• Journal of information and communication convergence engineering
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• 제6권4호
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• pp.439-443
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• 2008

It is shown that even if the modulating frequency of the light is too high for direct detection the signal can be extracted by frequency conversion at the same time as the detection by means of the nonlinearity of the APD. When this frequency conversion detection is applied to an optical receiver, the detection bandwidth can be increased while the configuration of the optical detection circuit and the signal processing in the subsequent stages are simplified. A fundamental analysis is carried out with an APD which is confirmed experimentally.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.305-308
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• 2009

This paper presents the design and analysis of RF Front End for Wireless Heartbeat measurement System. In this work LNA, an inductor connected at the gate of the cascode transistor and capacitive cross-coupling are strategically combined to reduce the noise and the nonlinearity influences of the cascode transistors in a differential LNA. The Mixer is implemented by using the Gilbert-type configuration, cross pmos injection technique and the resonating technique for the tail capacitance. The resulting LNA achieves 1.26 dB NF, better than 1.88dB NF Typical Also Mixer resulting achieves 9.8dB at 100KHz.

• 한국정보통신학회논문지
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• 제13권11호
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• pp.2267-2272
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• 2009

본 논문에서는 다층형 결합 선로를 이용한 6-단자 위상 상관기와 동일한 구조를 갖는 반송파 복원기 그리고 위상 변위기를 갖는 일원화된 6-단자 직접변환 수신 전처리부를 설계 제작한다. 전력 분배기와 하이브리드 결합기로 구성되는 6-단자 소자는 다층형 결합 선로 구조로 이루어지며, 수신부 위상 상관기와 반송파 복원기 그리고 위상 변위기의 기본 구조 요소로 작용한다. 다층형 결합 선로 구조로 구성되는 일원화된 수신 전처리부는 구성이 간단하고 집적화가 용이하다. 설계 제작된 다층형 결합 구조 6-단자 수신 전처리부는 일정한 반송파 신호를 재생하고, PSK 전송 신호를 복원한다.

• 한국위성정보통신학회논문지
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• 제1권1호
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• pp.59-64
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• 2006

본 논문에서는 직접 변환 방식인 six-port의 RF 출력 신호를 검파하고 요구 대역폭에서 입력 주파수 신호에 대한 진폭 및 위상 신호를 선형적으로 출력하는 광역 power detector를 설계 제작한다. Six-port 출력단에 접속되는 power detector는 높은 정합도를 갖고 반사파로 인한 Six-port 간 위상 불일치를 방지하고, 넓은 대역폭에서 낮은 VSWR을 유지하여야 하는 광역 특성을 갖는 power detector 설계가 필요하다. 광역 정합을 위하여 사용 주파수 대역에 따라 강제 정합과 다단 LC 정합 회로, 그리고 isolator를 사용한 낮은 VSWR 특성을 갖는 설계 방법을 비교 분석한다. 설계 제작된 power detector의 주파수 대역에 대한 동적 동작 영역(dynamic range) 성능을 측정하여 Six-port의 수신 전송 신호 검파기로 활용될 수 있는 타당성을 평가한다.

• Journal of electromagnetic engineering and science
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• 제8권3호
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• pp.114-118
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• 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.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.205-209
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• 2000

현재의 무선통신기기는 다양한 멀티미디어의 제공과 함께 저전력, 소형·경량화, 단말기 가격의 저렴화가 개발의 목표가 되고 있다. 그러나, 기존의 무선통신시스템인 헤테로다윈 방식으로는 사용부품의 다양성 때문에 소형·경량화 및 부품의 On-Chip 작업에 어려움이 있어 미래형무선통신의 시스템으로는 적합하지 못하다. 이에 현재 연구개발이 진행되고 있는 방식 직접변환(Direct-Conversion)방식이다. 직접변환방식은 무선주파수 대역을 바로 기저대역을 하향변환 하므로써, 부가적인 부품의 사용과 소비전력의 감소에 상당한 이점이 있다. 이에 직접변환방식에 대한 이론적 설명과 함께 현재 무선통신 시스템으로 사용하기 위해 해결해야될 과제인 DC-Offset의 설명과 그 제거방법중의 하나인 AC-Coupling 기법의 시스템 적용으로 인한 시스템의 성능향상을 예측하고자한다

