• International Journal of Internet, Broadcasting and Communication
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• 제15권3호
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• pp.122-128
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• 2023

This paper proposes two kinds of single-balanced direct conversion quadrature receivers using selfoscillating LMVs in which the voltage-controlled oscillator (VCO) itself operates as a mixer while generating an oscillation. The two LMVs are complementary coupled and series coupled to generate the quadrature oscillating signals, respectively. Using a 65 nm CMOS technology, the proposed quadrature receivers are designed and simulated. Oscillating at around 2.4 GHz frequency, the complementary coupled quadrature receiver achieves the phase noise of -28 dBc/Hz at 1KHz offset and -109 dBc/Hz at 1 MHz offset frequency. The other series coupled receiver achieves the phase noise of -31 dBc/Hz at 1KHz offset and -109 dBc/Hz at 1 MHz offset frequency. The simulated voltage conversion gain of the two single-balanced receivers is 37 dB and 45 dB, respectively. The double-sideband noise figure of the two receivers is 5.3 dB at 1 MHz offset. The quadrature receivers consume about 440 μW dc power from a 1.0-V supply.

• 한국광학회지
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• 제17권2호
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• pp.181-185
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• 2006

리튬나이오베이트 기판의 분극 반전 기술을 이용하여 300Hz 대역 광변조기를 제작하였고 60 GHz 광캐리어 발생기로 응용하였다. 주기적인 분극반전은 도파광과 RF사이의 QVM(Quasi-Velocity-Matching)을 유발하여 대역변조를 가능하게 하였다. 제작된 광변조기는 30.3 GHz에서 최대 변조효율을 보였으며, 3 dB 변조 대역폭은 약 5.1 GHz로 측정되었다. DSB-SC(Double Sideband Suppressed Carrier) 측정 실험을 통해 입사된 광 주파수로부터 30 GHz 간격으로 USB(Upper Sideband)와 LSB(Lower Sideband)를 발생시켰으며 입사광의 스펙트럼은 발생된 USB 혹은 LSB에 비해 28 dB정도 억제됨으로써, 30GHz 대역 광변조기가 60 GHz 광캐리어 발생기로 응용될 수 있음을 보였다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1995년도 한국우주과학회보 제4권1호
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• pp.19-19
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• 1995

No Abstract. See Full-text

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.195-196
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• 2008

A ring resonator based band-pass filter enabling enhanced sideband suppression was proposed and demonstrated. It is composed of a single-ring based-pass section combined with a band-rejection section based on two different coupled rings. As for the achieved device performance, bandwidth was reduced from 98 MHz to 48 MHz by about 51% with no remarkable excessive insertion loss as expected. And the quality factor of the device was increased by about 105%.

• 한국광학회지
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• 제14권1호
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• pp.51-57
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• 2003

물체의 홀로그램은 물체의 깊이위치에 대한 정보뿐 아니라 물체의 깊이분포에 대한 정보도 가지고 있다. 그러나 두 가지 정보는 프린지 패턴(fringe pattern)의 형태로 서로 썩여있어 홀로그램으로부터 물체의 깊이위치에 대한 정보를 분리해내기 어렵다. 본 논문에서는 물체의 깊이 및 위치분포에 대한 정보를 갖는 단일 결띠 홀로그램(single-sideband hologram)으로부터 물체의 깊이위치에 대한 정보만을 가우시안 저-대역 필터를 이용해 추출해내고 그를 수치적 방법으로 해석해 물체의 깊이위치를 얻어내는 알고리즘을 제안한다. 또한 추출된 깊이위치를 이용하여 물체의 깊이위치에서 홀로그램을 복원해낸다.

