• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1254-1260
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• 2009

CDMA tele-Controller system is designed with a low power consumption 8 bit microcontroller, ATmega 2560. ATmega 2560 microcontroller consists of 4 UART (Universal asynchronous receiver/transmitter) ports, 4 kbytes EEPROM, 256 kbytes flash memory, 4 kbytes SRAM. 4 URAT is used for CDMA modem, communication for GPS module, EEPROM is used for saving a configuration for program running, a flash memory of 256 kbytes is used for storing a F/W(Firm Ware), and SRAM is used for stack, storing memory of global variables while program running. We have tested the communication distance between the coast station and sea by the fabricated control board using 800 MHz CDMA modem and GPS module, which is building for the navigational aid management system by remote control. As a results, the receiving signal strength is above -80 dBm, and then the characteristics of the control board implemented more than 10 km in the distance of the communication.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.4
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• pp.255-260
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• 1991

A voltage measuring system specified for the voltage fluctuation of the Pusan-Hamada submarine cable is developed by adding circuits of differential amplification and analog-to-digital conversion to a microprocessor-based data logger with a data modem. This system is charaterized by its small size. no power failure. fully unmanned operation. and precise instrumental drift correction. In addition to the cable voltage and current it measures an ambient temperature and a mercury cell voltage in order to calibrate temperature effect and check its long-term stability. The data acquired by this system show that the voltage signal. comprising fast random noises with a constant width of about 0.2V. fluctuates within a range of about 1V and the fluctuation frequency is similar to that of tidal motion. The source voltage of power feeding equipment (PFE) for the cable system seems to be affected when the room temperature changes rapidly.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.777-780
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• 2005

모바일 오디오 적용을 위한 저전력 ${\Sigma}{\Delta}$ Modulator 에 대한 설계와 layout 을 보였다. 전체 구조는 3 차 단일 피드백 루프이며, 해상도는 16bit 을 갖는다. 샘플링 주파수에 따른 Over-sampling Ratio 는 128(46kHz) 또는 64(96kHz) 가 되도록 하였다. 차동 구조를 사용한 3 차 ${\Sigma}{\Delta}$ modulator 내의 적분기에 사용된 Op-Amp 는 DC-Gain 을 높이기 위해서 Gain-boosting 기법이 적용되었다. ${\Sigma}{\Delta}$ modulator 의 기준 전압은 전류 모드 Band-Gap Reference 회로에서 공급이 되며, PVT(Process, Voltage, Temperature) 변화에 따른 기준 전압의 편차를 보정하기 위하여, binary 3bit 으로 선택하도록 하였다. DAC 에서 사용되는 단위 커패시터의 mismatch 에 의한 성능 감소를 막기 위해, DAC 신호의 경로를 임의적으로 바꿔주는 scrambler 회로를 이용하였다. 4bit Quantizer 내부의 비교기 회로는 고해상도를 갖도록 설계하였고, 16bit thermometer code 에서 4bit binary code 변환시 발생하는 에러를 줄이기 위해 thermometer-to-gray, gray-to-binary 인코딩 방법을 적용하였다. 0.18um CMOS standard logic 공정 내 thick oxide transistor(3.3V supply) 공정을 이용하였다. 입력 전압 범위는 2.2Vp-p,diff. 이며, Typical process, 3.3V supply, 50' C 시뮬레이션 조건에서 2Vpp,diff. 20kHz sine wave 를 입력으로 할 때 SNR 110dB, THD 는 -95dB 이상의 성능을 보였고, 전류 소모는 6.67mA 이다. 또한 전체 layout 크기는 가로 1100um, 세로 840um 이다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.5
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• pp.143-152
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• 2004

A novel low-power wideband bipolar second-generation current conveyors(CCIIs) and its application to universal instrumentation amplifier(UIA) were proposed. The CCII for accuracy voltage or current transfer characteristics and low current input impedance adopted adaptive current bias circuit into conventional class Ab CCII. The UIA consists of only two CCIIs and four resistors. Three instrumentation function of the UIA can be realized by selection of input signals and resistors. The simulation results show that the CCII has input impedance of 2.0$\Omega$ and the voltage gain of 60㏈ for frequency range from 0 to 50KHz when used as a voltage amplifier. The CCII has also good characteristics of current follower for current range from -100㎃ to ＋100㎃. The simulation results show that the UIA has three instrumentation amplifier functions without resistor matching. The UIA has the voltage gain of 40㏈ for frequency range from 0 to 100KHz when used as a fully-differential instrumentation amplifier. The power dissipations of the CCII and the UIA are 0.75㎽ and 1.5㎽ at supply voltage of $\pm$2.5V, respectively.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.2
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• pp.161-166
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• 2014

