• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.186-190
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• 2016

In this study, we fabricated the transparent photovoltaic device using 2-dimensional transition-metal dichalcogenides and investigated the transparency and photovoltaic characteristics. P-n heterojunction was formed by mechanical exfoliation and aligned transfer method on the transparent sheet using n-type $MoS_2$ and p-type $WSe_2$. Our transparent photovoltaic device exhibited the open-circuit voltage of ~ 0.15 V and the short-circuit current of 0.48 nA under illumination of white light.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.57-58
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• 2005

The properties such as capacitance and resonant frequency are important in embedded capacitors. Accurate equivalent model is required to find these properties of embedded capacitor. In this paper, we investigate to analyze the properties of high-K embedded capacitor which was fabricated by Low Temperature Co-fired Ceramic (LTCC). Modeling based on partial element equivalent circuit (PEEC) method is performed using HSPICE circuit simulation. This modeling methodology can provide the good inspection of embedded capacitor to device engineer.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.4
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• pp.266-274
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• 2024

In this paper, we designed a low-area 32-bit PF (Poly-fuse) OTP IP, a non-volatile memory that stores data required for analog circuit trimming and calibration. Since one OTP cell is constructed using two PFs in one select transistor, a 1cell-2bit multibit PF OTP cell that can program 2bits of data is proposed. The bitcell size of the proposed 1cell-2bit PF OTP cell is 1/2 of 12.69㎛ × 3.48㎛ (=44.161㎛2), reducing the cell area by 33% compared to that of the existing PF OTP cell. In addition, in this paper, a new 1 row × 32 column cell array circuit and core circuit (WL driving circuit, BL driving circuit, BL switch circuit, and DL sense amplifier circuit) are proposed to meet the operation of the proposed multbit cell. The layout size of the 32bit OTP IP using the proposed multibit cell is 238.47㎛ × 156.52㎛ (=0.0373㎛2) is reduced by about 33% compared that of the existing 32bit PF OTP IP using a single bitcell, which is 386.87㎛ × 144.87㎛ (=0.056㎛2). The 32-bit PF OTP IP, designed with 10 years of data retention time in mind, is designed with a minimum programmed PF sensing resistance of 10.5㏀ in the detection read mode and of 5.3 ㏀ in the read mode, respectively, as a result of post-layout simulation of the test chip.

• Journal of Radiation Protection and Research
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• v.25 no.4
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• pp.197-205
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• 2000

A prototype electronic dosimeter(PED) adopting a silicon PIN diode detector as a radiation detector has been developed, manufactured and test-evaluated. A radiation signal processing circuit has been electronically tested and then the radiation detection characteristics of this PED has been performance-tested by using a reference photon radiation field. As a result in a electronic performance test, radiation signals from a detector were well observed in the signal processing circuit. The radiation detection sensitivity of this PED after several test-irradiations to $^{137}Cs$ gamma radiation source appeared to be 1.85 cps/$Gy{\cdot}h^{-1}$ with 19.3% of the coefficient of variation, which satisfied the performance criteria for the active personnel radiation monitor. Further improvement of the electronic circuit and operating program will enable the PED to be used in personal monitoring purpose.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.11
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• pp.7-13
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• 2002

BSCT 320${\times}$240 IRFPA detector module is implemented, which is a key component in uncooled thermal imaging systems. The detector module consists of two parts, infrared sensitive pixel array and read-out integrated circuit(ROIC). The BSCT 320${\times}$240 pixels are made by laser scribe process and 10-${\mu}m$ micro-bump to satisfy 50-${\mu}m$ pitch and 95-% fill-factor. The ROIC has been designed to electrically address the pixels sequentailly and to improve signal-to-noise ratio with single transistor amplifier, HPF, tunable LPF and clamp circuit. The fabricated hybrid chip of detector and ROIC has been mounted on the TEC built-in ceramic package for more stable operation and tested for lots of electrical and optical properties. The IRFA sample has shown successful properties and met with good results of fill-factor, detectivity and responsivity.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.3
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• pp.205-210
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• 2022

