• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.886-893
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• 2004

In this paper, active resonator oscillator using active band pass filter with gain, active resonator with negative resistance using transistor(agilent ATF-34143) is designed and fabricated. Proposed active resonator oscillator for local oscillator in ISM band(5.8GHz) is designed with 5.5 GHz oscillation frequency. Designed active resonator oscillator implemented on the substrate which has the relative dielectric constant of 3.38, the height of 0.508mm, and metal thickness of 0.018mm. Active resonator oscillators using active band pass filter with gain show the oscillation frequency of 5.6GHz with the output power of -2dBm and phase noise of -81dBc/Hz at the offset frequency of 100kHz. Active resonator oscillators active resonator with negative resistance show the oscillation frequency of 5.6, 5.8GHz with the output power of -4dBm and phase noise of -91dBc/Hz at the offset frequency of 100kHz.

• 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 ㎽.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.142-143
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• 2003

EDFA의 이득(gain)과 잡음지수(noise figure)는 매우 중요한 특성 중의 하나이다. 전송 시스템에서 필연적으로 발생하는 ASE 잡음을 제거하는 것이 중요하다. EDFA의 중간에 필터(filter)와 아이솔레이터(isolator)를 삽입하여 불필요한 ASE를 제거함으로써 이득과 잡음지수를 향상시킬 수 있으며, 기존의 단일경로(single-pass) EDFA에서 필터의 위치가 40-60％ 근처에서 이득과 잡음지수 향상이 가장 크게 된다. 그러나, 거울(mirror)을 사용하여 증폭 효율을 높인 이중경로(double-pass) EDFA에서 필터에 의한 이득 향상에 관한 연구발표는 아직까지 없다. (중략)

• Journal of the Microelectronics and Packaging Society
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• v.10 no.1
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• pp.19-24
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• 2003

A very small size 2.4 GHz ISM band BPF(Band Pass Filter) is realized using LTCC Multi-layer technology. Proposed design method enables to achieve BPF size $2.0\times1.2\times0.8mm^3$. A $lambda/4$ resonator with shunt-to-ground loaded capacitor is used to shorten resonator length, achieving higher quality factor. Also this resonator enables BPF to improve out-of-band rejection. Coupling coefficients between coupled strip-line resonators and external quality factor (Qe) of a resonator are derived and applied to the filter design. The measured results show good agreement with simulated data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.599-609
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• 2000

In this paper, sub-harmonically pumped single balanced resistive mixers are presented . Frequency bandwidth is selected for a Ku-band, which is 11.75-12.25GHz for RF, 5.375∼5.625 GHz for LO, and 1 GHz for IF signals. A rat-race hybrid is designed for the accomplishment of single balanced type. A low pass filter (LPF) with photonic band gap(PBG) structure is used for good conversion loss and unwanted harmonics suppression. Two types of mixers are suggested, which are one with no gate bias for no DC power consumption and the other with the IF amplifier for conversion gain. When a LO signal with the power of 6 dBm at 5.5 GHz is injected, a conversion loss of 12.17dB and a conversion gain of 7.83 dB are obtained for each mixer. For the both mixers , LO to RF isolation of 20 dB and LO to IF isolation of 60dB are obtained. With the RF power of -30dBm to -3dBm, the mixer shows linear characteristics region of IF. this mixer can be applied for Ku-band and other microwave communication systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6A
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• pp.547-555
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• 2006

We implemented DPU(Double-Pass Gain-Clamped) L-band EDFA for highly efficient amplification. A lasing signal generated within the linear cavity, can minimize the fluctuation of surviving channels when several WDM(Wavelength Division Multiplexing) channels are added or dropped. The new method measuring the characteristics of transient response of surviving channels quantitatively is suggested. It is to measure the ratio of lasing output before add or drop to that after add or drop. We investigated dynamic characteristics by using this method according to lasing wavelengths and propagation directions within the cavity. Experimental measurements show that the short lasing wavelength and backward propagation direction is the best condition for small fluctuation of surviving channels.

• The Journal of the Acoustical Society of Korea
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• v.43 no.4
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• pp.406-413
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• 2024

The proposed method uses Generalized Cross Correlation - Phase Transform (GCC-PHAT) method with nonlinear preprocessing and a frequency domain low-pass filter. In this paper, by reinterpreting the calculation process of GCC-PHAT as DFT, we derive that there is an effective frequency band used for time delay estimation in GCC-PHAT, and by using only the effective band using a low-pass filter, the noise component is reduced and it improvesthe time delay performance in impulsive noise environments. By comparing the proposed method with the traditional GCC-PHAT in an impulsive noise environment, we show that the GCC-PHAT becomes more robust to the impulsive noise.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.3
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• pp.59-64
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• 2002

In the RFID system using ISM-band, The tag mounted at the object has used the DC power by rectifying the RF signals of the small antenna for operating the micro-controller and memory. The performance of the tag would be reduced because of the second harmonics generated by the nonlinearity of the semiconductor and the spurious signal excited the high order mode of the antenna. This paper has realized the novel type low-pass filter with "the Stub-I type DGS slot structure" to improve the efficiency of the tag by suppressing the harmonics. The optimized frequency character at the pass-band/stop-band has obtained by tuning the stub width and slit width of I type slot. The measured result of the LPF has the cutoff frequency 3.25 GHz, the insertion loss about -0.29~-0.3 dB at pass-band 2.4 GHz~2.5 GHz, the return loss about -27.688~-33.665 dB at pass-band with a good performance, and the suppression character is about -19.367 dB at second harmonics frequency 4.9 GHz. This DGS LPF may be applied the various application as the RFID, WLAN to improve the efficiency of the system by suppressing the harmonics and spurious signals. 

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.616-622
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• 2018

Energy which is released by a huge earthquake can reach the ionosphere and induce disturbances. Those disturbances can detected by analyzing the global navigation satellite system (GNSS) satellite's signal. For detecting those disturbances, band-pass filter is generally used. Therefore, it is important to select proper pass band that can contain disturbance's frequency. In this paper, we analyzed a frequency of the ionospheric disturbances which are induced by earthquake by using GNSS signal. For analyzing seismogenic ionospheric disturbances, we calculated a geometry free combination of carrier phase to obtain a ionospheric delay. After that, the fast Fourier transform was applied to the 1 mHz high-passed ionospheric delay. As a result of analyzing disturbances, the frequency band of earlier disturbances was 4.5 mHz~11mHz and the representative frequency was 5.7 mHz. The frequency band of subsequent disturbances was 6 mHz~10 mHz and the representative frequency was 7.3 mHz.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.32-37
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• 2010

The algorithm of multiple channel signal processing requires the flexibility of variable frequency band, efficient allocation of transmission power, and flexible frequency band reallocation to satisfy various service types which requires different transmission rates and frequency band. There are three methods including per-channel approach, multiple tree approach, and block approach performing frequency band reallocation method by channelization and dechannelization in the multiple-channel signal. This paper proposes an improved per-channel approach for converting the frequency band of multiple carrier signals efficiently. The proposed algorithm performs decimation and interpolation using CIC(cascaded integrator comb filter), half-band filter, and FIR filter. In addition, it performs filtering of each sub-channel, and reallocates channel band through FIR low-pass filter in the multiple-channel signal. The computer simulation result shows that the perfect reconstruction of output signal and the flexible frequency band reallocation is performed efficiently by the proposed algorithm.