• Journal of Semiconductor Engineering
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• 제3권1호
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• pp.154-160
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• 2022

In this paper, we design a DC-DC boost converter with RF noise immunity to supply a stable positive output voltage for OLED displays. For RF noise immunity, an input voltage variation reduction circuit (IVVRC) is adopted to ensure display quality by reducing the undershoot and overshoot of output voltage. The boost converter for a positive voltage Vpos operates in the SPWM-PWM dual mode and has a dead-time controller using a dead-time detector, resulting in increased power efficiency. A chip was fabricated using a 0.18 um BCDMOS process. Measurement results show that power efficiency is 30% ~ 76% for load current range from 1 mA to 100 mA. The boost converter with the IVVRC has an overshoot of 6 mV and undershoot of 4 mV compared to a boost converter without that circuit with 18 mV and 20 mV, respectively.

• Journal of information and communication convergence engineering
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• 제18권4호
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• pp.254-259
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• 2020

Phased-array antennas comprise a demanding antenna design methodology for commercial wireless communication systems or military radar systems. In addition to these two important applications, the phased-array antennas can be used in beamforming for wireless charging. In this study, a four-way analog beamforming front-end module (FEM) for a hybrid beamforming system is developed for 2.4 GHz operation. In a hybrid beamforming scheme, an analog beamforming FEM in which the phase and amplitude of RF signal can be adjusted between the RF chain and phased-array antenna is required. With the beamforming and beam steering capability of the phased-array antennas, wireless RF power can be transmitted with high directivity to a designated receiver for wireless charging. The four-way analog beamforming FEM has a 32 dB gain dynamic range and a phase shifting range greater than 360°. The maximum output RF power of the four-way analog beamforming FEM is 40 dBm (=10 W) when combined the four individual RF paths are combined.

• 한국통신학회논문지
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• 제27권3C호
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• pp.248-255
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• 2002

IEEE 802.11a 무선 랜 규격을 만족하는 RF 송수신기를 모듈의 형태로 제작하고 성능을 평가하였다. 주파수 변환 방식은 520MHz의 중간 주파수를 갖는 헤테로다인 구조를 채택하였다. 측정 결과 수신기는 잡음지수 5dB, 최대 이득 70dB, 그리고 61dB의 넓은 입력 동작 범위를 얻었다. 또한 중간 주파수 대역의 채널 선정 필터는 SAW 필터를 채용하여 채널간의 간섭 잡음을 최소화하였다. 송신기는 규격에 정의된 정격 출력을 만족하는 동시에 34dBm의 출력 P1dB를 가져 낮은 대역, 중간 대역에 대해 각각 18dB, 11dB의 출력 여유분을 보유함으로써 직교 주파수 분할 다중(OFDM) 변조방식의 큰 평균대비 최고 출력 비율에 대응하였다.

• ETRI Journal
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• 제27권5호
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• pp.569-578
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• 2005

The purpose of this paper is to describe the implementation of monolithically matching circuits, interface circuits, and RF core circuits to the same substrate. We designed and fabricated on-chip 1 to 6 GHz up-conversion and 1 to 8 GHz down-conversion mixers using a 0.8 mm SiGe hetero-junction bipolar transistor (HBT) process technology. To fabricate a SiGe HBT, we used a reduced pressure chemical vapor deposition (RPCVD) system to grow a base epitaxial layer, and we adopted local oxidation of silicon (LOCOS) isolation to separate the device terminals. An up-conversion mixer was implemented on-chip using an intermediate frequency (IF) matching circuit, local oscillator (LO)/radio frequency (RF) wideband matching circuits, LO/IF input balun circuits, and an RF output balun circuit. The measured results of the fabricated up-conversion mixer show a positive power conversion gain from 1 to 6 GHz and a bandwidth of about 4.5 GHz. Also, the down-conversion mixer was implemented on-chip using LO/RF wideband matching circuits, LO/RF input balun circuits, and an IF output balun circuit. The measured results of the fabricated down-conversion mixer show a positive power conversion gain from 1 to 8 GHz and a bandwidth of about 4.5 GHz.

• 한국통신학회논문지
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• 제32권1A호
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• pp.91-100
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• 2007

본 논문에서는 저출력 모바일 RFID 리더의 인식 거리를 확대시키기 위하여 20Watts 급의 전력 공급용 RF Shower 시스템을 개발하였으며, 실험을 통하여 Shower 시스템의 출력을 조절하면 리더-태그 간 인식거리가 3배 이상 늘어나는 것을 확인하였다. 향후 RF Shower 시스템을 이용하여 Shower Zone 설계를 적절히 함으로써 저출력 리더(20dBm이하)를 사용하면서 기존 RFID 시스템의 인식거리를 획기적으로 확장할 수 있을 것으로 기대된다.

