• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.1
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• pp.38-41
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• 1985

The hybrid design which is to take IIR filter of the first stage as a second order pole-zero model and minimize the filter length of the of the FIR filter of the following stage is presented. The outcome of the simulation showed us that the the filter length in the hybrid filters was remarkably decreased compared to that of the hybrid filters which take the IIR filter as a all-pole model. Although the hybrid filters couldn't obtain the exact linear phase. it was superior to the IIR filters in passband and stopband.

• ETRI Journal
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• v.19 no.2
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• pp.48-58
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• 1997

Using high quality high-$T_c$ superconducting (HTS) YBCO thin films, we designed and fabricated 3-pole, 5-pole, and 7-pole lowpass filters consisting of microstrip transmission lines and open-stub lines. We measured the microwave response of the filters in the temperature range of T=85 K to 27 K. AtT=30 K, the observed inband insertion loss was 0.14dB and 0.02dB for the 5-pole and 7-pole filters, respectively. The cut-off frequency was 4.7 GHz for the 5-pole filter and 7.9GHz for the 7-pole filter. To the authors' knowledge, the measured inband insertion losses are the best values reported so far for the open-stub line type HTS multipole lowpass filters. The skirt property of the 5-pole filter showed a large improvement over that of the 3-pole filter as predicted from the simulation. We found that, to obtain a stable performance, the HTS multipole lowpass filters should be operated at the temperatures between 60% and 70% of $T_c$.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.135-137
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• 2002

In the favor of adjusting microwave signal, Hairpin type Filter, which delay microwave signal enough to several nanosecond, is a key component. One of the main advantage in using Hairpin type Filter is a conveniency for equipping with Delay Module, and because of having a wide bandwidth, Hairpin type Filter can be designed to satisfy the most applications. In this work, we attempted to estimate the delay time in a superconductive hairpin type filter A software to synthesize even and odd order equiripple hairpin type filter has been developed. This software arbitrarily locate its transfer zeros making symmetric of asymmetric amplitude response and equalizing group delay. Borland C++ compiler has been used. The program was designed to run under MS-DOS, Window 98, Window 2000. The program optimizes the position of the transfer function zeros in order to fulfill the group delay specification masks. We designed and fabricated a hairpin type HTS 2-pole microstrip bandpass filter to operate at 5.8Ghz. The fabrication method was pulsed laser deposition and YBCO films were deposited on sapphire substrates with a Ce$O_{2}$ thin layer as a buffer layer. We also developed a new style hairpin type filter by using interdigitide inner-pole. Compared to the same size regular hairpin type filters, our filters had a lower center frequency.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1990-1992
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• 2003

This paper, Design formula of Bandpass Filter Using Inductive Coupled 2-pole SIR(Step Impedance Resonator) is supposed. General Filter Design Theory of Step Impedance Resonator is presented. Bandpass Filter using Inductive Coupled 2-pole SIR have been designed at 5.8Ghz band frequency for WLAN(Wireless Local Area Network). Simulation have used Circuit Simulation. We were showed excellent agreements between SR design theory and simulation results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.438-446
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• 2005

In this paper, the modified generalized Chebyshev rational function is presented. The new element values of prototype low pass filter are obtained by network synthesis using this rational function. This proposed filter has an equal ripple passband as same as conventional generalized Chebyshev filter, but unlike conventional filter which has only one attenuation pole at finite frequency, the proposed filter has two different from each other attenuation pole in stopband. If the harmonic frequency is set to the second attenuation pole frequency, this harmonic is suppressed efficiently. Furthermore, since the location of the second attenuation pole can be arbitrary adjusted. our filters are very available for the realization of wide stopband, particularly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.583-591
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• 2000

