• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.12
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• pp.31-38
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• 2010

This paper presents the design of a graphic memory for QVGA-scale LCD Driver IC (LDI). The graphic memory is designed based on the pseudo-SHAM for the purpose of small area, and the memory cell structure is designed using a bit line partitioning method to improve sensing characteristics and drivabilties in the line-read operation. Also, a collision protection circuit using C-gate is designed to control collisions between read/write operations and self-refresh/line-read operations effectively. The graphic memory circuit has been designed in transistor level using $0.18{\mu}m$ CMOS technology library and the operations of the graphic memory have been verified using Hspice. The results show that the bit-bitb line voltage difference, ${\Delta}V$ increases by 40%, the charge sharing time between bit and bitb voltages $T_{CHGSH}$ decreases by 30%, and the current during line-read decreases by 40%.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.2
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• pp.26-37
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• 2012

In this study, a power driver for actuating PVDF film that has the characteristic of dramatic impedance change caused by size and operating frequency variation was developed to dehyance rate of dredged sediment. In order to supply maximum energy to the PVDF film, a full-bridge circuit implemented using IGBT with a R-L-PVDF film impedance matching circuit was designed and constructed. the dehydration capabilities of the PVDF film actuated by the developed driver cleary was tested for dredged sediment. It was found that the PVDF film actuated by the developed driver cleary enhanced dehydration, avout three times faster during the first 3 minutes, compared to natural dehydration. The result of the experiment confirmed that the developed power driver for actuating Pvdf film could be used effectively for dehydration of dredged sediment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.702-708
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• 2020

Recently, as LED display systems have become larger, research on effective power control methods for the systems has been in progress. This paper proposes a power control method to minimize power loss due to the difference in LED characteristics for each channel of a backlight unit (BLU) system. The proposed LED driver IC has a power optimization function and detects the minimum headroom voltage for constant current operation of all channels and linearly controls the DC-DC converter output. Thus, it minimizes power consumption due to unnecessary additional voltage. In addition, it does not require a voltage sensing comparator or a voltage generation circuit for each channel. This has a great advantage in reducing the chip size and for stabilization when implementing an integrated circuit. In order to verify the proposed function, an IC was designed using Cadence and Synopsys' design tools, and it was fabricated with a Magnachip 0.35um 5V/40V CMOS process. The experiments confirmed that the proposed power control method controls the minimum required voltage of the BLU system.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.967_968
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• 2009

For lighting application, high-power LED nowadays is driven at 350mA and a sensing resistor is used to provide feedback for LED-current regulation. This method adds an IR drop at the output branch, and limits power efficiency as LED current is large and keeps increasing. In this paper, a power efficient LED-current sensing circuit is proposed. The circuit does not use any sensing resistor but extracts LED-current information from the output capacitor of the driver. Controlling the brightness of LEDs requires a driver that provides a constant, regulated current. In one case, the converter may need to step down the input voltage, and, in another, it may need to boost up the output voltage. These situations often arise in applications with wide-ranging ""dirty"" input power sources, such as automotive systems. And, the driver topology must be able to generate a large enough output voltage to forward bias the LEDs. So, to provide this requirements, 13W prototype Buck-Boost Converter is used.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.1
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• pp.34-40
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• 1998

For applicating to 10-Gbit/s optical transimission systems, we have designed and fabricated a laser driver IC with extremely-high-operation-frequencies using AlGaAs/GaAs heterojunction bipolar transistors (HBTs), and have investigated its performances. Circuits design andsimulation were performed using SPICE and LIBRA. A discrete AlGaAs/GaAs HBT with the emitter area of 1.5*10 .mu.m$^{2}$, used for the circuit fabrication, exhibited cutoff frequency of 63 GHz andmaximum osciallation frquency of 50 GHZ. After fabrication of MMICs, we observed the very wide bandwidth of DC~18 GHz and the S$_{21}$ gain of 17 dB for a laser driver IC from the on-wafer measurement. Metal-packaged laser driver IC showed the excellent eye opening, the modulation currents of 32 mA, the rise/fall time of 40 ps, measured at the data rates of 10-Gbit/s.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.572-575
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• 2009

In this study, we proposed WLED(White-Light Emitting Diode) driver IC for mobile applications. This IC drove WLED for mobile applications with low input voltage and high efficiency by using boost converter. The device was designed by using boost converter applied current-mode control algorithm and provided PWM(Pulse Width Modulation) & analog dimming. Designed IC consisted of bias block, drive block, control block, protection block. We confirmed this device worked well through a application PCB (Printed Circuit Board) test.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1474-1480
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• 2017

This paper presents a new LED current balancing scheme using double-step-down dc-dc converter. With the proposed structure, the two channel LED currents are automatically balanced without using any dedicated control or auxiliary circuit. In addition, switching loss of the switching devices in the proposed LED driver is lower than that of the conventional buck LED driver. To verify the operation of the proposed LED driver, a hardware prototype is built and tested with different number of LED.

• Journal of Information Display
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• v.6 no.1
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• pp.12-16
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• 2005

Gate and data drivers are essential for driving active matrix display. In this study, we integrate drivers with a-Si:H to develop a compact, better reliability and cost effective display. We design and fabricate drivers with conventional a-Si:H thin film transistors (TFTs). The output voltages are investigated according to the input voltage, temperature and operation time. Based on these studies, we propose here a new driver to prevent gate line from the floated state. For the external coupled voltage fluctuation, the proposed driver shows better stability.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.81-83
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• 2006

The conventional cold cathode fluorescent lamp (CCFL) driver for LCD TV has a transformer for each lamp to step up the high sinusoidal waveform from the low input voltage. The transformer used in the conventional topology causes the driver to have bulky size and high cost. This paper proposes a new transformer-less CCFL driver for LCD backlight that is based on the parallel-loaded resonant inverter topology. This resonant topology enables the circuit to supply enough high voltage for CCFL without a transformer. Also, with current-balancing technique, this transformer-less inverter drives 16 CCFL lamps.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.3
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• pp.390-396
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• 2015

This paper proposes a method to reduce flicker when running an AC-power direct-drive type multiple string LED driver IC. The proposed method greatly decreases flicker using one capacitor and P-type MOSFET transistor (PMOS). The flicker index (FI) was reduced by over 40% through experiments, and less than half of the conventional external components are used in the passive valley fill circuit, which gives an advantage in the cost and utilization in the design of LED lighting modules. The 0.35 um 700 V BCD process was used to manufacture this LED driver.