• Journal of Astronomy and Space Sciences
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• 제23권1호
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• pp.19-28
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• 2006

The noise temperature of existing millimeter-wave receivers is already within two or three times quantum noise limit. One of practical ways to increase the observation speed of single dish radio telescope without longer integration time is use of multi-beam focal plane array receiver as demonstrated in several large single dish radio telescopes. In this context the TRAO (Taeduk Radio Astronomy Observatory), which operates a 143n Cassegrain radio telescope, is planning to develop a 4 x 4 beams focal plane array SIS receiver system for 86-115 GHz band. Even though millimeter-wave HEMT LNA-based receivers approach the noise temperature comparable to the SIS receiver at W-band, it is believed that the receiver based on SIS mixer seems to offer a bit more advantages. The critical part of the multi-beam array receiver will be sideband separating SIS mixers. Employing such a type of SIS mixer makes it possible to simplify the quasi-optics of receiver. Otherwise, an SSB filter should be used in front of the mixer or some sophisticated post-processing of observation data is needed. In this paper we will present a preliminary design concept and components needed for the development of a new 3 mm band multi-beam focal plane array receiver.

• 비파괴검사학회지
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• 제34권6호
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• pp.419-427
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• 2014

Nonlinear features of ultrasonic waves are more sensitive to the presence of a fatigue crack than their linear counterparts are. For this reason, the use of nonlinear ultrasonic techniques to detect a fatigue crack at its early stage has been widely investigated. Of the different proposed techniques, laser nonlinear wave modulation spectroscopy (LNWMS) is unique because a pulse laser is used to exert a single broadband input and a noncontact measurement can be performed. Broadband excitation causes a nonlinear source to exhibit modulation at multiple spectral peaks owing to interactions among various input frequency components. A feature called maximum sideband peak count difference (MSPCD), which is extracted from the spectral plot, measures the degree of crack-induced material nonlinearity. First, the ratios of spectral peaks whose amplitudes are above a moving threshold to the total number of peaks are computed for spectral signals obtained from the pristine and the current state of a target structure. Then, the difference of these ratios are computed as a function of the moving threshold. Finally, the MSPCD is defined as the maximum difference between these ratios. The basic premise is that the MSPCD will increase as the nonlinearity of the material increases. This technique has been used successfully for localizing fatigue cracks in metallic plates.

• Journal of the Optical Society of Korea
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• 제17권1호
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• pp.63-67
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• 2013

We perform an optical vestigial sideband (VSB) filtering using a pair of Fabry-Perot (FP) filters. The transmittance curve of each FP filter is made to have sharp skirts using an offset between input and output coupling fibers. Moreover, the accurate periodicity of FP filters in the optical frequency domain enables the simultaneous VSB filtering of a large number of optical channels. With this VSB filtering technique, we transmit 12.5-GHz spaced $64{\times}12.4-Gb/s$ wavelength-division-multiplexing channels over a single-mode fiber up to 150 km without any dispersion compensations. When the channel spacing is reduced to 10 GHz, we achieve the spectral efficiency of 1 bit/s/Hz in conventional optical intensity modulation systems up to 125 km.

• 천문학회보
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• 제33권1호
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• pp.50.2-50.2
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• 2008

• 대한전자공학회논문지TC
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• 제43권9호
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• pp.158-164
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• 2006

WLAN 및 이동통신은 계속해서 많은 서로 다른 표준으로 진화함에 따라 이동통신 사업자는 기술적 경제적 많은 어려움에 직면하고 있다. 따라서 끊임없는 시스템 업그레이드가 필요하게 된다. 이러한 문제를 해결하기 위한 새로운 접근 방법을 모색하여 그 타당성을 연구하였다. 즉, electro-absorption modulator(EAM) 과 optical single sideband (OSSB)에 기반한 radio over fiber (RoF) 기술을 사용해 저가, 단순, 주파수변화 및 프로토콜 변화가 없는 트랜스패런트한 무선 액세스 망을 구축하여 그 해결책을 제시하였다. 본 논문에서는 프로토타입 CATV 용 60GHz 대 무선 RoF 분배시스템을 구축하여 broadband convergence network (BcN)의 무선 액세스망에 사용가능성을 타진하였다.