• Journal of IKEEE
• /
• v.17 no.3
• /
• pp.267-274
• /
• 2013

This paper presents a design of LLC resonant converter IC for LED backlight unit based on PFM/PWM dual-mode feedback. Dual output LLC resonant architecture with a single inductor is proposed, where the master output is controlled by the PFM and slave output is controlled by the PWM. To regulate the master output PFM is used as feedback to control the frequency of the power switch. On the other hand, PWM feedback is used to control the pulse width of the power switch and to regulate the slave output. This chip is fabricated in 0.35um 2P3M BC(Bipolar-CMOS-DMOS) Process and the die area is $2.3mm{\times}2.2mm$. Current consumptions is 26mA from 5V supply.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.4
• /
• pp.19-27
• /
• 2007

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost H-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switch mode equivalent circuits and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft-switching(ZVS) operation ranges, and the power dissipation as compared with those of the conventional type high frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation(PWM) and pulse density modulation(PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.307-307
• /
• 2013

초고집적 회로에 적용되는 반도체 소자의critical dimension (CD)이 수 nano 사이즈로 줄어들고 있기 때문에, 다양한 물질의 식각을 할 때, 건식식각의 중요성이 더 강조되고 있다. 특히 $SiO_2$와 같은 유전체 물질을 식각할 때, plasma process induced damages (P2IDs)가 관찰되어 왔고, 이러한 P2IDs를 줄이기 위해, pulsed-time modulation plasma가 광범위하게 연구되어 왔다. Pulsed plasma는 정기적으로 radio frequency (RF) power on과 off를 반복하여 rf power가 off된 동안, 평균전자 온도를 낮춤으로써, 웨이퍼로 입사되는 전하 축적을 효과적으로 줄일 수 있다. 또한 fluorocarbon plasmas를 사용하여 $SiO_2$를 식각하기 위해 Dual-Frequency Capacitive coupled plasma (DF-CCP)도 널리 연구되어 왔는데, 이것은 기존의 방법과는 다르게 plasma 밀도와 ion bombardment energy를 독립적으로 조절 가능하다는 장점이 있어서 미세 패턴을 식각할 때 효과적이다. 본 연구에서는 Source power에는 60 MHz pulsed radio frequency (RF)를, bias power에는 2 MHz continuous wave (CW) rf power가 사용된 system에서 Ar/$C_4$ F8/$O_2$ 가스 조합으로, amorphous carbon layer (ACL)가 hard mask로 사용된 $SiO_2$를 식각했다. 그리고 source pulse의 duty ratio와 pulse frequency의 효과에 따른 $SiO_2$의 식각특성을 연구하였다. 그 결과, duty ratio의 감소에 따라 $SiO_2$, ACL의 etch rate이 감소했지만, $SiO_2$/ACL의 etch selectivity는 증가하였다. 반면에 pulse frequency의 변화에 따른 두 물질의 etch selectivity는 크게 변화가 없었다. 그 이유는 pulse 조건인 duty ratio의 감소가 전자 온도 및 전자 에너지를 낮춰 $C_2F8$가스의 분해를 감소시켰으며, 이로 인해 식각된 $SiO_2$의 surface와 sidewall에 fluorocarbon polymer의 형성이 증가하였기 때문이다. 또한 duty ratio의 감소에 따라 etch selectivity뿐만 아니라 etch profile까지 향상되는 것을 확인할 수 있었다.

• Journal of Power Electronics
• /
• v.14 no.6
• /
• pp.1217-1223
• /
• 2014

A novel half load-cycle worked dual input single output (DISO) DC/AC inverter is presented. The basic circuit consists of a dual buck regulator, which works in continuous current mode. The working principle of DISO DC/AC inverter has been used. The control method applied for half load-cycle worked DISO DC/AC inverter has been studied. The control effects of the open-loop proportional control and closed-loop proportional-integral control are compared by using PSIM software. The parameters are adopted in the realistic simulation and experiment test. Moreover, the waveforms, such as voltage of modulation reference signal and output voltage, were given. The simulation and experiment results proved that the half load-cycle worked DISO DC/AC inverter could achieve good performance, gain a line frequency of 50 Hz, and verify the correctness of theoretical analysis.