It this paper the multilayer chip band pass filter for next generation mobile communication phone is fabricated and designed. For the design the multilayer chip filter of non-contented equivalent circuit and contented equivalent circuit with attenuation pole is presented. Finally it is fabricated and designed using the multilayer chip filter of contented equivalent circuit with attenuation pole. The size insertion loss center frequency and band width of multilayer chip filter are 4.5$\times$3.2$\times$2.0[mm], 3.0[d.B] and 1945$\pm$25 MHz respectively. The multilayer chip filter was fabricated by screen printing with Ag electrode after tape casting. Simulation results of multilayer chip filter are compared with experimental results and found to be in excellent agreements.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.11
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• pp.627-634
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• 2000

In this paper, new micromachined tunble bandpass filters for multi-band millimeter-wave telecommunication systems are proposed. Two types of mm-wave tunable filters are fabricated using micromachning technology and the responses of the filters are measured. One is two-pole lumped elements filter and the other two-pole resonators filter. Frequency tunability of the filter is achieved by changing the gap between a common CPW ground plate and the movable cantilever beam connected to the transmission line with the controllable renge of 2.5${\mu}m$. The deflection of cantilever beam is measured with the applied DC voltage. With the applied bias voltage from 0 to 50 V, the fabricated filters show 0.6 GHz(2.3%) at 26.6 GHz, and 0.8 GHz(2.5%) at 32 GHz center frequency shift for the lumped elements and resonators filter, respectively. The life time of the fabricated gold cantilever structure are tested.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1251-1258
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• 1997

Generally, it is very important to study selective coupling between cavities of the filter structure using multimode cavity resonator. In this paper, we have manufactured 5-pole bandpass filter(BPF) using dual and triple-mode cavity resonator. To do so, we have derived the formulas for coupling coefficient about coupling between TE-modes from TM/TE-mode's tangential and lognitudinal field intensities each other. To implement the Chebyshev response, the intercabity slot combining dual-mode and triple-mode is designed to couple one H-field of TE-mode parallel to slot plate. In this paper, specially it is derived the formulas for T $E_{11p}$-mode from TE-modes, and determined after obtaining location and size of intercabity slot from the equation. In this ppaer, based on this result, we designed and implmented teh bandpass filter operated at the center frequency of 14.5GHz with a Chebyshev response. For the manufactured cavity filter, dual-mode and triple-mode cavity are resonted by two orthogonal T $E_{113}$-modes, and by two orthogonal T $E_{113}$-modes and one T $M_{012}$-mode, respecitively. The 2-stage 5-pole BPF proposed in this paper has the insertion loss of -2.32dB, the reflection loss of -15dB in the passband, and the out-or-rejection of -67dB.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.6
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• pp.300-305
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• 2004

In this paper, new design equations based on the pole-zero analysis for multi-layered interdigital stripline linear group delay bandpass filter with tap input ports are presented. As a design example, a four-pole group delay filter with center frequency of 2.14GHz, bandwidth of 160MHz, and group delay variation of $\pm$0.1nS for LTCC technology or multilayered PCB technology is designed. In the design process, it is not necessary to simulate the entire structure, as the simulation of half structures is sufficient. Good results can be attained after the optimizing process was performed three times using the proposed equations and a commercial EM simulator.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.35-39
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• 2000

Large-area high-temperature superconducting (HTS) films, filter design and damage-free processing technique have been developed to fabricate low insertion loss and sharp skirt filters. Further, long life cryocooler, low temperature low noise amplifier (LNA) and cryocable have been developed to assemble HTS filter subsystem for IS-95 and IMT-2000 mobile telecommunication. The surface resistance of the films was about 0.2 milli-ohm at 70 K, 12 GHz. An 11-pole HTS filter for IS-95 telecommunication system and a 16-pole HTS filter for IMT-2000 telecommunication system were designed and fabricated using 60 {\times}$ 50 mm$^2$ and one half of 3-inch diameter YBCO films on a 0.5-mm-thick MgO substrate, respectively. We have assembled the filter and low temperature LNA in a dewar with the cryocooler. Ultra low-noise (noise figure: 0.5 dB at 70 K) and ultra sharp-skirt (40 dB/1.5 MHz) performance was presented by the IS-95 filter subsystem and the IMT-2000 filter subsystem, respectively.