• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.4
• /
• pp.49-55
• /
• 2010

In this paper, we propose the symbol decision method considering the non-uniformity in color space and analyze the BER performance of modulation scheme based on color space, comparing with the conventional WDM scheme based on light intensity. Through numerical simulation, we show the BER performance superiority under the condition of AWGN and common mode noise.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.390-391
• /
• 2018

본 논문은 직류단 전원을 공유하는 복수의 인버터로 구성된 시스템에서 EMI 저감을 위한 연동제어 PWM 생성 기법을 제안한다. PWM 제어에 의한 스위칭시 전력단 중성점에서 커먼모드 전압이 생성되고, 기생 캐패시터를 통해 전원라인으로 유입되어 EMI 노이즈가 발생된다. 복수의 인버터 시스템에서도 동일한 현상이 나타나고, 이로인한 불특정한 커먼모드 전류가 발생한다. 본 논문에서는 2개의 인버터를 PWM 시점의 동기제어를 통해 커먼모드 노이즈를 상쇄하고자한다. 제안한 제어 기법을 검증하기 위하여 시뮬레이션으로 분석하며, 간이 실험 통해 검증한다.

• Proceedings of the KIEE Conference
• /
• 1993.07a
• /
• pp.479-482
• /
• 1993

A fully balanced differential amplifier can achieve high-gain wide-bandwidth characteristics. And also, Offset PSRR, CMRR and Noise performance of that are excellent, but these merits can be achieved only when the architecture holds fully balanced. Commonly, the fully balanced differential amplifier has a common mode feedback(CMFB) circuit in order to maintain the balance. This paper presents improved characteristics of the CMFB circuit and designs the wide-bandwidth CMOS Op-amp. The unity gain bandwidth of this Op-amp is 50MHz with the load capacitor 2pF, and the value of phase margin is $85^{\circ}$.

• Journal of Sensor Science and Technology
• /
• v.23 no.1
• /
• pp.7-14
• /
• 2014

Noncontact electrocardiogram (ECG) measurement using capacitive-coupled technique is a very reliable long-term noninvasive health-care remote monitoring system. It can be used continuously without interrupting the daily activities of the user and is one of the most promising developments in health-care technology. However, ECG signal is a very small electric signal. A robust system is needed to separate the clean ECG signal from noise in the measurement environment. Noise may come from many sources around the system, for example, bad contact between the sensor and body, common-mode electrical noise, movement artifacts, and triboelectric effect. Thus, in this paper, the extended Kalman filter (EKF) is applied to denoise a real-time ECG signal in capacitive-coupled sensors. The ECG signal becomes highly stable and noise-free by combining the common analog signal processing and the digital EKF in the processing step. Furthermore, to achieve ubiquitous monitoring, android-based application is developed to process the heart rate in a realtime ECG measurement.

• ETRI Journal
• /
• v.27 no.5
• /
• pp.473-483
• /
• 2005

In this paper, we propose two LC voltage-controlled oscillators (VCOs) that improve both phase noise and tuning range. With both 1/f induced low-frequency noise and low-frequency thermal noise around DC or around harmonics suppressed significantly by the employment of a current-current negative feedback (CCNF) loop, the phase noise in the CCNF LC VCO has been improved by about 10 dB at 6 MHz offset compared to the conventional LC VCO. The phase noise of the CCNF VCO was measured as -112 dBc/Hz at 6 MHz offset from 5.5 GHz carrier frequency. Also, we present a bandwidth-enhanced LC VCO whose tuning range has been increased about 250 % by connecting the varactor to the bases of the cross-coupled pair. The phase noise of the bandwidth-enhanced LC-tank VCO has been improved by about 6 dB at 6 MHz offset compared to the conventional LC VCO. The phase noise reduction has been achieved because the DC-decoupling capacitor Cc prevents the output common-mode level from modulating the varactor bias point, and the signal power increases in the LC-tank resonator. The bandwidth-enhanced LC VCO represents a 12 % bandwidth and phase noise of -108 dBc/Hz at 6 MHz offset.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.1 s.92
• /
• pp.56-65
• /
• 2005

We proposed the Power-line EMI filter for vehicle-shelter which have attenuation performance of 100 dB from 10kHz to 1 GHz. The inductor and capacitor for EMI filter design was charactenzed using circuit simulator and then, we experimentally verified 100 dB attenuation for the conducted emission noise through power line. This results will be used for the application systems of protection weapons against EMI attacks as well as vehicle-shelter.