This Electromagnetic metal piece detection sensor, having high sensitivity even under high humidity and dust density, using LVDT was investigated. Metal detection characteristics using phase detection method, for 3 frequencies covering ELF and LF band, were experimentally measured. It was found that the sensitivity for metal and animal food, in which metal piece was included, was exponentially increased as frequency increased. Reducing cutoff frequency of LPF after PD was found to be effective to proportionally increase sensitivity. Also the sensitivity of metal piece detection was enhanced by optimizing BPF bandwidth and SNR. Metal piece detection limit using available ferrous test samples was found to be 0.7mm diameter from the experiment using 50kHz, in ELF band, which was known to have better selectivity to animal food. is an example of ABSTRACT format.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6804-6809
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• 2014

This paper presents a bandpass filter using a current differencing transconductance amplifier (CDTA)s for application to low-voltage and low-power analog signal processing systems. The presented filter employs grounding and floating active inductors, which are composed of two or three CDTAs, and is capable of realizing all the standard functions of the filter without requiring any component matching criteria or extra active components. The HSPICE simulation result of the designed active bandpass filter showed that it had a 10MHz center frequency with -2.5dB attenuated bandwidth from 9.5 MHz to 10.5 MHz, and -50dB from 8 MHz to 17 MHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.497-502
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• 2007

Broadband monolithic SiGe HBT variable gain amplifier with a feedforward configuration have been newly developed to improve bandwidth and dB-linearly controlled gain characteristics. The VGA has been implemented in a $0.35-{\mu}m$ BiCMOS process. The VGA achieves a dynamic gain-control range of 19.6 dB and a 3-dB bandwidth of 4 GHz ($4{\sim}8\;GHz$) with the control-voltage range from 0.6 to 2.6 V. The VGA produces a maximum gain of 9.3 dB at 6 GHz and a output power of -3 dBm at 8 GHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.1
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• pp.79-87
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• 2013

A new modulation technique - correlative encoded FSK (CEFSK) - for use in power and bandwidth limited digital communication system is proposed. CEFSK is free of ISI and generates output signals which have a smooth and continuous phase transition and a reduced envelope fluctuation by keeping correlation between amplitude and phases of two subsequent symbols. In comparison to conventional one-bit differential detected (1DD) GFSK, the performance of the 1DD-CEFSK in a non-linearly amplified (NLA) channel impaired by additive white Gaussian noise (AWGN), ISI and IM, is analyzed via computer simulation. The simulation result shows that, in an NLA single-channel, 1DD-CEFSK provides a signal-to-noise ratio (SNR) advantage of up to 1.2dB and 0.8dB at BER of $1{\times}10^{-4}$ when input back-off (IBO) of HPA is -1.0dB and -3.0dB, respectively. For the same channel environment with multi-channel, 1DD-CEFSK outperforms 1DD-GFSK by 1.1dB in SNR, regardless of the value of IBO.

• The Journal of the Acoustical Society of Korea
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• v.35 no.5
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• pp.368-374
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• 2016

This paper presents constructing transmitter and receiver by using a direct sequence spread spectrum techniques to DPSK (Differential Phase-Shift Keying) scheme in underwater acoustic communication. Since DPSK signal can be demodulated if the receiver knows only the phase difference between the adjacent bits, DPSK receiver structure has the advantage of being simplified. In the conventional receiver, two adjacent symbols of transmitted signal before despread are passed to the transition correlator that detects data by comparing maximum correlation outputs. At this time, the error for maximum value of the correlator output may increase because of low SNR (Signal to Noise Ratio) or high Doppler shift frequency according to the underwater channel. In this paper, we propose a method for accurate detection result using the width as well as the magnitude among outputs produced by the correlator. The performances of the proposed method was evaluated by simulation and lake trial data.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.71-79
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• 2013

This paper describes a 12.5 Gb/s low-power receiver design with equalizer adaptation. The receiver adapts to channel and chip process variation by adaptation circuit using sampler and serializer. The adaptation principle is explained. It describes technique receiving ground referenced differential signal of voltage-mode transmitter for low-power. The CTLE(Continuous Time Linear Equalizer) having 17.6 dB peaking gain to remove long tail ISI caused channel with -21 dB attenuation. The voltage margin is 210 mV and the timing margin is 0.75 UI in eye diagram. The receiver consumes 0.87 mW/Gb/s low power in 45 nm CMOS technology.