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13.56 ㎒, 300 Watt 고효율 Class E 전력 송신기 설계
전정배(Jeongbae Jeon),서민철(Mincheol Seo),김형철(Hyungchul Kim),김민수(Minsu Kim),정인오(Inoh Jung),최진성(Jinsung Choi),양영구(Youngoo Yang) 한국전자파학회 2011 한국전자파학회논문지 Vol.22 No.8
본 논문에서는 220 V의 AC 전원을 공급받아 13.56 ㎒의 RF 신호를 출력하는 고효율, 고출력 Class E 전력송신기를 설계하였다. 송신기는 AC-DC 변환기와 class E 전력 증폭기로 구성된다. 설계된 AC-DC 변환기는 220V/60 ㎐의 가정용 전원을 공급 받아서 약 290 V의 DC 전압을 출력한다. 이때, AC-DC 변환기는 98.03 %의 매우 높은 변환 효율을 가진다. 변환 효율을 최대로 하기 위하여 별도의 DC-DC 변환기를 사용하지 않고, AC-DC 변환기의 출력 전압을 주 전력 증폭기의 드레인 바이어스 전압으로 사용하였다. 또한, class E 전력 증폭기의 전력손실을 최소화하기 위해 high-Q 인덕터를 제작하였다. 측정 결과, 13.56 ㎒에서 동작하는 class E 전력 증폭기는 최대 출력 전력 323.6 Watt에서 84.2 %의 PAE(Power-Added Efficiency)를 가진다. AC-DC 변환기를 포함한 class E 전력 송신기는 323.6 Watt에서 82.87 %의 매우 높은 효율 특성을 나타낸다. This paper presents a design of high-efficiency and high-power class E power transmitter. The transmitter is composed of 300 Watt class E power amplifier and AC-DC converter. The AC-DC converter converts 220 V and 60 ㎐ AC to a 290 V DC. The generated DC voltage is directly applied to a bias of the class E power amplifier. Because the converter does not have DC-DC converter unit, it has very high conversion efficiency of about 98.03 %. To minimize the loss at the output of the power amplifier, high-Q inductor was implemented and deployed to the output resonant circuit. As a result, the 13.56 ㎒ class E power amplifier has a high power-added efficiency of 84.2 % at the peak output power of 323.6 W. The overall efficiency of class E power transmitter, including the AC-DC converter, is as high as 82.87 %.
Ultrabroadband Linear Power Amplifier Using a Frequency-Selective Analog Predistorter
Mincheol Seo,Kyungwon Kim,Minsu Kim,Hyungchul Kim,Jeongbae Jeon,Myung-Kyu Park,Hyojoon Lim,Youngoo Yang IEEE 2011 IEEE Transactions on Circuits and Systems II: Expr Vol.58 No.5
<P>This brief presents an ultrabroadband (2- to 600-MHz band) linear power amplifier using a compact frequency-selective analog predistorter, which includes a capacitor having an optimized capacitance and a biased Schottky diode connected in series. It is shunted at the input of the main amplifier and has a frequency-selective third-order intermodulation generation capability using its optimized capacitance. A two-stage push-pull power amplifier, which has an ultrabroadband operation range from 2 to 600 MHz, was implemented and linearized using the proposed analog predistorter. It exhibited high 1-dB compression point (P1 dB) and power-added efficiency characteristics of over 43 dBm and 32% at each P1 dB for the entire operating band, respectively. At an average output power level of 36 dBm for the two-tone signal input, which has a tone spacing of 1 MHz, its third-order intermodulation distortion over the entire band is no higher than -39.1 dBc after linearization, as compared with -34.2 dBc before linearization.</P>
Dynamic Bias Switching을 이용한 3.5 ㎓ Balanced Power Amplifier의 효율 개선
서민철(Mincheol Seo),김경원(Kyung-Won Kim),김민수(Min-Su Kim),김형철(Hyung-Chul Kim),전정배(Jeongbae Jeon),양영구(Youngoo Yang) 한국전자파학회 2010 한국전자파학회논문지 Vol.21 No.8
본 논문에서는 3.5 ㎓에 설계된 balanced amplifier에 DBS(Dynamic Bias Switching)를 적용하여 평균 전력에서 효율을 개선하였다. DBS는 입력 신호의 포락선 크기에 따라 전력 증폭기에 두 단계의 드레인 전압을 인가하여 효율을 개선하는 기술로써 balanced amplifier에 DBS를 적용하기 위해서 동일하게 구성된 DBS 회로를 각 단에 설치하여 실제 제작하였다. 20 ㎒ 대역폭과 8.5 ㏈의 PAR(Peak to Average Ratio)을 갖는 OFDM 신호를 사용하여 측정한 결과, 28 V 단일 드레인 전압을 사용했을 때보다 42.5 dBm에서 6 %의 PAE 개선을 나타냈다. This paper presents an efficiency enhancement for the balanced power amplifier using DBS(Dynamic Bias Switching) method which dynamically provides the power amplifier with two bias voltage levels according to the input envelope signal. In order to apply the dynamic biases to each side of the balanced power amplifier, two switching stages are adopted. Using an OFDM signal with a bandwidth of 20 ㎒ and a PAR(Peak to Average Ratio) of 8.5 ㏈, 6 % of PAE(Power-Added Efficiency) is improved at an output power of 42.5 dBm.
최중근,김정배,서정원,이명호 서울산업대학교 2005 논문집 Vol.54 No.1
Characteristics of discharge pressure ripples in vane compressor has been investigated experimentally under the various circumstances, and relations between pressure rise waveform and pressure ripple waveform has been analysed. Discharge pressure ripples in compression chamber of vane compressor produced for this experiments have been measured in case of different average discharge pressure as 3, 5, 7bar and also in case of different rotor rotational velocity as 735, 1060, 1750rpm. It has been observed that the magnitude of discharge pressure ripple has tendency to increase with lower average discharge pressure, and also tendency to increase with higher rotation speed of rotor. Under the condition of constant rotation velocity of rotor and variation of average discharge pressure, start and termination rotation angles of pressure rising process have been constant without concerning variation of average discharge pressure, and gradient of pressure rising with variation of average discharge pressure has been different tendency.