• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1237-1242
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• 2016

In this paper, the low pass filter with harmonics suppression and rejection using parallel coupled-line and radial type open stub is presented. And the resultant characteristic of the proposed low pass filter is that the harmonics are suppressed and rejected in wide bandwidth due to the parallel coupled-line structure. The open stub of a low pass filter is constructed in radial type which can be used to adjust the size of filter. The size of the proposed low pass filter is $6.98{\times}7.60mm2$ and the cut off frequency is 2.45 GHz. And the filter is economical in unit cost and can be constructed easily and has the merit of mass product because the filter is composed of distributed element. Also, the widely rejected harmonics is 128 % in the bandwidth and the insertion and return losses of the low pass filter are 1.07 dB and 19.5 dB, respectively.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.138-141
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• 2001

In this paper, a VBF(variable bandwidth filter) is suggested and analyzed in time-frequency domain. There are four kinds of VBF, which are low-pass VBF, high-pass VBF, band-pass VBF and band-stop VBF. The proposed VBF can extract the components of signals within variable instantaneous bandwidth at a specific time instant. Instantaneous bandwidth is estimated in time-frequency domain. The VBF is represented by rational form in extended Fourier frequency domain.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.8
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• pp.82-88
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• 1998

We propose and design a new type of anrrow band-pass optical filter based on two fiber gratings with different reflection wavelength. The ripples occur in the spectra of the filter with two uniform fiber gratings. Our simulation results also show that the ripples disappear with the fiber gratings apodized to both gaussian and hyperbolic tangent function. The hyperbolic tangent function seems to be a better apodization function for improving the filter's performance in terms of narrow pass bandwidth and high transmission.

• Journal of Navigation and Port Research
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• v.30 no.7
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• pp.607-610
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• 2006

A new compact microstrip low-pass filter and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of low-pass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.79-84
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• 2006

A novel design of compact low-pass filter based on microstrip structure and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of low-pass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1077-1080
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• 2002

In building acoustics, reverberation time is an important acoustic parameter. However, it is often difficult to measure short reverberation times at low frequencies using the traditional band pass filter bank if the product of bandwidth (B) and reverberation time (T) is small. It is well known that the minimum permissible product of bandwidth and reverberation time of the traditional band pass filter is at least 16 ［F. Jacobsen, J. Sound Vib. 115, 163-170 (1987)]. This strict requirement makes it difficult to measure short reverberation times of an acoustic room at low frequencies exactly. In order to reduce this strict requirement, recently, the wavelet filter bank is developed and the minimum permissible product of bandwidth and reverberation time is replaced with 4 [S. K. Lee, J, Sound Vib. 252, 141-153 (2002)]. In the present paper, it is demonstrated how the short reverberation times at low frequencies are successfully measured by using the wavelet filter bank. In order to present this job, two synthetic signals and one measured signal are used for impulse responses of an acoustic room.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1991.10a
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• pp.119-122
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• 1991

In this paper, a new adaptive IIR notch filter employing all pass filter is proposed. Proposed all pass filter is composed of all pole and all zero sections, each of which utilizes modulation lattice filter [11]. And, adaption algorithm for proposed notch filter is also derived. In addition, the error surface for proposed IIR adaptive notch filter is analyzed. Computer simulation results reveal that the proposed adaptation algorithm works well for low SNR(signal to noise ratio) single and multiple sinusoids. And it is shown that for estimation time varying frequency, the parameter which is related to notch bandwidth is important than any other parameters.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.134-137
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• 2001

A variable bandwidth filter (VBF) is proposed for cleaning signals with known instantaneous bandwidth (IB). Also, the behaviors and the characteristics of the VBF are examined in time-frequency domain (TFD). The proposed VBF clips a noisy signal along the boundaries of IB and rejects noise in the outside of the IB of the signal in TFD. It is possible to construct four kinds of VBF that are low-pass VBF, high-pass VBF, band-pass VBF and band-stop VBF.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.357-360
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• 1999

A 20 MHz CMOS continuous low-pass filter using simulated floating inductor consisted of two fully-differential transconductors and a capacitor is presented. The theory of operation is described and simulation results show close agreement between predicted behaviour and experimential performance. Simulation results show that the filter has ripple bandwidth of 22 MHz, pass-band ripple of 0.36 ㏈. and cutoff frequency of 26 MHz at supplay voltage of $\pm$3 V. The power dissipation is 19.2 ㎽.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10A
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• pp.847-852
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• 2003

Apertures and PBG(Photonic Band Gap) has been employed on the ground plane in the coupled line filter simultaneously. In order to observe the maximum bandwidth, we used the line gap 0.2mm which is can be made in our lab. Band-pass filter type is four-stage coupled strip line filter. Teflon has been used for the substrate ($\varepsilon$$\sub$r/=3.2). The center frequency and the bandwidth are 2.18GHz and 230MHz, respectively. The bandwidth is broaden from 230MHz to 310MHz (80Mhz, about 34.7%) by aperture effect and harmonic frequencies are suppressed to 20-30dB by PBG effect. So the harmonic frequencies have been suppressed by the PBG effect and the bandwidth are broaden by aperture effect.