• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.515-515
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• 2013

RF는 사이클로트론에서 빔을 원하는 에너지로 가속하기위해 쓰인다. MC50 사이클로트론에는 두 개의 DEE가 있고 각각 독립된 LLRF모듈과 증폭기를 통해 제어된다. 주요 제어변수는 DEE1,2의 Voltage와 양단간의 Phase인데 이는 RF Generator에서 특정 주파수로 발생된 RF 시그널의 Amplitude와 Phase를 RF Modulator에서 변조하므로 제어되어진다. 지금 현재의 Modulator는 오래되어 DEE Voltage의 컨트롤이 잘 이루어지지 않고 있고 가끔 연결부위에서 문제를 보여 새 Modulator를 제작하게 되었다. 기존의 LLRF는 아날로그 방식인데 아날로그 방식은 외부제어가 어렵고 확장이 쉽지 않아 디지털 제어방식으로 설계하였다. 새 LLRF는 저속처리부와 고속처리부로 두 부분으로 구성하였다. Final amplifier와 cavity의 상태를 체크하는 저속처리부는 PLC로 RF 시그널의 Amplitude와 Phase를 제어하는 고속처리부는 FPGA로 제어할 계획이다.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.6
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• pp.653-657
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• 2015

A new paired gate-source voltage RF capacitance-voltage (C-V) method of extracting the effective channel length and parasitic capacitance using the intersection between two closely spaced linear regression lines of the gate capacitance versus gate length measured from S-parameters is proposed to remove errors from conventional C-V methods. Physically verified results are obtained at the gate-source voltage range where the slope of the gate capacitance versus gate-source voltage is maximized in the inversion region. The accuracy of this method is demonstrated by finding extracted value corresponding to the metallurgical channel length.

• Journal of Semiconductor Engineering
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• v.3 no.1
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• pp.154-160
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• 2022

In this paper, we design a DC-DC boost converter with RF noise immunity to supply a stable positive output voltage for OLED displays. For RF noise immunity, an input voltage variation reduction circuit (IVVRC) is adopted to ensure display quality by reducing the undershoot and overshoot of output voltage. The boost converter for a positive voltage Vpos operates in the SPWM-PWM dual mode and has a dead-time controller using a dead-time detector, resulting in increased power efficiency. A chip was fabricated using a 0.18 um BCDMOS process. Measurement results show that power efficiency is 30% ~ 76% for load current range from 1 mA to 100 mA. The boost converter with the IVVRC has an overshoot of 6 mV and undershoot of 4 mV compared to a boost converter without that circuit with 18 mV and 20 mV, respectively.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.191-196
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• 2017

Microwave wireless power transmission (MWPT) is a promising technique for low and medium power applications such as wireless charging for sensor network or for biomedical chips in case with long ranges or in dispersive media such. A key factor of the MWPT technique is its efficiency, which includes the wireless power transmission efficiency and the radio frequency (RF) to direct current (DC) voltage efficiency of RF-DC converter (which transforms RF energy to DC supply voltage). The main problem in designing an RF-DC converter is the nonlinear characteristic of Schottky diodes; this characteristic causes low efficiency, higher harmonics frequency and a change in the input impedance value when the RF input power changes. In this paper, rather than using harmonic termination techniques of class E or class F power amplifiers, which are usually used to improve the efficiency of RF-DC converters, we propose a new method called "optimal input impedance" to enhance the performance of our design. The results of simulations and measurements are presented in this paper along with a discussion of our design concerning its practical applications.

