• Journal of electromagnetic engineering and science
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• 제15권2호
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• pp.82-88
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• 2015

The magnetron, a vacuum tube, is currently the usual high-power microwave power source used for microwave heating. However, the oscillating frequency and output power are unstable and noisy due to the low quality of the high-voltage power supply and low Q of the oscillation circuit. A heating system with enhanced reliability and the capability for control of chemical reactions is desired, because microwave absorption efficiency differs greatly depending on the object being heated. Recent studies on microwave high-efficiency power amplifiers have used harmonic processing techniques, such as class-F and inverse class-F. The present study describes a high-efficiency 100 W GaN-HEMT amplifier that uses a harmonic processing technique that shapes the current and voltage waveforms to improve efficiency. The fabricated GaN power amplifier obtained an output power of 50.4 dBm, a drain efficiency of 72.9%, and a power added efficiency (PAE) of 64.0% at 2.45 GHz for continuous wave operation. A prototype microwave heating system was also developed using this GaN power amplifier. Microwaves totaling 400 W are fed from patch antennas mounted on the top and bottom of the microwave chamber. Preliminary heating experiments with this system have just been initiated.

• 전자공학회논문지D
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• 제35D권5호
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• pp.11-17
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• 1998

In this paper, the synthesis procedufe of impedance matching network is presented for broad-band microwave amplifier design, whereby amplifier operating in the octave bandwidth is designed and fabricated in detail. The transfer function of the matching netowrks is synthesized by chebyshev approximation and element values for the networks of specified topology are calculatd for various MILs and ripples. After the transistor is modeled by negative-image device model, the synthesis procedure for matching networks is applied to broad-band amplifier design which has electrical performance of about 12dB gain in 4 to 8GHz range. Experimental results obtained from the fabricated amplifier are shown to approach the electrical performance designed in the given frequency range. Construction of the impedance matching networks by transfer function synthesis is very useful method for the design of broad-band microwave amplifiers.

• 반도체디스플레이기술학회지
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• 제15권4호
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• pp.22-26
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• 2016

In this paper, we measured the efficiency of the receiver for 5.8GHz Microwave Smartphone Charging. We have designed and fabricated 1W and 2W power amplifier, respectively. A 1W power amplifier used a TC3531 power device of TRANSCOM Inc. In addition, a 2W power amplifier using the two TC3531 devices was constructed with divider and combiner. We used the Wilkinson divider theory for divider and combiner. The voltage was measured using the 1W and 2W power amplifier and integrated receivers to the distance of 50cm.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.623-624
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• 2006

In this paper, we introduce the design and fabrication of V-band power amplifier MMIC with excellent gain-flatness for IEEE 802.15.3c WPAN system. The V-band power amplifier was designed using ETRI' $0.12{\mu}m$ PHEMT process. The PHEMT shows a peak transconductance ($G_{m,peak}$) of 500 mS/mm, a threshold voltage of -1.2 V, and a drain saturation current of 49 mA for 2 fingers and $100{\mu}m$ total gate width (2f100) at $V_{ds}$=2 V. The RF characteristics of the PHEMT show a cutoff frequency, $f_T$, of 97 GHz, and a maximum oscillation frequency, $f_{max}$, of 166 GHz. The gains of the each stages of the amplifier were modified to have broadband characteristics of input/output matching for first and fourth stages and get more gains of edge regions of operating frequency range for second and third stages in order to make the gain-flatness of the amplifier excellently for wide band. The performances of the fabricated 60 GHz power amplifier MMIC are operating frequency of $56.25{\sim}62.25\;GHz$, bandwidth of 6 GHz, small signal gain ($S_{21}$) of $16.5{\sim}17.2\;dB$, gain flatness of 0.7 dB, an input reflection coefficient ($S_{11}$) of $-16{\sim}-9\;dB$, output reflection coefficient ($S_{22}$) of $-16{\sim}-4\;dB$ and output power ($P_{out}$) of 13 dBm. The chip size of the amplifier MMIC was $3.7{\times}1.4mm^2$.