• Proceedings of the Optical Society of Korea Conference
• /
• 1990.02a
• /
• pp.34-36
• /
• 1990

The flow direction in a glass tube is measured by using a forward scatering dual beam laser Doppler velocimeter with an acousto-optic modulator. We can determine the flow direction by measuring the shifted Doppler frequency which is dependent on the order of modulation of the laser frequency shifting moves only the Doppler signal, enabling complete separation of the Pedestal and Doppler singal.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.327-328
• /
• 2014

This paper presents a pulse density modulation (PDM) technique with a high frequency link for a dual output DC-DC converter. The proposed scheme consists of a fixed frequency AC link and independent PDM controllers for the output regulation, which provides a simple structure and higher efficiency. The simulation and experimental results are provided to show the effectiveness of the proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1993.04b
• /
• pp.97-101
• /
• 1993

In this work, the imaginary part of the inner modulation transfer function of the cutting dynamics is introduced for tool wear monitoring. Time-series method is utilized to construct the generalthree dimensional cutting dynamics whose imaginary part of the inner modulation transfer funcition shows the proportionality to tool wear at the natural frequency of the machine tool dynamics. This modelis reduced to single-input single- output model without altering the proporitonality characteristics to tool wear and implemented to the dual computer system in which one computer performs measurement while the other calculates the imaginary part of the inner modulation transfer function of th cutting dynamics by the batchleast square method. The values of the imaginary part at the natural frequencyof the machine tool structure in the cutting direction are compared to the one calculated during machining with a brand new tool to decide the current stants of the tool. The experiments shows the relevance of the proposed concept.

• Journal of Power Electronics
• /
• v.15 no.2
• /
• pp.309-318
• /
• 2015

This study proposes a dual-output single-stage bridgeless single-ended primary-inductor converter (DOSSBS) that can completely remove the front-end full-bridge alternating current-direct current rectifier to accomplish power factor correction for universal line input. Without the need for bridge diodes, the proposed converter has the advantages of low component count and simple structure, and can thus significantly reduce power loss. DOSSBS has two uncommon output ports to provide different voltage levels to loads, instead of using two separate power factor correctors or multi-stage configurations in a single stage. Therefore, this proposed converter is cost-effective and compact. A magnetically coupled inductor is introduced in DOSSBS to replace two separate inductors to decrease volume and cost. Energy stored in the leakage inductance of the coupled inductor can be completely recycled. In each line cycle, the two active switches in DOSSBS are operated in either high-frequency pulse-width modulation pattern or low-frequency rectifying mode for switching loss reduction. A prototype for dealing with an $85-265V_{rms}$ universal line is designed, analyzed, and built. Practical measurements demonstrate the feasibility and functionality of the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.13 no.6
• /
• pp.453-460
• /
• 2008

This paper proposes a new multi-output LLC resonant converter by using single control IC, which has the tight-regulated dual output voltage without additional power devices and controller. The proposed converter has master and slave outputs, of which regulations are achieved by the PWM(pulse width modulation) and PFM(pulse frequency modulation), respectively. Different from the conventional dual-output LLC resonant converter, the proposed converter has no additional post-regulators like a boost converter. Therefore, it features a low cost, small size, and high efficiency. To confirm the validity and prove the superiority of proposed converter, simulated and experimental results on a 50" FHD PDP power set prototype are presented.

• The Journal of the Acoustical Society of Korea
• /
• v.18 no.5
• /
• pp.52-57
• /
• 1999

It is very important to design of QAM modulator of high spectral efficiency for high speed data transmission. In this paper, typical 16-QAM modulator is designed by modification design of DDFS(direct digital frequency synthesizer). DDFS generates sinusoidal waveform digitally to the frequency setting word. Phase modulation is accuratly made by control of a generated phase increment value and amplitude modulation is accomplished in the D/A converter output by control of amplitude level. For the suppression of harmonics and glitch, dual-structured DDFS is studied to improve the spurious characteristics. P-Spice is used for design and simulation in mixed mode. Also we can get the satisfactory results of designed 16-QAM modulator from the constellation output.