• Transactions on Electrical and Electronic Materials
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• v.14 no.5
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• pp.225-230
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• 2013

This paper presents a novel shunt radio frequency microelectromechanical system switch on a quartz substrate with stiff ribs around the membrane. The buckling effects in the switch membrane and stiction problem are the primary concerns with RF MEMS switches. These effects can be reduced by the proposed design approach due to the stiffness of the ribs around the membrane. A lower mass of the beam and a reduction in the squeeze film damping is achieved due to the slots and holes in the membrane, which further aid in attaining high switching speeds. The proposed switch is optimized to operate in the k-band, which results in a high isolation of -40 dB and low insertion loss of -0.047 dB at 21 GHz, with a low actuation voltage of only 14.6 V needed for the operation the switch. The membrane does not bend with this membrane design approach. Finite element modeling is used to analyze the stress and pull-in voltage.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.185-189
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• 2004

In this paper, designed a diode detector and a log chip detector for mobile communication, and its application is proposed by compared results. In practice, fabricated a diode detector have showed detection voltage of $0{\sim}0.7V$ to RF input power of $-40dBm{\sim}-10dBm$, therefore it has suitable characteristic for small variable signal detection. And a log chip detector have showed wide dynamic range of 65dB, and $1.5{\sim}4.5V$ detection voltage to RF input power of $-65dBm{\sim}0dBm$. therefore we have found that it suit peak power measurement because it had insensible output detection voltage.

• Journal of the Korean institute of surface engineering
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• v.52 no.6
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• pp.342-349
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• 2019

Titanium nitride(TiN) thin films have been deposited on PEN(Polyethylene naphthalate) substrate by reactive RF(13.56 MHz) magnetron sputtering in a 25% N₂/Ar mixed gas atmosphere. The pulsed DC bias voltage of -50V on substrates was applied with a frequency of 350 kHz, and duty ratio of 40%(1.1 ㎲). The effects of pulsed DC substrate bias voltage on the crystallinity, color, electrical properties of TiN_x films have been investigated using XRD, SEM, XPS and measurement of the electrical properties such as electrical conductivity, carrier concentration, mobility. The deposition rates of TiN_x films was decreased with application of the pulsed DC substrate bias voltage. The TiN_x films deposited without and with pulsed bias of -50V to substrate exhibits gray and gold colors, respectively. XPS depth profiling revealed that the introduction of the substrate bias voltage resulted in decreasing oxygen concentration in TiN_x films, and increasing the electrical conductivities, carrier concentration, and mobility to about 10 times, 5 times, and 2 times degree, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.1038-1043
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• 2003

A capacitive-coupled configuration MEMS switch is designed and fabricated, and its characteristics are measured. Low actuation voltage has been achieved by means of small distance between signal line and membrane. Minimum actuation voltage is about 11V. Isolation is around 40dB and insertion loss is about 0.2dB at 2GHz.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1920-1923
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• 1991

An online RF power measurement is needed for the full-bridged MOS-FET RF power inverter because the output current and/or voltage waveform is other than sinusoidal. In order to satisfy the requirement, the online measurement of the output power of this type of RF power inverter by the use of the PC-98 personal computer has been presented. The current and voltage waveforms are sensed by the digital oscilloscope probes so as to obtain the instantaeous power and they are entered into the PC98 personal computer so as to average the instantaneous powers. The RF power of up to 1 kw at 1 MHz measured for the power inverter at the output transformer. This method was confirmed to be applied to evaluate the load resistance change with temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.8
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• pp.622-628
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• 2001

We developed 1- and 2-dimensional fluid model for the analysis of a capacitively coupled Ar RF(Radio Frequency) glow discharge. This discharge is in pure Ar gas at the pressure 100[mTorr], frequency 13.56[MHz] and voltage amplitude 120[V}. This model is based on the equations of continuity and electron energy conservation coupled with Poison equation. 2-dimensional model is simulated on the condition of GEC(Gaseous Electronic Conference cell). The geometry of the discharge chamber and the electrodes used in the model is cylindrically simmetric; tow cylinders for the electrodes are surrounded by the grounded chamber. It is shown that 1-dimensional model is very useful on the understanding of RF glow discharge property and of the movement of charged particles. 2-dimensional model predicts off-axis maximum structure as in the experiments and has the results in qualitatively and quantitatively good agreement with the experiments. Effects of dc self-bias voltage, guard ring and reactor geometry is discussed.