• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.2
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• pp.109-116
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• 2022

In this paper, we propose a band rejection filter (BRF) with a state variable filter (SVF) structure to effectively remove the influence of 60 Hz line frequency noise introduced into the sensor system. The conventional BRF of the SVF structure uses an additional operational amplifier (OPAMP) to add a low pass filter (LPF) output and a high pass filter (HPF) output or an input signal and a band pass filter. Therefore, the notch frequency and the notch depth that determine the signal attenuation of the BRF greatly depend on the tolerance of the resistors used to obtain the sum or difference of the signals. On the other hand, in the proposed BRF, since the BRF output is formed naturally within the SVF structure, there is no need for a combination between each port. The notch frequency of the proposed BRF is 59.99 Hz, and it can be confirmed that it is not affected at all by the tolerance of the resistor through the Monte Carlo simulation results. The notch depth also has an average of -42.54dB and a standard deviation of 0.63dB, confirming that normal operation as a BRF is possible. Also, with the proposed BRF, noise filtering was applied to the electrocardiogram (ECG) signal that interfered with 60 Hz noise, and it was confirmed that the 60 Hz noise was appropriately suppressed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1255-1260
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• 2009

Microstrip interdigital filter is designed with the width and length of a resonator, the gap distance between resonators and the location of a tap. When designing filters, it is a benefit to design with few design parameters comparing to many design parameters. In this paper we design and implement two microstrip interdigital filters operating in the UWB(Ultra Wide-Band) frequency band, one using a fixed width of a resonator and the other using a different width of resonators. The test results of the implemented filters show that the low-band high filter with a fixed width has the insertion loss of 1.49dB, -10dB band width of 720MHz, -35.7dBattenuation at 4.8GHzand below -13dB of S11. The filter with a different width of resonators has the insertion loss of 1.6dB, -10dBbandwidth of 1.63GHz and below-8dBof S11.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2269-2274
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• 2015

In this paper, the reduced size in horizontal sizes of the narrow band pass filter (BPF) with λg/4 short stub using S shaped folded coupling structure is presented. This BPF with narrow bandwidth show flexible bandwidth with variation of the position of the stubs using the Qe(external quality factor) without changing the impedance value. On the other hand, by replacing the horizontal quarter-wavelength transmission lines with the equivalent S shaped coupled line, the BPF with reduced the size of horizontal can be realized. The proposed BPF shows the insertion loss of 1.46 dB and the return loss of 16.5 dB with bandwidth of 3.4 % at the center frequency of 5.8 GHz, respectively.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.776-779
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• 2004

A RF front-end module is designed for GIS(Gas Insulated Substation) which is employed for effective and efficient very high voltage transmission. Major advantage of the unit is improved PO detection sensitivity through minimizing the effect of surrounding interference signals, which is achieved by controlling the gain and the selection of the frequency band, for the precise detection of any UHF PO (Partial Discharge) disturbance occurred in the GIS due to some unwanted problems. For the development of the module, various switches for providing selected signal paths, wideband LNA, 3 BPF for selecting detection frequency band, and video detector are designed, fabricated and measured on 1 mm FR4 substrate with various RF components. The detection sensitivity of the unit was <-60 dBm that is sufficient to detect UHF PO signals as low as 1 pC. It is believed that the value is enough to detect the signal occurred in GIS.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.4 no.1
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• pp.31-36
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• 2005

In this paper, a planar type bandpass filter in multilayered PCB is presented. The multilayered PCB structure has some advantages on fabricating microwave devices such as the size reduction and ability of tight coupling by folding or embedding. The proposed BPF has two transmission zeros at the both sides of the center frequency by using independent electric and magnetic coupling structure. The designed BPF with four layer teflon PCBs of dielectric constant 2.94 has dimensions of 24x20x1.524 in mm, center frequency of 2.47GHz and bandwidth of about l00MHz. A good agrement is achieved between the measured result and the simulated one. The influences of air gaps between the layers are also analyzed and presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.347-353
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• 2018

In this paper, we studied a design method for a band-pass waveguide filter with a modified H-type resonant iris (RI) placed in a thin transverse wall of a rectangular waveguide. The horizontal straight gap at the center of a conventional H-shaped iris is modified to a U-shaped one to increase the equivalent capacitance, and the equivalent inductance is improved by changing the vertical two straight slots into C-shaped ones. From some simulation results for the frequency response of the proposed RI, it was observed that the proposed iris was advantageous for reducing its size and having better cutoff, compared to typical H-shaped one. Equivalent inductance, capacitance, and quality factor of the proposed RI were extracted to analyze its performance. A third-order band pass filter using the proposed modified H-shaped iris was designed and, it was observed that the filter operated in the frequency range of 9.18-9.84 GHz with its insertion loss of 0.3 dB and return loss of 14 dB.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.1
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• pp.41-47
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• 2011

Currently, there is widespread adoption of silicon-based technologies for the implementation of radio frequency (RF) integrated passive devices (IPDs) because of their low-cost, small footprint and high performance. Also, the need for high speed data transmission and reception coupled with the ever increasing demand for mobility in consumer devices has generated a great interest in low cost devices with smaller form-factors. The UWB BPF makes use of lumped IPD technology on a silicon substrate CSMP (Chip Scale Module Package). In this paper, this filter shows 2.0 dB insertion loss and 15 dB return loss from 7.0 GHz to 9.0 GHz. To the best of our knowledge, the UWB band-pass-filter developed in this paper has the smallest size ($1.4\;mm{\times}1.2\;mm{\times}0.40\;mm$) while achieving equivalent electrical performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.628-631
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• 2003

In this paper, 2.4 GHz WLAN BPF(Band Pass Filter) using LTCC(Low temperature cofiring ceramic) multilayer technology was simulated and manufactured. A modified ${\lambda}/4$ Hair-pin resonator with shunt-to ground loaded capacitor is used to shorten resonator length and improve circuit Q factor. Proposed BPF has a combline structure. Electro-magnetic Coupling between coupled strip-line resonators is controlled to provide attenuation poles at finite frequencies. The overall size of the filter is $3.2{\times}1.6{\times}1.3mm^3$. The measured result shows good agreement with simulated data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.147-152
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• 2005

In this paper, we have proposed a novel DGS(Defected Ground Structure) resonator and has designed the band -pass filter using the proposed ${\subset}$ stub-I type DGS resonator. This structure has strong advantages that can vary the retune loss at the passband freely and also can easily tune the attenuation pole frequency at the stopband. The bandpass filter can be made more smaller than the existing filters and be used to find the various applications for eliminating the harmonics and spurious mode at IMT-2000 band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1206-1211
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• 2006

In this paper, a Balun-BPF with the balun and BPF characteristics is proposed by using dual-mode ring resonator of $1{\lambda}$. We obtained the property of balun with the phase imbalance by symmetrically placing each output of ring resonator. The dual mode has been made by impedance difference between input and output lines. The fabricated Balun-BPF shows bandwidth of 40 MHz and insertion loss of 2.4 dB at a center frequency of 2.45 GHz. It shows the phase imbalance of $180{\sim}184$ degree and the magnitude imbalance of within 1 dB. The measured frequency responses agree well with simulated ones.