• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.138-143
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• 2009

In this paper, a novel ultra-wide band filter which is operating at frequency bands from 3.1 GHz to 10.6 GHz is suggested. It is modified from the conventional ring filter and consisted of a ring with two parallel open-stub with length of ${\lambda}/8$. It improves the sharpness of the conventional ring filter and is compact. The measured results show that the fabricated filter has a insertion loss of 2.1 dB and the measured group delay of the filter is less than 463 ps through UWB frequency bands.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.35-37
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• 2001

다층 인쇄 회로 기판에 Combline 구조를 가진 스트립 라인 또는 마이크로 스트립 라인 대역통과 필터를 구현하였다. 저 비용 구현과 이동성과 휴대성을 강조하기 위해 기존의 세라믹 대신 FR4 와 에폭시를 기반으로 하는 다층 회로 기판의 도체 층에 집적화하였다. Combline 각 끝단에 커패시터를 부하 함으로써 전기적 길이를 화장하였고 전체적인 크기를 감소시킴으로서 적당한 필터 특성을 얻을 수 있었다. 구현된 필터는 마이크로파 대역에서 사용 가능하며 특히 Bluetooth나 Wireless LAN 과 같은 ISM 대역을 사용하는 무선통신소자로서 사용 가능하다.

• The Journal of the Acoustical Society of Korea
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• v.19 no.3
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• pp.63-71
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• 2000

A new type of second-order digital peaking filters for professional-quality digital audio system is proposed whose frequency response can be elaborately controlled throughout the composite structure of a standard band-pass filter and a 0-dB bypass gain. The proposed method for designing the peaking filter uses the Q-compensation technique to prevent the Q-distortion caused by the variation of the gain factor and is reduced into a compact form which is proper to the real-time implementation. Methods are examined for computing its coefficients, which are exact and very straightforward to compute with small amount of the system resources.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.4
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• pp.585-590
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• 1993

A wide passband filter consisting of 3-stage ssymmetrical coupler can be realized, where the admittance inverter parameters in equivalent circuit of asymmetrical coupled microstrip lines are given as a function of a fundamental design parameter of a bandpass filter. An experimental filter was designed over 22 percend bandwidth centered at 9GHz and optimized using Super-Compact. Measured forward transmission and forward reflection closely matched design data but measured insertion loss was slightly higher (0.7dB) than the designed value.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.578-581
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• 2004

유전체가 삽입된 공동 공진기는 유전체에 대부분의 전자계가 집속되어 있기 때문에, 도체 손실이 매우 적고 높은 Q값과 온도 안정성이 뛰어나다. 동일한 주파수에서 동작하는 다른 필터에 비해 상대적으로 작기 때문에 소형화에도 적합하다. 본 논문에서는 유전체가 삽입된 공동 공진기의 전자기 분포와 특성을 수치해석과 HFSS(High Frequency Structure Simulator)를 이용하여 분석하였고 이 결과를 토대로 HFSS를 이용한 순차적 방법을 도입하여 4-pole 이중모드 대역통과 필터를 설계, 제작하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.200-207
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• 2009

This paper presents a compact, low insertion loss, sharp rejection and wide band microstrip band pass filter that is composed rectangular loop resonator and Step-Impedance-Open-Stub(SIOS). The SIOS can be reduce length about 30 % more than general 0.25 $\lambda$ open stub. And the stub can the advantage of tuning impedance magnitude. In order to demonstrate agrement of this paper prove, the optimized wide band pass filters are realized and experimented. A transmission line model used to calculate the frequency response of the new filters shows good agreement with measurements. The filter has 3 dB fractional bandwidth of 51.75 %(3.206 GHz), an insertion loss of better than 0.44 dB from 4.587 GHz to 7.793 GHz, and two rejection of greater than 30 dB within 221 MHz($4.326{\sim}4.587\;GHz$) at low frequency band, 181 MHz($7.739{\sim}7.954\;GHz$) at high frequency band. Maximum rejection characteristics of the filter are -61.8 dB at low frequency and -76.3 dB at high frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7C
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• pp.658-666
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• 2007

In general, the earlier linear-phase MAXFLAT(maximally flat) lowpass FIR filters have the main disadvantage of a gain response in the half frequency band $(0{\leq}w{\leq}{\pi}/2)$ by the closed form transfer functions used in design techniques for realizing them. Moreover, most of them has existent problems as follows : ripple error in the stopband, gentle-cutoff attenuation, phase and group delay and inexact cutoff frequency response. It is due to the approximation algorithms such as Chebyshev norm and Remez exchange which are used to approach MAXFLAT and linear-phase characteristics in frequency domain. In this paper, a new mathematically closed-form transfer function is introduced for the design of MAXFLAT lowpass FIR filters which have the zero-phase and wideband-gain response. In addition, we verify that the closed-form transfer function is easily realized due to our generalized formulas derived newly by using MAXFLAT conditions including an arbitrary cutoff point. This method is, therefore, useful for "simple and quick designs". Conclusively, we propose a technique for the design of new zero-phase wideband MAXFLAT lowpass FIR filters which can achieve sharp-cutoff attenuation exceeding 250 dB almost everywhere.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.6
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• pp.8-12
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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 band-pass section combined with a band-rejection section based on two different coupled rings. The sideband region of the transfer characteristics of the first band-pass filter section was selectively suppressed by means of the band-rejection section without causing any excessive insertion loss. As a result, the overall transfer characteristics of the proposed filter was unproved so that its sideband suppression was elevated to allow for sharper roll-off and narrower bandwidth. In this work, a conventional single-ring band-pass filter and a proposed filter including the band-rejection section were designed and fabricated. As for the achieved device performance, with the center frequency at about 4 GHz, the sideband suppression ratio was increased as much as 8 dB and the 3-dB 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%.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.155-160
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• 2003

Owing to the advances in ADC and DSP technologies, signals in If band, which once had to be processed in analog technology, can new be digitally processed. This is referred to as "Digital IF" or "Digital Radio", which is a preliminary stage of SDR. Applying the digital radio technology to a multi-carrier receiver design, a processing gain is generated through an over-sampling of input data. In the digital receiver, decimation is performed for reducing the computational complexity CIC and half band filter is used together with the decimation as an anti-alising filter. The CIC filter, however, should introduce the roll-off phenomenon in the passband, which causes the receiving performance to be considerably degraded due to the distorted Passband flatness of receiving filter. In this paper, we designed a CIC roll-off compensation filter for W-CDMA digital receiver. The performance of the proposed compensation filter is confirmed through computer simulations in such a way that the BER is minimized by compensating the roll-off characteristics.off characteristics.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1992.06a
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• pp.379-383
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• 1992