• 한국전자파학회논문지
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• 제27권1호
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• pp.76-79
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• 2016

본 논문에서는 ETRI에서 개발된 50 W GaN-on-SiC HEMT 소자를 이용하여 X-band에서 동작하는 50 W 펄스 전력증폭기의 개발 결과를 정리하였다. 제작된 50 W GaN HEMT 소자는 $0.25{\mu}m$의 게이트 길이를 갖고, 총 게이트 폭은 12 mm인 소자이다. 펄스 전력증폭기는 9.2~9.5 GHz 주파수 대역에서 50 W의 출력전력과 6 dB의 전력이득 특성을 나타내었다. 전력소자의 전력밀도는 4.16 W/mm이다. 제작된 GaN-on-SiC HEMT 소자와 전력증폭기는 X-대역 레이더 시스템 등 다양한 응용분야에 적용이 가능할 것으로 판단된다.

• Journal of electromagnetic engineering and science
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• 제14권4호
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• pp.342-345
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• 2014

An active frequency doubler monolithic microwave integrated circuit (MMIC) for E-band transceiver applications is presented in this letter. This MMIC has been fabricated in a commercial $0.1-{\mu}m$ GaAs pseudomorphic high electron mobility transistor (pHEMT) process on a 2-mil thick substrate wafer. The fabricated MMIC chip has been measured to have a high output power performance of over 13 dBm with a high fundamental leakage suppression of more than 38 dBc in the frequency range of 71 to 86 GHz under an input signal condition of 10 dBm. A microstrip coupled line is used at the output circuit of the doubler section to implement impedance matching and simultaneously enhance the fundamental leakage suppression. The fabricated chip is has a size of $2.5mm{\times}1.2mm$.

• Journal of Semiconductor Engineering
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• 제1권1호
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• pp.13-30
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• 2020

Radio frequency (RF) energy harvesting technology have become a reliable and promising alternative to extend the lifetime of power-constrained wireless networks by eliminating the need for batteries. This emerging technology enables the low-power wireless devices to be self-sustaining and eco-friendly by scavenging RF energy from ambient environment or dedicated energy sources. These attributes make RF energy harvesting technology feasible and attractive to an extended range of applications. However, despite being the most reliable energy harvesting technology, there are several challenges (especially power conversion efficiency, output DC voltage and sensitivity) poised for the implementation of RF energy harvesting systems. In this article, a detailed literature on RF energy harvesting technology has been surveyed to provide guidance for RF energy harvesters design. Since signal strength of the received RF power is limited and weak, high efficiency state-of-the-art RF energy harvesters are required to design for providing sufficient DC supply voltage to wireless networks. Therefore, various designs and their trade-offs with comprehensive analysis for RF energy harvesters have been discussed. This paper can serve as a good reference for the researchers to catch new research topics in the field of RF energy harvesting.

• 전기전자학회논문지
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• 제24권3호
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• pp.853-858
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• 2020

본 논문은 통신기기에서 유입 되는 RF 노이즈에 대해 내성을 가진 OLED용 2-채널 DC-DC 변환기를 제안한다. RF 신호 내성을 위해, 입력전압 변동만큼 감쇠시키는 입력전압 변동감쇠 회로가 내장된다. 양의 전압 V_POS를 출력하는 부스트 변환기는 SPWM-PWM 듀얼모드로 동작하고, 데드 타임을 제어함으로써 전력 효율을 제고한다. V_NEG를 출력하는 인버팅 차지펌프는 2-상 출력 구조로 VCO를 이용한 PFM으로 동작해 작은 리플을 갖도록 설계된다. 0.18 ㎛ BCDMOS 공정으로 시뮬레이션 한 결과, 부스트 변환기 출력전압의 오버슈트와 언더슈트는 10 mV에서 각각 2 mV, 5 mV로 감소하였다. 또한, 2-채널 DC-DC 변환기의 전력효율은 39%~93%을 가졌고, 데드 타임 제어기를 적용한 부스트 변환기의 효율은 종전보다 최대 3% 증가하였다.

• 전자공학회논문지D
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• 제34D권10호
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• pp.24-31
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• 1997

A new design method of stable RF power amplifier using 3dB coupled line is proposed in this thiesis. The proposed method of broadband matching consist of resistive matching circuits at low frequency and lossless matching circuits at microwave band. This design method increase the stability of an amplifier and is suitable for interstage matching. When high power amplifier is designed using this method for PCS base transceiver station, the measured resutls show thst the gain of 18.5dB, and 9W (39.5dBm) output power. We use motorola's MRF6401 for medium power and MRF 6402 for large power and cascaded them.