• Korean Journal of Optics and Photonics
• /
• v.13 no.1
• /
• pp.58-64
• /
• 2002

Using Mach-Zehnder type intensity modulator, we stabilized a 10 GHz harmonically mode-locked dispersion-compensated fiber ring laser using a feedback controlling system, and we measured its stability. The laser was stabilized for more than 16 hours by controlling the cavity length to suppress the relaxation oscillation frequency component which had caused the laser output instability. The ms timing jitter and ms amplitude noise were measured to be 260-524 fsec and 4~11.5%, respectively, and BER test measurement showed a value of 10$^{-13}$ .

• The Journal of the Acoustical Society of Korea
• /
• v.19 no.8
• /
• pp.26-34
• /
• 2000

This paper presents a new adaptive impulse noise cancelling technique based on the adaptive nonlinear suppressing function. The proposed "adaptive threshold algorithm (ATA)" is controlled by the normalized power prior input data term, and this adaptive threshold makes the cancelling system highly robust against additive impulse noise. For the performance evaluation, we have tested the proposed algorithm with the observed signals simulated in various impulsive noise environments and real EMG signals. As a result the proposed algorithm shows superior performance of 51.7% to the available techniques in the points of SNR and MSE.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.11B
• /
• pp.1841-1846
• /
• 2000

광대역 마이크로파 신호의 광전송시 변조과정에서 발생되는 상호잡음 성분의 억제를 위한 다단 직렬구조의 전계흡수 광변조기를 이용한 선형화 방법을 제안하였고 이론적으로 고찰하였다. 바이어스 전압에 따른 신호의 위상 반전이 발생되는 것을 이용하여 두 개의 서로 다른 바이어스 전압과 입력 마이크로파 신호의 전력 차를 이용하여 광대역 시스템의 성능을 좌우하는 IMD2와 IMD3를 동시에 억압시킬 수 있었다. 모의실험을 통하여 최적의 동작조건을 찾은 결과 35dB의 IMD2 억제와 50dB의 IMD3를 동시에 억압시킬 수 있었으며 이에 따라서 약 15dB의 동작영역의 증가를 얻을 수 있었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.6
• /
• pp.893-899
• /
• 2000

A 900 MHz low-noise amplifier(LNA) with a measured noise figure of 4.8 dB and an associated gain of 13.2 dB was fabricated in a 0.65 $\mu$m CMOS. The inductive source architecture of offers the possibility of achieving the best noise performance. At 900 MHz, the fabricated LNA dissipates 39 mW from a single 3 V power supply including the bias circuitry and provides -26dB input return loss, -17 dB output return loss, and an input 1-dB compression level of -12 dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.5
• /
• pp.513-520
• /
• 2003

In this paper, a novel design concept of frequency doubler using feedforward technique and DGS microstrip line is proposed. The feedforward loop plays a role of fundamental frequency suppression and DGS microstrip line suppresses over the 3rd order harmonic components. By using this new concept, the high suppression for the undesired signals could be achieved easily. The proposed technique is experimentally demonstrated in 1.87 GHz-to-3.74 GHz frequency doubler. The output power of -3 dBm at the frequency of 3.74 GHz(2f$\_$0/) is measured with 42.9 dB suppression of the fundamental frequency signal(f$\_$0/), 20.2 dB suppression of the 3rd harmonic signal(3f$\_$0/) and B9.7 dB suppression of the 4th harmonic signal(4f$\_$0/). The conversion loss of -2.34 dB ∼ -5.8 dB at the bandwidth of 100 MHz, the phase noise of -97.51 dB/Hz(＠10 kHz) were measured.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.4
• /
• pp.906-911
• /
• 2004

In this paper, a VCDRO(Voltage Control Dielectric Resonator Oscillator) applied to FMCW(Frequency Modulated Continuous Wave)Radar as stable source is implemented and constructed with a MESFET(Metal-semiconductor Field-Effect Transistor) for low noise, a dielectric resonate. of high frequency selectivity, and high Q varator diode to obtain a good phase noise performance and stable sweep characteristics. The designed circuits is simulated thrash harmonic balance simulation technique to provide the optimum performance. The measured result of a fabricated VCDRO shows that output is 2.22㏈m at 12.05GHz, harmonic suppression -30㏈c, phase noise -130㏈c at 100KHz offset, and sweep range of varator diode $\pm$18.7MHz, respectively. This oscillator will be available to FMCW Radar.

• Journal of Advanced Navigation Technology
• /
• v.6 no.1
• /
• pp.52-62
• /
• 2002

Electrical characteristics of two types of 20 GHz Push-Push GaAs MESFET dielectric resonator oscillators having Wilkinson and T-junction power combiners for the output stage have been investigated. The Push-Push oscillator for suppressing fundamental frequency 10 GHz and enhancing 20 GHz has been designed and realized in microstrip configuration on 20 mil thick RT-Duroid(${\varepsilon}_r$=2.52) teflon substrate. Two different types of power combiners, T-junction and Wilkinson, have been considered. Whenever one type of the combiners has been adopted for the output circuit, output power, phase noise and fundamental frequency suppression characteristics of the oscillator have been measured. When the Wilkinson power combiner was used, a maximum output power of 5.67 dBm, a phase noise of -105.5 dBc/Hz at an offset frequency of 100 kHz and a fundamental frequency suppression of -29.33 dBc have been measured. When the T-junction power combiner was used, a maximum output power of -1.17 dBm, a phase noise of -102.2 dBc/Hz at an offset frequency of 100 kHz and a fundamental frequency suppression of -17.84 dBc have been measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.3 s.118
• /
• pp.241-247
• /
• 2007

This paper introduces a new type push-push harmonic dielectric resonator oscillator. Proposed oscillators are utilized by HDRO(Harmonic Dielectric Resonator Oscillator) which are combined in push-push structure. As a result, fundamental signal suppression ratio and output power of harmonic signal has been improved. The increase of phase noise is compensated by improving coupling characteristic between resonator and parallel microstrip line. The proposed push-push HDRO shows the output power of 9.32 dBm, the fundamental signal suppression of -47.2 dBc and phase noise of -99.86 dBc at 100 kHz offset frequency and 18.7 GHz center frequency.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.11 no.2
• /
• pp.83-91
• /
• 2012

An RF energy detector for spectrum sensing in TV white space transceiver is presented. It is based on an RF active filtering technique that comprises a low-noise amplifier with a frequency-translation high-pass filtering feedfoward loop, which attenuates the unwanted sideband energy and only passes the wanted band energy. Unlike the conventional architecture, a new architecture that can attenuate both sidebands at the same time is proposed. A simplified system modeling method is presented to assess the non-ideality effects on the RF energy detector performances. System behavioral simulations demonstrate that the proposed architecture can be instrumental for realizaing a RF energy detector circuit in CMOS.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.9
• /
• pp.1277-1283
• /
• 2013

In this paper, a novel voltage controlled oscillator(VCO) using CSRR loaded microstrip line for X-band RADAR is proposed. Using the microstrip line loaded CSRR inserted between the oscillator and buffer to the filter, the harmonic suppression has been improved. The measured results of the fabricated oscillator shows that its oscillation frequencies are from 9.28 to 9.39GHz according to the tuning voltage 0~10V, its output power level are about 16.6dBm at 9.35GHz. Compared with VCO using the conventional VCO, VCO using CSRR loaded microstirp, the harmonic suppression characteristic has been improved in 10.4dB