrough progress.

In 2017, leading panel maker BOE Technology Group publicly announced that it had initiated research on Micro LED technology and had made notable progress. In 2018, China Star Optoelectronics Technology (CSOT) introduced the world’s first AM-Mini LED RGB full-color display based on an IGZO-TFT glass transparent substrate at the 20th China Hi-Tech Fair, marking a significant breakthrough and demonstration for large-size Micro LED backplane and display development. In the same year, Visionox—traditionally focused on OLED—began actively developing Micro LED and showcased its first Micro LED prototype.

At Display Week in the United States in May 2019, panel manufacturer Tianma Microelectronics exhibited a transparent full-color Micro LED display, winning the People’s Choice Award. Meanwhile, Refond Optoelectronics advanced both Mini LED and Micro LED dedicated and common technologies, maintained collaboration with domestic and international R&D institutions, and worked with HiSilicon to support mass production process optimization of Mini LED backlights, contributing to Huawei’s “three-screen” strategy.

In addition, domestic chip packaging leaders such as NationStar Optoelectronics, MLS (Mulinsen), and Hongli Zhihui have entered the fine-pitch and Mini LED direct-view market, achieving significant commercial gains.

At CES 2025, Samsung officially unveiled its 2025 TV product lineup, which includes RGB Micro LED televisions. The company also demonstrated a 2.1-inch Micro LED display designed for smartwatches and a stretchable Micro LED concept display. Hisense showcased a transparent Micro LED display, while Innolux introduced the industry’s first color-conversion 106-inch AM-Micro LED modular splicing display. RayNeo Innovation released its RayNeo V3 AI smart glasses equipped with a full-color Micro LED light engine. Vuzix presented its latest Micro LED AR smart glasses design. Sitan Technology exhibited Micro LED display modules for AR, automotive, and projection applications.

2 Key Technologies of Micro LED

At present, through collaborative efforts and technical breakthroughs by research institutions and enterprises both domestically and internationally, Micro LED technology has achieved significant progress. However, certain manufacturing challenges remain, particularly in backplane technology, full-color implementation, and mass transfer.

2.1 Backplane Technology

Backplanes can be categorized into four types: glass substrates, flexible substrates, silicon substrates, and PCBs. Initially, PCB backplanes were the most widely used due to their large size compatibility. They allow modular splicing to meet various size requirements and enable material selection based on application needs.

However, as pixel density increases, the precision of PCB fabrication processes has become insufficient to meet performance requirements, resulting in significantly lower yield rates, longer production cycles, and higher display costs. Meanwhile, decreasing pixel pitch presents additional challenges for PCB routing design. Within the same display area, higher resolution requires a substantial increase in column lines—approximately three times the number of added LEDs per column. As line spacing narrows and routing complexity rises, higher precision is demanded from manufacturing equipment, further reducing substrate yield.

To address these issues, alternative lamp-board architecture solutions have been proposed based on the traditional LED chip + PCB substrate + driver IC structure, including Die In Substrate and Die On Substrate architectures (as shown in Figure 2).

(1) Die In Substrate
This packaging architecture consists of an upper substrate, a driver IC template, and a lower substrate. The upper substrate is used for soldering LED chips or packaged LEDs, while the lower substrate handles power and signal pads. The driver IC template is directly embedded within the packaging substrate. From surface mounting to the lamp-board PCB, the overall structure can be simplified to just two layers.

(2) Die On Substrate
In this architecture, the driver IC and LED chips are placed on the same side of the substrate, using single-sided soldering with one-time transfer. This approach improves production efficiency while reducing substrate cost and manufacturing complexity.

2.2 Full-Color Implementation

There are two primary approaches to achieving full-color Micro LED displays. One solution utilizes blue LED chips combined with color-conversion quantum dots or phosphor materials. However, challenges such as coating uniformity and material reliability still need to be resolved, limiting its widespread application.

The other solution directly employs RGB (red, green, and blue) LED chips, which is currently the dominant method used in most large-format displays. The RGB colorization principle is based on the additive mixing of the three primary colors—red, green, and blue—and variations in their respective channels to generate a broad range of colors [1]. Under this principle, different levels of current are applied to each of the three primary-color LEDs to control their brightness. By combining and superimposing red, green, and blue light at varying intensities, full-color display output is achieved [12–14]. Figure 3 illustrates the different approaches to colorization technology.

The integration of advanced color technologies enables Micro LED displays to achieve high resolution, high brightness, and an exceptionally wide color gamut. Their ultra-fast dynamic response also reduces display latency during image transitions. As a result, Micro LED technology surpasses other display technologies in visual performance, delivering rich and highly immersive image quality.

However, in Micro LED displays, the size of red, green, and blue LED chips must be correspondingly reduced to fit within the limited unit area. In addition, RGB LED chips exhibit differences in luminous efficiency and driving current requirements. To ensure current stability, pulse-width modulation (PWM) control is typically used to regulate the average current of each chip and achieve accurate color mixing. Furthermore, due to wavelength uniformity variations among the different colors, the RGB three-chip approach in Micro LED applications still faces challenges related to optical efficiency and production yield.