A novel OLED pixel circuit is proposed in this paper that uses only n-type thin-film transistors(TFTs) to improve the luminance non-uniformity of the AMOLED display caused by the threshold voltage variation of an OLED driving TFT. The proposed OLED pixel circuit is composed of 6 n-channel TFTs and 2 capacitors. The operation of the proposed OLED pixel circuit consists of the capacitor initializing period, threshold voltage sensing period of an OLED·driving TFT, image data voltage writing period, and OLED·emitting period. As a result of SmartSpice simulation, when the threshold voltage of·OLED·driving TFT varies from 1.2 V to 1.8 V, the proposed OLED pixel circuit has a maximum current error of 5.18 % at IOLED = 1 nA. And, when the OLED cathode voltage rises by 0.1 V, the proposed OLED pixel circuit has very little change in the OLED current compared to the conventional OLED pixel circuit. Therefore, the proposed pixel circuit exhibits superior compensation characteristics for the threshold voltage variation of an OLED driving TFT and the rise of the OLED cathode voltage compared to the conventional OLED pixel circuit.

• Journal of IKEEE
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• v.24 no.1
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• pp.132-139
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• 2020

The ionizer module used in this air cleaner supplies high voltages of 3.5KV / -4KV to the discharge electrode HV+ / HV- using a winding transformer to generate positive and negative ions by electric field radiation of carbon fiber brush. The ionizer module circuit using the existing MCU has the disadvantage of large PCB size and expensive price, and the gate driver chip using the existing ring oscillator has oscillation period sensitive to PVT (Process-Voltage-Temperature) fluctuation and there is risk of fire or electric shock because there is no fault detection function by short circuit of HV+ and GND as well as HV- and GND. Therefore, in this paper, even though PVT fluctuates, by using 7-bit binary up counter, HV+ voltage reaches the target voltage by adjusting oscillation period. And an HV+ short fault detection circuit for detecting a short circuit between HV+ and GND, an HV- short fault detection circuit for detecting a short circuit between HV- and GND, and an OVP (Over-Voltage Protection) for detecting that HV+ rises above an overvoltage are newly proposed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.1
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• pp.99-105
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• 2019

OBC for battery charging of electric vehicles mainly consist of two stages including PFC circuit and isolated DC-DC converter circuit. In general, a non-isolated boost converter is used as the PFC circuit, and a resonant converter capable of ZVS (zero voltage switching) is used as the isolated DC-DC converter. In this paper, we propose an OBC composed of isolated current-fed type PFC circuit and buck DC-DC converter. The proposed OBC is easy to configure the circuit and controller, and can cope with a wide output range. In order to verify the validity of the proposed circuit, a prototype 3.3 ㎾ class prototype was fabricated. As a result, the maximum efficiency and the maximum power factor of 99.2% were confirmed under the operational stability and rated load conditions at the output voltage of 150V ~ 400V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.593-600
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• 2010

In this paper, High brightness LED (light-emitting diodes) driver IC (integrated circuit) using new current sensing circuit is proposed. This LED driver IC can provide a constant current with high current precision over a wide input voltage range. The proposed current-sensing circuit is composed of a cascode current sensor and a current comparator with only one reference voltage. This IC minimizes the voltage stress of the MOSFET (metal oxide semiconductor field effect transistor) from the maximum input voltage and has low power consumption and chip area by using simple-structured comparator and minimum bias current. To confirm the functioning and characteristics of our proposed LED driver IC, we designed a buck converter. The LED current ripple of the designed IC is in ${\pm}5%$ and a tolerance of the average LED current is lower than 2.43%. This shows much improved feature than the previous method. Also, protections for input voltage and operating temperature are designed to improve the reliability of the designed IC. Designed LED driver IC uses 1.0 ${\mu}m$ X-Fab. BiCMOS process parameters and electrical characteristics and functioning are verified by spectre (Cadence) simulation.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.512-517
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• 1998

In a matrix converter, input side and output side are coupled with each other through switching elements. Since disturbances on either side affect directly on the other side, it requires a high-speed on-line control system to compensate them. We proposed in previous papers a new control strategy and an on-line control circuit for a matrix converter. The control circuit could keep the output voltage at commanded value against fluctuation in the supply voltage. Furthermore wave forms of the output voltage and the input current were always kept sinusoidal. The switching pattern was generated by comparing modified voltage references with a carrier. The carrier was synchronized with the supply voltage using a PLL system, which made the control circuit complicated and costly. This paper discusses on the possibility of an asynchronized carrier. Experiment results show the input current distortion in case of asynchronous carrier is bigger than that of synchronous carrier. However, the deterioration can be minimized by increased carrier frequency.