• 한국항해항만학회지
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• 제26권3호
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• pp.295-302
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• 2002

현재의 디지털 통신시스템은 매우 다양한 디지털 변조방식을 채택하고 있다. 이러한 통신시스템에서는 인접채널에 대한 간섭을 최대한 줄이기 위해서 필연적으로 선형 전력증폭기를 요한다. 선형 전력증폭기는 매우 다양한데 그 중에서 전방궤환 전력증폭기는 구조상 광대역이면서 선형화 정도가 매우 우수하다. 전방궤환 전력중폭기에 사용되는 지연선로의 손실로 인하여 전체효율이 감소한다. 본 논문에서는 이러한 지연선로를 손실이 매우 작은 지연필터를 사용함으로써 효율과 선형성을 동시에 개선하였다. 측정된 결과 ACLR이 약 17.43dB 개선되었으며 이것은 지연필터를 사용함으로써 2.54dB 더 개선되었음을 나타낸다.

• 한국산학기술학회논문지
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• 제10권8호
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• pp.1817-1823
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• 2009

본 논문에서는 출력전력이 협대역 정합에서 최대 23dBm 정도인 중간전력급 증폭소자를 이용하여 광대역 이득을 갖는 직렬 분포형 증폭기 설계에 대하여 기술한다. 일반적으로 병렬 분포형 증폭기는 1단 증폭기처럼 이득이 낮고, 직렬 분포형 증폭기는 이득이 높은 반면에 출력전력의 크기가 10dBm 이내인 소신호 증폭기였던데 비하여, 본 논문에서는 광대역에서 출력 전력이 20dBm급인 직렬 분포형 증폭기에 대하여 기술한다. 실제로 제작한 증폭기는 $300MHz{\sim}2GHz$에서 $18.15{\pm}0.75dB$의 평탄한 이득과 $19{\sim}20dBm$의 출력전력 특성을 보이는 것으로 측정되어, 광대역에서 구동증폭기로 사용할 수 있음을 보여준다.

• 전기학회논문지
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• 제67권3호
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• pp.383-390
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• 2018

Piezoelectric micro-machined ultrasonic transducers for highly directional speaker need DC bias voltage. Most existing power amplifiers are not suitable for use in highly directional transducers because they are based on AC. In addition, since the piezoelectric micro-machined ultrasonic transducer has a large capacitive reactance, the power efficiency of the power amplifier is very low. Thus this paper proposes a new high efficiency power amplifier with DC bias voltage. In addition, by designing a matching circuit to compensate the capacitive reactance of the micro-machined ultrasonic transducer, the power efficiency of the power amplifier increases. The operating characteristics of the proposed power amplifier was verified by an experimental prototype. The proposed power amplifier is expected to be widely used in designing and implementing other related power amplifiers.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.1009-1012
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• 2000

In this paper, we have designed and fabricated power PHEMT’s with an unit gate width of 80$\mu\textrm{m}$ and 4 fingers, and MIMIC power amplifiers using the PHEMT’s as well. The PHEMT’s have a 0.2$\mu\textrm{m}$ gate length and source to drain spacing of 3$\mu\textrm{m}$. The characteristics of the fabricated PHEMT’s are 4.08dB of S$\sub$21/ gain at the 35GHz and 317mS/mm of gm, and 62GHz of f$\sub$T/ and 120GHz of f$\sub$max/. The designed and fabricated MIMIC’s power amplifiers with 6 PHEMT’s and MIN capacitors were fully passivated by 1000 Α of Si$_3$N$_4$ film for higher performance and surface protects. The chips were processed using the MINT processes, and size was 3.25 ${\times}$ 1.8$\textrm{mm}^2$. The fabricated MIMIC power amplifiers have RF characteristics such as 11.25dB of S$\sub$21/ gain, 11.37dB of input return-loss and 12.69dB of output return-loss at the 34.55GHz.

• 전기전자학회논문지
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• 제16권3호
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• pp.177-181
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• 2012

본 논문에서는 증폭기의 온도에 따른 균일한 출력특성을 구현하기 위한 개선된 보상특성을 갖는 증폭기용 온도보상회로를 제안한다. 제안된 온도보상회로는 직렬로 연결된 2개의 브랜치라인(Branchline) 결합기와 결합기 사이에 위치한 2개의 다이오드로 구성된다. 그리고, 회로의 주변온도에 따라서 저항값이 반비례하는 특서을 갖는 써미스터(Thermistor)와 써미스터를 포함하는 오피엠프(Operational amplifier, OP-Amp.)회로로 다이오드의 동작 특성을 조정함으로써 기존의 온도보상회로에 비하여 보다 효율적인 보상특성을 갖도록 설계하였다.