2.3 Mass Transfer

The fabrication process of Micro LED displays is highly complex. In addition to miniaturizing and arraying traditional light-emitting diodes, a massive number of micro-scale LED chips must be precisely transferred onto the target LED circuit substrate. During the transfer process, ultra-fine pixel spacing must be maintained to meet high-resolution requirements.

For a 4K display, more than 20 million Micro LED chips must be flip-chip bonded, while an 8K display requires the placement of over 100 million Micro LED chips. Such large-scale chip transfer places extremely high demands on transfer accuracy, transfer speed, and color uniformity control.

Mass transfer primarily refers to transferring large quantities of micro-LED dies onto a substrate through methods such as pick-and-place or adhesion-based techniques. The core challenges lie in achieving high efficiency and high yield. Various transfer technologies are currently available on the market, as shown in Figure 4, including precision pick-and-place technology, laser release technology, fluidic self-assembly technology, and roller transfer printing technology [11]. Although these approaches differ in implementation, they share a common requirement for extremely high transfer precision to improve overall Micro LED production yield.

Precision pick-and-place technology employs different transfer heads and utilizes van der Waals forces, magnetic forces, or electrostatic forces to adsorb and transfer large numbers of Micro LED chips. This method requires exceptionally high equipment precision and stability.

Laser release technology may cause surface damage to the chips—such as indentations or cracks—during the transfer process, potentially reducing yield. Additionally, laser equipment is expensive, increasing overall production costs.

Fluidic self-assembly technology relies on fluid drag forces to transfer Micro LED chips onto the backplane. However, the process typically requires three transfer stages to complete, resulting in relatively low efficiency.

Roller transfer printing technology uses a soft roller stamp to transfer Micro LED chips onto the backplane. While it enables transfer onto flexible substrates, it also generally requires three transfer steps to complete the process.

Existing mass transfer technologies are still insufficient to handle the large-scale transfer of Micro LED chips. Further optimization in transfer accuracy, transfer speed, process technology, and manufacturing cost is required to meet the demands of Micro LED display fabrication.

3 Principles and Architecture of Display Driving Technology

3.1 Display Principle

A display module consists of multiple display units, control circuits, power converters, and supporting structural components. One or more display modules can be spliced together to form an LED screen body. The LED screen body is controlled by a display control system to render images—this constitutes an LED display.

Since LEDs (light-emitting diodes) feature unidirectional conduction and rapid switching characteristics, the control system manages row and column driving circuits to indirectly control the on/off timing and frequency of individual primary-color pixels at high speed (pixel-level control). Through this method, vibrant and full-color images can be displayed on the LED screen.

3.2 Driving Architecture

Row-column scanning is a commonly used driving method for dot-matrix LED display devices. In this architecture, the anodes of LEDs in each horizontal row are connected together, while the cathodes in each vertical column are connected together. When a driving signal is applied to a specific row, whether each LED in that row is illuminated depends on the control signal applied to its corresponding column.

In row-column scanning, each control circuit drives only one row of LEDs at a time. By scanning rows sequentially and synchronously changing the control signals for each column, information is displayed across the panel matrix. When the scanning frequency is sufficiently high, the persistence of vision of the human eye allows the viewer to perceive a complete image.

Based on the current-voltage characteristics of LEDs, driver ICs can be categorized into constant-voltage and constant-current driving types [15]. Constant-voltage driving applies a fixed voltage across the LED terminals, while constant-current driving supplies a steady current to control light emission. Because constant-voltage driving has limitations in dot-matrix modules, low-end single- and dual-color displays, and display consistency, constant-current driving has become the mainstream approach for full-color displays.

Within constant-current driving, and depending on packaging and circuit structure, two main architectures are used: common-anode and common-cathode driving. As shown in Figures 5(a) and 5(b), in a common-anode configuration, the anode of each LED is connected to the row line as the common terminal, while the cathode is connected to the constant-current column driver. In contrast, in a common-cathode configuration, the cathode of each LED is connected to the row line as the common terminal, and the anode is connected to the constant-current column driver.

The current flow directions for the two architectures are illustrated in Figure 5(c). In common-anode driving, current flows from VCC to the row transistor, then to the LED, to the driver IC, and finally to ground (GND). In common-cathode driving, current flows from VCC to the driver IC, then to the LED, to the row transistor, and finally to ground.

In a common-anode LED display system, the red, green, and blue LEDs within a single pixel typically share the same power supply, meaning they operate at the same supply voltage. However, due to the optoelectronic characteristics of LEDs, red LEDs require a lower driving voltage than green and blue LEDs. To ensure balanced heat generation and stable operation of the driver IC, additional external bias resistors must be added to share the voltage drop, resulting in energy loss in the form of heat. Consequently, common-anode designs generate more heat, requiring active cooling solutions and increasing PCB routing complexity.

