• Journal of Communications and Networks
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• 제10권1호
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• pp.55-62
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• 2008

Bandpass sampling (BPS) techniques for the direct down-conversion of RF bandpass signals have become an essential technique for software defined radio (SDR), due to their advantage of minimizing the radio frequency (RF) front-end hardware dependency. This paper proposes an algorithm for finding the minimum BPS frequency for simultaneously down-converting multiple RF signals through full permutation over all the valid sampling ranges found for the multiple RF signals. We also present a scheme for reducing the computational complexity resulting from the large scale of the purmutation calculation involved in searching for the minimum BPS frequency. In addition, we investigate the BPS frequency allowing for the guard-band between adajacent down-converted signals, which help lessen the severe requirements in practical implementations. The performance of the proposed method is compared with those of other pre-reported methods to prove its effectiveness.

• 한국전자파학회논문지
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• 제19권11호
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• pp.1287-1293
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• 2008

4중 대역의 안테나 스위치 모듈을 개발하였다. 단말기의 front-end 단에서 LTCC 형태의 저역 통과 필터, 다이오드 및 수동 부품들로 구현되는 스위치 부분을 대신하여 수동 집적 회로와 트랜지스터 스위치로 집적화한 것이다. 필터의 수동 소자 및 정합 회로를 통합 구성하여 크기 면에서도 소형화가 가능하고, 가격 경쟁력에서도 우위를 점할 수 있다. 제안하는 안테나 스위치 모듈의 크기는 $5{\times}5\;mm$이고, 두께는 0.8 mm로 제작되었다. 각 대역의 삽입 손실은 평균적으로 1.0 dB이며, 반사 손실은 GSM/EGSM 대역에서 15.1 dB, DCS/PCS 대역에서 19 dB이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.107-108
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• 2008

This article describes optimization for PGS(Patterned Ground Shield) of rectangular spiral inductor using Taguchi's Design of Experiment. PGS is decrease method of parasite component by silicon substrate among dielectric loss reduction method. Using taguchi's design of experiment, each parameter is fixed upon that PGS high poison(A), slot spacing(B), strip width(C) and overlap turn number(D) of PGS design parameter. Then we verified that percentage contribution and design sensitivity analysis of each parameter and level by signal to noise ratio of larger-the-better type. We consider percentage contribution and design sensitivity of each parameter and level, and then verify that model of optimization for PGS is lower inductance decreasing ratio and higher Q-factor increasing ratio by EM simulation.

• 전자공학회논문지
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• 제50권10호
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• pp.98-104
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• 2013

본 논문에서는 무선 통신 및 근거리 위치 인식이 가능한 WBAN(wireless body area network) 용 UWB(Ultra-wide band) 수신기 회로를 제안한다. UWB 수신기는 에너지 검출 방식의 OOK(on-off keying) 변조가 가능하도록 설계가 되었다. 고속의 sampling 을 하기 위해서 4bit ADC 는 DLL(delay locked loop) 을 이용하여 sub-sampling 기법을 사용하도록 설계되었다. 제안된 UWB 수신기는 CMOS $0.18{\mu}m$ 공정을 이용하여 설계되었으며, 전원 전압 1.8V에서 61mA의 전류를 소모하면서 -85.7dBm의 수신 감도, 42.1dB의 RF front-end 게인, 3.88 dB의 noise figure, 최대 4m 까지의 거리 감지 성능을 가지고 있다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.391-394
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• 2006

The paper deals with the experimental GNSS receiver built at the Czech Technical University for experiments with the real GNSS signal. The receiver is based on software defined radio architecture. Receiver consists of the RF front end and a digital processor based on programmable logic. Receiver RF front end supports GPS L1, L2, L5, WAAS/EGNOS, GALILEO L1, E5A, E5B signals as well as GLONASS L1 and L2 signals. The digital processor is based on Field Programmable Gate Array (FPGA) which supports embedded processor. The receiver is used for various experiments with the GNSS signals like GPS L1/EGNOS receiver, GLONASS receiver and investigation of the EGNOS signal availability for a land mobile user. On the base of experimental GNSS receiver the GPS L1, L2, EGNOS receiver for railway application was designed. The experimental receiver is also used in GNSS monitoring station, which is independent monitoring facility providing also raw monitoring data of the GPS, EGNOS and Galileo systems via internet.

• Journal of electromagnetic engineering and science
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• 제12권4호
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• pp.234-239
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• 2012

This paper presents a compact K-band Doppler radar sensor for human vital signal detection that uses a radar configuration with only single coupler. The proposed radar front-end configuration can reduce the chip size and the additional RF power loss. The radar front-end IC is composed of a Lange coupler, VCO, and single balanced mixer. The oscillation frequency of the VCO is from 27.3 to 27.8 GHz. The phase noise of the VCO is -91.2 dBc/Hz at a 1 MHz offset frequency, and the output power is -4.8 dBm. The conversion gain of the mixer is about 11 dB. The chip size is $0.89{\times}1.47mm^2$. The compact Ka-band Doppler radar system was developed in order to demonstrate remote human vital signal detection. The radar system consists of a Ka-band Doppler radar module with a $2{\times}2$ patch array antenna, baseband signal conditioning block, DAQ system, and signal processing program. The front-end module size is $2.5{\times}2.5cm^2$. The proposed radar sensor can properly capture a human heartbeat and respiration rate at the distance of 50 cm.

• 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.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1121-1124
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• 1998

A CMOS RF bandpass amplifier which performs both functions of low-noise amplifier and bandpass filter is designed for the application of 1.9 ㎓ RF front-end in wireless receivers. The positive-feedback Q-enhancement technique is used to overcome the low gain and low Q factor of the bandpass amplifier. The designed bandpass amplifier is simulated with HSPICE and fabricated using HYUNDAI $0.8\mu\textrm{m}$ CMOS 2-poly 2-metal full custom process. Under 3 V supply voltage, results of simulation show that the CMOS bandpass amplifier provides the power gain 23dB, noise figure 3.8 dB, and power dissipation 55mW.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.231-233
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• 2005

For the low-power design of the mobile multimedia system architecture, this paper modeling the mobile multimedia system and analysis the power consumption profile about the whole communication environment. The mobile system model consist of air interface, RIP front-end, base-band processing module and human interface. For the result of power consumption profile analysis, the power consumption of multimedia processing is above 60% compare to the whole power consumption in mobile multimedia system. To minimize the power consumption in processing module which consumes the large power, this paper proposed the Microscopic DVS technique which applies the optimum voltage for the each multimedia frame. For the simulation result, proposed power minimization technique reduce the power consumption about 30%.

• Journal of information and communication convergence engineering
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• 제17권3호
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• pp.221-226
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• 2019

In this work, a transmitter/receiver front-end module (T/R FEM) with an automatic Tx/Rx switching scheme for a 2.4 GHz microwave power transfer is developed for a retro-reflective beamforming scheme. Recently, research on wireless power transfer techniques has moved to wireless charging systems for mobile devices. Retro-reflective beamforming is a good candidate for tracking the spatial position of a mobile device to be charged. In Tx mode, the T/R FEM generates a minimum of 1 W. It also comprises an amplitude and phase monitoring port for transmitting RF power. In Rx mode, it passes an Rx pilot signal from a mobile device to a digital baseband subsystem to recognize the position of the mobile device. The insertion loss of the Rx signal path is 4.5 dB. The Tx and Rx modes are automatically switched by detecting the Tx input power. This T/R FEM is a design example of T/R FEMs for wireless charging systems based on a retro-reflective beamforming scheme.