• Journal of Power Electronics
• /
• v.19 no.1
• /
• pp.278-287
• /
• 2019

In this study, a zero-crossing spike current issue in a totem-pole bridgeless power factor correction (PFC) converter is comprehensively investigated for the first time. Spike current occurs when input voltage crosses zero, becomes a noise source, and causes severe common mode emission issues. A generation mechanism for electromagnetic interference (EMI) is presented to investigate the EMI problem caused by zero-crossing issue, and a noise spectrum due to this issue is predicted by a theoretical analysis based on the Fourier coefficient of an approximate spike current waveform. Furthermore, a noise reduction method is proposed and then improved to reduce the spike current. Experimental measurements are implemented on a GaN-based totem-pole bridgeless PFC converter, and the spike current can be effectively suppressed through the proposed method. Furthermore, the noise spectrums measured without and with the reduced zero-crossing spike current are compared. Experimental results validate the analysis of the noise spectrum caused by the zero-crossing spike current issue.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.963-966
• /
• 2005

Model updating method is known to the area to correct finite element models by the results of the experimental modal analysis. Most common methods in model updating depend on a parametric model of the structure. In this case, the number of parameters is normally smaller than that of modal data obtained from an experiment. In order to overcome this limitation, many researchers are trying to get modal data as many as possible to date. 1 want to name this method multiple modified-system generation method. These Methods consist of direct system modification method and feedback controller method. The direct system modification Is to add a mass or stiffness on the original structure or perturb the boundary conditions. The feedback controller method is to make the closed food system with sensor and actuator so as to get the closed loop modal data. In this paper, we need to focus on the feedback controller method because of its simplicity. Several methods related the feedback controller methods are virtual passive controller (VPC) sensitivity enhancement controller (SEC) and mode decoupling controller (MDC). Among them, we will apply MDC to the model updating problem. MDC has various advantages compared with other controllers, such as VPC and SEC. To begin with, only the target mode can be changed without changing modal property of non-target modes. In addition, it is possible to fix any modes if the number of sensors is equal to that of the system modes. Finally, the required control power to achieve desired change of target mode is always lower than those of other methods such as VPC. However, MDC can make the closed loop system unstable when using incomplete modal data. So we need to take action to avoid undesirable instability from incomplete modal data. In this paper, we address the method to design the unique and robust MDD obtained from incomplete modal data. The associated simulation will be Incorporated to demonstrate the usefulness of this method.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2002.11a
• /
• pp.111-116
• /
• 2002

With the proliferation of nonlinear loads such as personal computers in an educational office building, high neutral harmonic currents have been observed. High neutral currents in three-phase four-wire distribution power systems can cause overloaded neutral conductors, overloaded transformers, voltage distortion, common mode noise, and malfuntion of protective equipment. On-site measurements of harmonic currents and voltages were made and the corresponding equivalent circuits was developed. The circuit model under study was simulated numerically and graphically through the use of the software MATLAB.

• Journal of Korea Society of Industrial Information Systems
• /
• v.18 no.5
• /
• pp.9-14
• /
• 2013

This paper is designed frequency multiplier with low phase noise using DLL technique. The VCDL is designed using a differential structure to reduce common-mode noise. The proposed frequency multiplier is fabricated in a 65nm, 1.2V TSMC CMOS process, and the operating frequency range from 10MHz to 24MHz was measured. The SSB phase noise is measured to be -125dBc/Hz at 1MHz from 38.4MHz carrier. A total area of $0.032mm^2$were consumed in the chip, including the output buffer. Total current is 1.8mA at 1.2V supply voltage.