• JSTS:Journal of Semiconductor Technology and Science
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• 제4권3호
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• pp.174-181
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• 2004

In this paper, we review the four receiver architectures and four methods for multi-standard receiver design. Propose reconfigurable RF block can be used for both low-IF and direct conversion architecture. Also, using reconfigurable mixer method, it can be operated at $2{\sim}6$ GHz range for multi-standard receiver. It consists of wideband mixer, filter, and automatic gain control amplifier and to get wide-band operation, $2{\sim}6$ GHz, wide-band mixer use flexible input matching method. Besides, to design multi-standard receiver, LNA bank that support each standard is necessary and it has good performance to compensate the performance of wide-band mixer. Finally, we design and simulate proposed reconfigurable RF block and to prove that it has acceptable performances for various wireless standards, the LNA bank that supports both IEEE 802.11a/b/g and WCDMA is also designed and simulated with it.

• 방송과미디어
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• 제11권1호
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• pp.78-85
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• 2006

Cognitive radio is a paradigm for wireless communication in which either network of wireless node itself changes particular transmission or reception parameters to execute its tasks efficiently without interfering with the licensed users. This paper represents a performance of the cognitive radio technology on dual polarized MIMO system using six-port receiver. Six-port technology is well known direct conversion receiver. In this paper, a six-port phase discriminator based polarization signal separation is shown. That is, the SER(Symbol Error Rate) performance is improved using polarization separator and simple receiver architecture is proposed applying six-port receiver. The six-port technology has priority to adapt changeable frequency system and variable environments for cognitive radio. In general, dual polarized MIMO system has good capacity and quality using polarization separator [1].

• Journal of electromagnetic engineering and science
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• 제4권4호
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• pp.143-149
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• 2004

This paper describes characteristics of the single-balanced low IF resistive FET mixer for the digital beam forming(DBF) receiver. This DBF receiver based on the direct conversion method is designed with Low IF I and Q channel. A radio frequency(RF), a local oscillator(LO) and an intermediate frequency(IF) considered in this research are 1950 MHz, 1940 MHz and 10 MHz, respectively. Super low noise HJ FET of NE3210S01 is considered in design. The measured results of the proposed mixer are observed IF output power of -22.8 dBm without spurious signal at 10 MHz, conversion loss of -12.8 dB, isolation characteristics of -20 dB below, 1 dB gain compression point(PldB) of -3.9 dBm, input third order intercept point(IIP3) of 20 dBm, output third order intercept point(OIP3) of 4 dBm and dynamic range of 30 dBm. The proposed mixer has 1.0 dB higher IIP3 than previously published single-balanced resistive and GaAs FET mixers, and has 3.0 dB higher IIP3 and 4.3 dB higher PldB than CMOS mixers. This mixer was fabricated on 0.7874 mm thick microstrip $substrate(\varepsilon_r=2.5)$ and the total size is $123.1\;mm\times107.6\;mm$.

• Journal of Electrical Engineering and Technology
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• 제7권1호
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• pp.81-85
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• 2012

This paper presents a wideband and low-noise direct conversion front-end receiver supporting VHF and UHFbands simultaneously. The receiver iscomposed of a low-noise amplifier (LNA), a down conversion quadrature mixer, and a frequency divider by 2. The cascode configuration with the resistor feedback is exploited in the LNA to achieve a wide operating bandwidth. Four gainstep modesare employed using a switched resistor bank and a capacitor bank in the signal path to cope with wide dynamic input power range. The verticalbipolar junction transistors are used as the switching elements in the mixer to reduce 1/f noise corner frequency. The proposed front-end receiver fabricated in 0.18 ${\mu}m$ CMOS technology shows very low minimum noise figureof 1.8 dB and third order input intercept pointof -12dBm inthe high-gain mode of 26.5 dBmeasured at 500 MHz.The proposed receiverconsumeslow current of 20 mA from a 1.8 V power supply.