In contrast, in a common-cathode driving architecture, the red LED and the green/blue LEDs within a single pixel can use separate power supplies. This eliminates the need for additional bias resistors to distribute voltage drops, resulting in lower heat generation and simpler PCB routing. Due to its advantages—including reduced heat, lower power consumption, and improved display consistency—the common-cathode driving approach has been increasingly adopted by display and driver IC manufacturers. As a leading domestic driver IC design company, Chipone Technology currently offers multiple product lines supporting both common-cathode and common-anode driving architectures [16].

4 Display Driver IC

Micro LED technology has attracted widespread attention due to its unique display characteristics, high image quality, efficient energy utilization, and long lifespan. Major manufacturers have actively invested in their research and development. Although integration processes still require further improvement, significant breakthroughs have continued to emerge.

Our research team has focused on a series of key Micro LED technologies and achieved notable progress, which has been successfully applied to large-format Micro LED display products. For small-sized, ultra-fine pitch displays, our team has also designed a silicon-based OLED (Micro OLED) display driver IC that supports multiple technical solution architectures.

Chipone Technology has developed driver ICs specifically for large-size Mini LED and Micro LED displays. These ICs adopt an innovative integrated architecture and utilize a high-speed Mini-LVDS data transmission interface, simplifying module circuit design and providing customers with comprehensive Mini/Micro LED display control solutions.

This driver chip employs a common-cathode architecture for full-color LED displays. The red LEDs and the green/blue LEDs operate at different supply voltages. Key specifications are summarized in Table 1. The driver IC features an extremely fast turn-on time of just 20 ns and supports a high current gain range from 12.5% to 200%. The chip offers high current accuracy, with a current error of only ±1.0%.

It adopts an integrated row-column driving design, incorporating 360 channels of constant-current column drivers and 180 channels of NMOS constant-current outputs, supporting scanning modes from 1 to 90. A single IC can control 120 × 90 pixels, buffer 16-bit input data, and convert it into grayscale output. Optimized PWM output improves low-grayscale display uniformity.

The chip integrates built-in grayscale clock technology to significantly reduce system-level electromagnetic interference (EMI). It also incorporates LED open-circuit detection, proprietary upper and lower ghost-image elimination circuitry, and dynamic energy-saving modules. These features effectively address common fine-pitch display issues such as high-contrast interference, dark lines, low-grayscale speckling, and cross-panel coupling, enhancing overall integration, data processing consistency, and image performance.

Additionally, the driver IC supports dynamic power saving, black-screen energy saving, and the elimination of unnecessary power consumption, further improving overall system efficiency.

The chip is packaged using BGA (Ball Grid Array) surface-mount technology. The entire bottom surface of the device can be utilized for solder ball connections. Compared with other packaging technologies, BGA offers higher pin density, lower thermal impedance, shorter average lead length, and reduced inductance. By adopting a packaging design with different internal and peripheral pin pitches, a total of 656 pins are implemented, significantly enhancing chip integration and high-speed performance.

As shown in Figure 6, the system block diagram of the driver IC includes the following modules:
• mLVDS IN and mLVDS OUT: Low-voltage differential signal input/output interfaces. Compared with traditional data interfaces, they provide higher transmission speed and lower power consumption, greatly simplifying the original circuit structure.
• GPLL (General Phase-Locked Loop): Processes the received clock signals. The internally generated grayscale clock further optimizes EMI performance.
• Time Control: A timing control module responsible for managing signal timing across the entire chip. It integrates proprietary display algorithms developed by Chipone, further enhancing display performance.
• Digital Control and SRAM: Display data processing units. In addition to standard display data, they support calibration data and open/short circuit detection data.
• Scan Driver: The row scanning driver module. It supports arbitrary scanning modes from 1 to 90 and allows flexible configuration of multiple scanning schemes.
• RGB Driver: The constant-current driving module. Its wide current range supports various pixel pitch applications, and through Chipone’s proprietary design, current accuracy reaches ±1%.

(1) Common-Cathode Driving
The chip adopts a common-cathode driving architecture and does not require external resistors. Three groups of constant-current output values—R, G, and B—can be configured through registers, enabling lower overall power consumption and improved display uniformity.

(2) Current Accuracy
The chip utilizes advanced precision current control technology, ensuring virtually no current variation from channel to channel or from IC to IC. The maximum channel-to-channel current deviation is ±1.0%, and the maximum IC-to-IC current deviation is also ±1.0%. The output stage current characteristics remain stable; regardless of variations in LED forward voltage, a constant current is maintained.

(3) Mini-LVDS
Mini-LVDS is a high-speed serial interface used to connect the timing controller and the column drivers. It generates very low electromagnetic interference (EMI) while providing high bandwidth for display driving. By integrating the Mini-LVDS high-speed data interface into the chip, the link supports greater loading capacity, simplifies signal transmission, and improves overall data transfer efficiency.