• 한국항해항만학회지
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• 제30권5호
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• pp.351-356
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• 2006

본 논문에서는 마이크로파 대역의 주파수를 이용해 고효율 도허티 전력 증폭기를 설계 및 제작하였다. 도허티 전력증폭기는 MRF 281 LDMOS FET를 사용하여 구현하였고, 도허티 전력 증폭기의 성능을 AB급 증폭기만 있을 때와 비교하였다. 측정결과, 구현한 도허티 전력 증폭기는 P1dB 출력전력이 2.3GHz 주파수에서 33.0dBm을 가진다. 또한, 도허티 증폭기는 주파수 $2.3GHz\sim2.4GHz$에서 이득은 11dB, 입력 반사손실 -17.8dB를 얻었다. 설계된 도허티 증폭기는 AB급 증폭기만 있을 때와 비교해서 평균 PAE는 10% 이상 개선됨을 보였고, 설계된 도허티 증폭기의 최대 PAE는 39%를 갖는다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 춘계학술대회 및 창립 30주년 심포지엄(논문집)
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• pp.91-96
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• 2006

본 논문에서는 마이크로파 대역의 주파수를 이용해 고효율 도허티 전력 증폭기를 설계 및 제작하였다. 도허티 전력증폭기는 MRF 281 LDMOS FET를 사용하여 구현하였고, 도허티 전력 증폭기의 성능을 AB급 증폭기만 있을 때와 비교하였다. 측정결과, 구현한 도허티 전력 증폭기는 PldB 출력전력이 2.3GHz 주파수에서 33.0dBm을 가진다. 또한, 도허티 증폭기는 주파수 $2.3GHz{\sim}2.4GHz$에서 이득은 11dB, 입력 반사손실-17.8dB를 보인다. 설계된 도허티 증폭기는 AB급 증폭기만 있을 때와 비교해서 평균 PAE는 10% 이상 개선됨을 보였고, 설계된 도허티 증폭기의 최대 PAE는 39%를 갖는다.

• 한국전자파학회지:전자파기술
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• 제2권2호
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• pp.3-10
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• 1991

GaAs FET초고주파 증폭기의 DC 블럭용으로 사용되는 칩 커페시터 대신 DC블럭 및 임피던스 변환 성질을 가진 DC block/transformer(비대칭 2선 마이크로스트립 선로 및 까지낀 3선 마이크로스트립 선로)를 사용한 초고주파 증폭기의 새로운 구성 방법을 제시하였다. 새로운 구성을 갖는 초고주파 증폭기의 대역 특성은 평탄하며 대역폭이 3.5(BHz)인 광대역 특성을 얻으 수 있었다. 초고주파 증폭기에 사용된 깍지낀 3선 마이크로스트리 결합 선로는 DC블럭 기능과 함께 임피던스 정합 역할을 할 수 있는 큰 장점을 가지고 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1054-1057
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• 2002

The design and fabrication of Q-band 3-stage monolithic microwave integrated circuit(MMIC) amplifier for WLAN are presented using 0.2$\square$ AIGaAs/lnGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT). In each stage of the MMIC, a negative feedback is used for both broadband and good stability. The measurement results are achieved as an input return loss under -4dB, an output return loss under -10dB, a gain of 14dB, and a PldB of 17dBm at Q-band(36～44GHz). These results closely match with design results. The chip size is 2.8${\times}$1.3mm$^2$. This MMIC amplifier will be used as the unit cell to develop millimeter-wave transmitters for use in wideband wireless LAN systems.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.110-113
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• 1998

An analysis of the relationship between a linear amplifier chain and an analog-to-digital converter(ADC) in a digital microwave widevand receiver, with respect to sensitivity and dynamic range issues, is presented. The effects of gain, third-order intermodulation products and ADC characteristics on the performance of the receiver are illustrated and design criteria for the linear amplifier chain given a specified ADC are developed. A computer program is used to calculate theretical receiver performance based on gain and third-order intermodulation product selections. Simulated results are also presented and compared with theoretical values.

• 대한전자공학회논문지
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• 제14권5호
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• pp.7-14
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• 1977

주로 TWT로 사용되어 오던 2GHz 대 고출력증식기를 근래 개발되어 시판되기 시작한 microwave bipolar transistor를 사용하여 설계 제작하였다. 특히 고출력을 얻을 목적으로 balanced amplifier로 구성하였으며 microstripline을 사용해서 우수한 impedance정합효과를 얻었다. RF출력의 divider 및 combiner로서는 제작상의 편의를 감안해서 stripline directional coupler방식을 채택했으며 이것은 quadrature hybrid coupler로서 좋은 동작특성을 보였다. 직접 실용화를 감안해서 설계, 시작된 본 마이크로파 트랜지스터 증폭기는 측정결과 RF출력 14watt, 이득 14dB, 편파수대역폭 180MHz, 효율 40%의 우수한 종합특성을 얻었다.