• Current Optics and Photonics
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• 제4권6호
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• pp.472-476
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• 2020

We have investigated the impact of optical filter bandwidth on the performance of all-optical automatic gain-controlled (AGC) erbium-doped fiber amplifiers (EDFAs). In principle, an optical bandpass filter (OBPF) should be placed within the feedback gain-clamping loop to set the lasing wavelength as well as the passband of the feedback amplified spontaneous emission (ASE) in all-optical AGC EDFA. From our measurement results, we found that the power level of feedback ASE with 0.1 nm passband of the optical filter was smaller than the ones with >0.2 nm passband cases. Therefore, the peak-to-peak power variation of the surviving channel with 0.1 nm passband was much larger than the ones with >0.2 nm passband. In addition, no significant difference in the power level of the feedback ASE was observed when the passband of the optical filter was ranging from 0.2 nm to 4.5 nm in our measurements. From these results, we have concluded that the passband of the optical filter should be slightly larger than 0.2 nm by taking into account the effect of feedback ASE power and the efficient use of the EDFA gain spectrum for the lasing ASE peak.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.675-678
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• 1998

In this paper, power amplifiers for PCS phone were designed with the GEC Marconi H40 HEMT libray. The 1st stage was carefully designed in order to obtain k〉1 using a parallel resistor, and its S21 gain of 18.3dB and input reflection coefficient of -4dB were obtained. And S21 gain of 18dB and input reflection coefficient of -7dB were obtained from the 2nd stage. Finally, total S21 gain of 38dB, input reflection coefficient of -16dB, power gain of 35.2dB, output power of 28.7dBm and PAE(power added efficiency) of 29% were obtained from the designed MMIC power amplifiers. The chip size is $1.729$\times$0.94\textrm{mm}^2.$

• 전자통신동향분석
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• 제36권3호
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• pp.53-64
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• 2021

As the 5G service market is expected to grow rapidly, the development of high-power, high-efficiency power amplifiers for the 5G communication infrastructure is indispensable. Gallium nitride (GaN) is attracting great interest as a key device in power devices and integrated circuits due to its wide bandgap, high carrier concentration, high electron mobility, and high-power saturation characteristics. In this study, we investigate the technology trends of Ka-band GaN radio frequency (RF) power devices and integrated circuits for operation in the millimeter-wave band of recent 5G mobile communication services. We review the characteristics of GaN RF high electron mobility transistor (HEMT) devices to implement power amplifiers operating at frequencies around 28 GHz and compare the technology of foreign companies with the device characteristics currently developed by the Electronics and Telecommunication Research Institute (ETRI). In addition, the characteristics of Ka-band GaN monolithic microwave integrated circuit (MMIC) power amplifiers manufactured using various GaN HEMT device technologies are reviewed by comparing characteristics such as frequency band, output power, and output power density of integrated circuits. In addition, by comparing the performance of the power amplifier developed by ETRI, the current status and future direction of domestic GaN power devices and integrated circuit technology will be discussed.

• 한국항행학회논문지
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• 제24권2호
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• pp.107-114
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• 2020

2.4 GHz ISM대역 전력증폭기를 설계하고 송신 시스템을 구현하였다. 고효율 증폭기는 E급이나 F급 증폭기로 구현 가능하다. 본 연구에서는 회로 구조가 간단한 E급으로 20 W 급 고효율 증폭기를 설계하여 ISM 대역 응용에 적용하도록 하였다. E급 회로 설계이론 및 회로 시뮬레이션을 통해 임피던스 정합회로를 설계하였으며 2.45 GHz에서 출력전력 44.2 dBm 및 전력부가효율 69%를 얻었다. 설계된 전력증폭기에 30 dBm의 입력전력을 인가하기 위하여 앞단에 전압제어발진기와 구동증폭기를 제작하여 입력전력 공급회로를 구현하였고, 제작한 전력증폭기는 43.2 dBm 출력 및 65%의 전력부가효율 특성을 나타내었다. 본 연구결과는 무선전력전송, 전파차단장치, 고출력 송신장치 등 다양한 무선통신시스템용 출력 전력증폭기 설계에 활용될 수 있다.

• ETRI Journal
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• 제25권3호
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• pp.195-202
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• 2003

This paper proposes a new LDMOSFET structure with a trenched sinker for high-power RF amplifiers. Using a low-temperature, deep-trench technology, we succeeded in drastically shrinking the sinker area to one-third the size of the conventional diffusion-type structure. The RF performance of the proposed device with a channel width of 5 mm showed a small signal gain of 16.5 dB and a maximum peak power of 32 dBm with a power-added efficiency of 25% at 2 GHz. Furthermore, the trench sinker, which was applied to the guard ring to suppress coupling between inductors, showed an excellent blocking performance below -40 dB at a frequency of up to 20 GHz. These results confirm that the proposed trenched sinker should be an effective technology both as a compact sinker for RF power devices and as a guard ring against coupling.