• 한국통신학회논문지
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• 제30권7C호
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• pp.687-695
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• 2005

차세대 통신기술인 Software-Defined Radio (SDR)시스템은 단일 하드웨어 플랫폼에 소프트웨어 변경만으로 다양한 통신표준을 수용할 수 있는 시스템이다. 시스템의 융통성(flexibility)과 적응성(adaptability)을 위하여 RF와 관련된 하드웨어의 최소화가 필요하며, 이를 위해 ADC를 사용으로 기저대역(baseband) 또는 낮은 IF단으로 직접하향 변환(downconversion)을 할 수 있는 bandpass sampling 기법이 필수적이다. 이 논문에서는 complex bandpass sampling 방식을 이용하여 두 가지의 통신 표준이 한 시스템에서 동시에 직접 하향 변환하는 새로운 방법을 제안하였다. 이에 따른 sampling 가능 영역, 보호대역(guard-band)을 고려한 sampling 가능 최소 주파수 그리고 이동된 신호의 위치를 구하는 수식들을 유도한 뒤 그래프를 통해 비교 분석하였다. 또한 제안한 sampling방식이 모의실험을 통해 기존에 제안되었던 real bandpass sampling방식보다 SDR시스템에 더욱 적합하다는 것을 입증하였다.

• 한국통신학회논문지
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• 제30권9C호
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• pp.913-921
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• 2005

일반적인 bandpass sampling 방법인 real bandpass sampling 기법은 하향변환(downconversion)을 시행할 때 음의 주파수 대역의 RF 신호와의 에일리어싱(aliasing) 현상을 피해야 하므로 신중한 sampling 주파수 선택이 요구된다. 더욱이 다중신호(multiple signals)가 하향변환 될 경우에 이 sampling 방법은 더욱 많은 제약이 따르게 된다. 그러나 Hilbert 변환을 사용하는 complex bandpass sampling 방법은 음의 주파수 영역의 신호를 제거함으로써, real bandpass sampling 기법보다 유연하고 넓은 sampling 주파수 범위를 제공하며, 또한 더욱 낮은 sampling 주파수를 얻을 수 있는 장점이 있다. 본 논문에서는 이러한 complex bandpass sampling의 특징을 사용하여, 다중 신호를 하나의 통신 기기에서 동시에 하향 변환하는 수신기의 구조를 제시한다. 그리고 하나 또는 2개 신호의 하향변환에 관한 내용으로 제한하지 않고 N개의 신호로 확장하여 유효 sampling 주파수 영역 및 보호대역(guard-band)이 고려된 sampling 가능 최소 주파수에 관한 수식들을 일반화한다. 또한 모의실험을 통해 유도된 수식들을 증명한다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.234-238
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• 2003

The LTCC bandpass filter using multilayer resonators is made of combline type and interdigital type parallel coupled-lines. The equivalent circuits of parallel coupled-lines are analysed. They are applied to make an equivalent circuit of LTCC bandpass filter using multilayer resonators. The 3-pole bandpass filter of the center frequency of 2.45GHz with 250Hz bandwidth is designed and fabricated. The simulated result of the bandpass filter are presented.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.313-316
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• 2003

The LTCC bandpass filter using multilayer resonators is made of combline type and interdigital type parallel coupled-lines. The equivalent circuits of parallel coupled-lines are analysed. They are applied to make an equivalent circuit of LTCC bandpass filter using multilayer resonators. The 3-pole bandpass filter of the center frequency of 2.45GHz with 200Hz bandwidth is designed and fabricated. The simulated result of the bandpass filter are presented.

• Journal of electromagnetic engineering and science
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• 제3권2호
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• pp.126-132
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• 2003

In this paper, a coupled-line type waveguide bandpass filter is newly proposed. The proposed bandpass filter configuration consists of magnetically coupled waveguide cavities. In order to show the background of the proposed waveguide bandpass filter, the general coupled line TEM bandpass filter theory, which means the coupled line filter with arbitrary coupled line length and impedance level, will be briefly introduced. Calculations for the even- and odd-mode wave impedance of a coupled line waveguide structure are achieved based on the normalized impedance concept for a broad-side coupled waveguides by using vector finite element method(VFEM) calculation. Measured result of an implemented coupled-line type waveguide filter is presented.

• 융합신호처리학회논문지
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• 제14권2호
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• pp.70-76
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• 2013

In this paper, we propose the bandpass form of discrete prolate spheroidal sequences(DPSS) which have the maximal energy concentration in a given passband and as such are very appropriate to obtain a projection of signals. The basic properties of the bandpass DPSS are also presented. Assuming a signal satisfies the finite time support and the essential band-limitedness conditions with a known center frequency, signal representation and interpolation techniques for band-limited signals using the bandpass DPSS are introduced where the reconstructed signal has minimal out-of-band energy. Simulation results are given to present the usefulness of the bandpass DPSS for efficient representation of band-limited signal.

• 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.

• 전자공학회논문지D
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• 제34D권9호
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• pp.15-20
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• 1997

Waveguide bandpass filters using E-plane or H-plane discontinuities have been used in many satellite communication systems. Since the transmitter and receiver of such systems tend to be getting smaller, components such as bandpass filters must also be reduced in size. In this paper, in order to reduce the waveguide, itself, of which bandpass filters consist, double plane step waveguide discontinuities are considered. They are analyzed using the mode matching method and the genralized scattering parameter of the cascaded structure is calculated. The characteristics of the bandpass filter which is designed using the reduced size waveguide is optimized by OSA90$^{TM}$. The bandpass filter has a good characteristics and smaller size than those made of the E-plane or H-plane step discontinuities.s.

• 한국항해항만학회지
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• 제36권9호
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• pp.737-740
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• 2012

A miniaturized CMOS bandpass filter for a single RF transceiver system is presented, using diagonally end-shorted coupled lines and lumped capacitors. In contrast to conventional miniaturized coupled line filters, it is proven that the effective permittivity variation of the coupled transmission line has no effect on shifting the center frequency when the bandpass filter is highly miniaturized. A bandpass filter at a center frequency of 2 GHz was fabricated by $0.18{\mu}m$ CMOS technology. The insertion loss with the die area of $1500{\mu}m{\times}1000{\mu}m$ is -5.14 dB. Simulated results are well agreed with the easurements. It also verify the center frequency stability in the compact size bandpass filter.

• Journal of electromagnetic engineering and science
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• 제1권1호
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• pp.83-87
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• 2001

Many communication systems require bandpass filters with sharp skirt frequency characteristics in order to avoid the interferencce, which results in more order in the filter design. However, because of the limited Q values bandpass filters made of small sized ceramic resonators suffer from relatively large ripples at the band edges as the order of the filter increases. In order to compensate the large ripples while maintaining the sharp skirt frequency we propose a new RF amplitude equalizer. The equalizer made of two pole bandpass filter and an amplifier whose amplitude characteristics are the reverse of those of the bandapss filter. At the cellular band 9-pole bandpass filter with 10 MHz bandwidth exhibits 3 dB ripple when 8mm*8mm ceramic coaxial resonators are used. We added the RF equalizer to this filter and the flatness is improved as less than 1 dB.