• Journal of electromagnetic engineering and science
• /
• v.4 no.3
• /
• pp.107-112
• /
• 2004

In this paper, the phase noise of 900 MHz VCO is improved using modified strip line square ring resonator. In order to demonstrate the phase noise improvement of the proposed VCO, the same circuit was manufactured using shorted-circuit resonator. In condition of the same bias current, the phase noise of the proposed VCO with modified square ring resonator is suppressed by 7 dB as - 103 dBc/Hz at 100 kHz offset compared to the conventional VCO with short-circuit resonator. From the proposed VCO, we achieved output power of - 4.8 dBm, harmonics suppression of 16 dB, and tuning bandwidth of 100 MHz. The proposed VCO consumed 5 mA at 3 V, and its size is 1.2 cm ${\times}$ 1.0 cm.

• Journal of electromagnetic engineering and science
• /
• v.8 no.3
• /
• pp.114-118
• /
• 2008

Direct-conversion RF front-end for 5-GHz WLAN is implemented in $0.18-{\mu}m$ CMOS technology. The front-end consists of a low noise amplifier, and low flicker noise down-conversion mixers. For the mixer, an inductor is included to resonate out parasitic tail capacitances in the transconductance stage at the operating frequency, thereby improves the flicker noise performance of the mixer, and the overall noise performance of the front-end. The receiver RF front-end has 6.5 dB noise figure, - 13 dBm input IP3, and voltage conversion gain of 20 dB with the power consumption of 30 mW.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.7
• /
• pp.1336-1341
• /
• 2009

In this paper, an EMI reduction effects using an EMC chamber is described and reduction methods is proposed. In the case of general electronic components a working frequency is low. But in this paper the vehicle cluster works 75MHz in the main clock frequency, becoming weak by noise because of being attached in TFT LCD. As the outer case installed in the vehicle is made up of plastic materials, the noise is radiated if not protecting noise in the PCB itself. Therefore, This paper will explain the theoretical basis and propriety with respect to the discussion and need about the guide for PCB design considering EMC, through the reduction of PCB noise.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2000.11a
• /
• pp.216-219
• /
• 2000

A Ka Band 3-stage MMIC (Monolithic Microwave Integrated Circuits) LNA(Low Noise Amplifiers) has been designed. The MMIC LNA consists of two single-ended type amplication stapes and one balanced type amplication stage to satisfy noise figure characteristics and high gain and amplitude linearity. The 0.15um pHEMT has been used to provide a ultra low noise figure and high gain amplification. Series and Shunt feedback circuits were inserted to ensure high stability over frequency range of DC to 80 GHz. The size of designed MMIC LNA is 3100mm ${\times}$ 2400um(7.44$\textrm{mm}^2$). The on wafer measured noise figure of the MMIC LNA is less than 2.0 dB over frequency range of 22 GHz to 30 GHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2002.11a
• /
• pp.209-212
• /
• 2002

본 논문에서는 위성방송 수신용 광대역 저잡음 증폭기를 설계 및 구현하였다. 전산모의 실험용 소프트웨어를 사용하여 저잡음 증폭기를 설계하였고, 제작된 저잡음 증폭기의 전기적 특성을 네트워크 분석기와 Noise Figure 분석기를 사용하여 측정하였다. LNA단의 Noise Figure에 중점을 두고 샘플을 제작하여 측정한 길과 전산모의실험에서 나온 데이터는 0.46㏈이하였고 전체 시스템에서 측정된 Noise figure는 0.6㏈정도의 좋은 길과를 나타내었지만, 반면에 이득과 반사손실의 결과가 약간 떨어짐을 보였다 위성 인터넷 등 위성을 이용하는 통신 인구의 급격한 증가와 더불어 구현된 저잡음 증폭기를 사용한 LNB(Low Noise Block down converter)가 널리 응용될 것으로 기대된다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1026-1029
• /
• 2003

There are always some errors in force sensing of multi-axis force sensors that aggravate sensor performance. Error sources may be classified mainly in two groups. One is structural error due to inaccuracy of sensor body, and the other is error due to noise signals existing in the sensed information. This paper presents a brief review about the principle of multi-axis force sensors, and then a method that can reduce the effect of noise signals. The method is to read digital signals in computer instead of analog voltage signals. We can eliminate the bad effect of electromagnetic waves emitted from computer and of 60 Hz noise emitted from AC source by the proposed method. The proposed method is investigated through experimental demonstration. The experimental results show the proposed method improves the sensor performance significantly.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.2
• /
• pp.207-213
• /
• 1997

Measurements of the RF(Radio Frequency) noise spectrum from 30 MHz to 18 GHz have been conducted at 21 urban areas in Korea in 1994 and 1995. Statistical analysis of the data measured seasonally, day and night, at each different point has been performed. The results of the computer analysis on APD, NAD, and ACR[1] using GUI(Graphical User Interface) program show that the radio noise environments vary little in spring, summer, and winter, while the noise level increases a little in fall. In addition, the noise level of the night time shows a little higher than that of the day time.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.3
• /
• pp.356-363
• /
• 2011

Vibrations and noise in electrical machines are directly related to the characteristics of the radial forces on one hand, and mechanical behavior on the other [1, 4]. The characteristics of these forces depend on the air gap flux density, which is also influenced by other factors, such as stator slots and poles, saturation level, winding type, and certain faults. The aim of this work is to investigate the effect of eccentricity and demagnetization faults on electromagnetic noise generated by the external surface of Permanent Magnet Synchronous Machine [PMSM]. For this purpose, an analytical electromagnetic vibroacoustic model is developed. The results confirm the effect of eccentricity and demagnetization fault in generating some low modes radial forces.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.4
• /
• pp.336-342
• /
• 2003

In this paper, a new differential detector is introduced, in which a solar cell is used to reduce the low frequency interference from environmental optical noise. The solar cell also supplies electrical power to the detector circuit using the optical noise power. The DC voltage from the solar cell is used as a power supply to the detector, and the AC voltage is used to reduce the optical noise in a photodiode with the differential detection method. The signal to noise ratio was improved by about 20 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.8
• /
• pp.891-897
• /
• 2003

In this paper, a circular orthogonal polarizer is newly fabricated and used in a differential detector to reduce the optical noise in a wireless optical interconnection. The orthogonal polarizer is composed of two semicircular polarizers whose transmission axes are orthogonal each other, The orthogonal polarizer is driven by a motor and matched to the signal polarization in order to reduce the optical noise interference. The noise power was reduced by about 20 dB using a differential detector with the orthogonal polarizer.