• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.136-141
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• 2016

A phase-locked loop(PLL) with effectively increased capacitance by current modulator has been proposed. In this paper, the effective capacitance of loop filter is increased by using current modulator and it results in 1/10 reduction of capacitance in loop filter. It has been designed with a 1.8V $0.18{\mu}m$ CMOS process. The simulation results show that the proposed PLL has the same phase noise characteristic and locking time of conventional PLL.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.698-701
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• 2016

A phase-locked loop(PLL) with effectively increased capacitance by current modulator has been proposed. In this paper, the effective capacitance of loop filter is increased by using current modulator and it results in 1/10 reduction of capacitance in loop filter. It has been designed with a 1.8V $0.18{\mu}m$ CMOS process. The simulation results show that the proposed PLL has the same phase noise characteristic and locking time of conventional PLL.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1800-1802
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• 1998

The Pohang Light Source (PLS) is a third generation 2 GeV synchrotron machine. An injection kicker modulator is positioned in the PLS storage ring tunnel. The kicker modulator is driving four kicker magnets simultaneously. The kicker magnets produce magnetic field to deflect the stored beam orbit in the storage ring closer to the injected beam from the PLS beam transfer line. The injected beam then falls into the storage ring beam dynamic aperture. The current kicker modulator was upgraded and installed on August 1995. Since then, the kicker modulator has shown very reliable and stable performance. The kicker modulator specifications are ${\sim}6.0{\mu}s$ full width, ${\sim}24$ kA peak current, and 10 Hz repetition rate. Output current waveform is a half sinusoid. Two thyratron switches(EEV CX-1536AX) are used in the kicker modulator. Total accumulated thyratron heater run hour is about 15,000 hours as of May 1998. Measurement result of spatial magnetic field distribution in the kicker magnet shows good uniformity.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.3
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• pp.120-126
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• 2005

The Korean Superconducting Tokamak Advanced Research (KSTAR) tokamak device is being constructed to perform long-pulse, high-beta, advanced tokamak fusion physics experiments. The long-pulse operation requires the non-inductive current drive system such as the Lower-Hybrid Current Drive (LHCD) system. The LHCD system drives the non-inductive plasma current by means of C-band RF with 2-MW CW power and 5-GHz frequency. For the LHCD test experiments, an RF test system is developed. It is composed of a 5-GHz, 1.5-MW pulsed magnetron and a compact pulse modulator with $4\;{\mu}s$ of pulse width. The pulse modulator provides the maximum output voltage of 45 kV and the maximum current of 90 A. It is composed of 7 stages of Pulse Forming Network (PFN), a thyratron tube (E2V, CX1191D), and a pulse transformer with 1:4 step-up ratio. In this paper, the detailed design and the performance test of the pulse modulator are presented.

• Current Optics and Photonics
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• v.8 no.4
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• pp.399-405
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• 2024

In this paper, an optical modulator based on monolayer graphene and triple-layer black phosphorus (BP) heterojunction in the optical communication band range is designed. The influences of geometric parameters, chemical potential, BP orientation and dispersion on the fundamental mode of this modulator were determined in detail by the finite-difference time-domain (FDTD) method. Using appropriate geometric parameter settings, the extinction ratio of this proposed modulator is 0.166 dB, while the modulator with a working length of 3 ㎛ can realize a 0.498 dB modulation depth. The 3-dB bandwidth of this modulator could achieve up to 2.65 GHz with 27.23 fJ/bit energy consumption. The extinction ratio and bandwidth of the proposed modulator increased by 66% and 120.83%, respectively, compared to the monolayer graphene-based ridge-type waveguide modulator. Energy consumption was reduced by 97.28%, compared to a double-layer graphene-based modulator.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.421-422
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• 2017

The kicker modulator was upgraded and installed in 1995. The PLS-II injection kicker modulator is configured with series resonant circuit. A total of four kicker magnets are used to distribute the normal storage ring beam orbit toward the septum magnet wall. Only one kicker modulator is used to drive the four kicker magnets. It is not adjust the current magnitude and timing of magnets. During the kicking, the beam has oscillation of 2 mm horizontal direction and $200{\mu}m$ vertical direction in present injector system. Our goals is to decrease the oscillation less than $300{\mu}m$. To give balanced current for all four magnets and to have precise timing between magnet current, we have plan to divide kicker power supply into four individual power supply. In this paper, the design of new individual kicker power supply and Fabrication of the new injector system is presented.

• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.227-231
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• 2011

An external optical modulation using absorption s in a Fabry-Perot laser diode (FP-LD), has been proposed and experimentally demonstrated for multicasting in a WDM-PON. The center wavelengths of absorption s in an FP-LD move to short-wavelength rapidly by only a small current (~1 mA) injection. If the current injection is stopped, the s move back to the original position. Such a movement of the s can make the FP-LD act as an external optical modulator, which is found to modulate at a maximum modulation speed of 800 Mbps or more. For a multicasting transmitter in a WDM-PON, the proposed modulator can be cost-effectively applied to a multi-wavelength laser source with the same periodicity of the longitudinal mode. Instead of the multi-wavelength laser source, tunable-LDs are used for experiments. The 32 channel multicasting system with the proposed modulator has been demonstrated, showing power penalties of 1.53~4.15 dB at a bit error rate of $10^{-9}$ with extinction ratios better than 14.5 dB at 622 Mbps.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.307-308
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• 2019

The Pohang Light Source (PLS) - II is a 3 GeV third-generation synchrotron radiation facility. To inject electron beam from LINAC, a kicker modulator system and kicker magnets are installed in the PLS-II storage ring tunnel. The injected beam then falls into the storage ring beam dynamic aperture. This paper describes the design and implementation of the solid-state kicker modulator for PLS-II. The solid-state kicker modulator is consisted of high voltage solid state switch stacks. the technical considerations of the solid-state switch stacking for kicker modulator is discussed. The achieved capability of the solid-state kicker modulator demonstrates that is fulfills the design requirement of providing half-sine pulsed current of 10kA (peak), 6us (Base-width), with jitter < 2ns (Standard deviation). simulation and experimental results are presented to demonstrate the performance of the solid-state kicker modulator.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.341-346
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• 2017

In this paper, we present a 60 GHz on-off keying (OOK) modulator in a 90 nm CMOS. The modulator employs a current-reuse technique and a switching modulation for low DC power dissipation, high on/off isolation, and high data rate. The measured gain of the modulator, on/off isolation, and output 1-dB compression point is 9.1 dB, 24.3 dB, and 5.1 dBm, respectively, at 60 GHz. The modulator consumes power consumption of 18 mW, and is capable of handling data rates of 8 Gb/s at bit error rate of less than $10^{-6}$ for $231^{-1}$ PRBS over a distance of 10-cm with an OOK receiver module.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.98-100
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• 2018

This paper describes design of the 40-kV, 300-A solid-state pulsed power modulator for environmental applications. The modulator has been modified based on a solid-state pulsed power modulator with 150-A current capacity. To improve the pulsed power modulator, the discharge IGBT was changed. In addition, the gate driver was tuned according to the characteristics of the switch. Finally, experimental results proved the reliability of the modified solid-state pulsed power modulator.