• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.941-944
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• 2000

This paper proposes, for the first time, the design of class I pull-push power amplifier. With the new design, the output power is increased by four times when compared to conventional single-end class I connection amplifier with the same supply voltage. The performance of the proposed amplifier is verified by with a 100-kHz power amplifier constructed using general-purpose NPN transistors.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.218-221
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• 2000

The electronystagmography(ENG) means to measure and record CRP(Corneal-Retinal Potential) whenever the eyeball is moved by using a skin electrode stuck to the hi-temporal and the difference of CRP. Both the horizontal and vertical movement are known according to the position of the stuck skin electrode. In this paper, the variable time-constances to record the eyeball signal of the conventional EOG(Electro-Oculograph) Amplifier is chosen. The shorter the time-constance is, the worse the distortion of a signal is. But the unbalanced impedance of the electrode stuck on the hi-temporal is reduced. Also, the longer the time-constance is, the less the distortion of it signal is. But it is sensitive to the change of base line according to the unbalanced impedance. In order to solve these problems, an DC-Amplifier, the distortion of the eyeball signal is globally used. By solving unbalanced impedance problem of EOG amplifier, the distortion ratio of EOG amplifier is improved.

• ETRI Journal
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• v.31 no.2
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• pp.234-236
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• 2009

We present a novel operational amplifier preset technique for a switched-capacitor circuit to reduce the acquisition time by improving the slewing. The acquisition time of a variable gain amplifier (VGA) using the proposed technique is reduced by 30% compared with a conventional one; therefore, the power consumption of the VGA is decreased. For additional power reduction, a programmable capacitor array scheme is used in the VGA. In the 0.13 ${\mu}m$ CMOS process, the VGA, which consists of three-stages, occupies 0.33 $mm^2$ and dissipates 19.2 mW at 60 MHz with a supply voltage of 1.2 V. The gain range is 36.03 dB, which is controlled by a 10-bit control word with a gain error of ${\pm}0.68$ LSB.

• The Journal of the Acoustical Society of Korea
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• v.19 no.1E
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• pp.22-26
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• 2000

In this paper, the DS/CDMA PN code acquisition system with nonlinear transmitter power amplifier based on digital matched filter (DMF) which has the rapid acquisition time is presented and the performance is evaluated in terms of mean acquisition time, detection probability, and signal to interference under multiuser environment. The performance is presented with respect to the output backoff of the nonlinear amplifier and the correlation window.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.409-412
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• 2000

A high performance EEG signal measurement system is fabricated. It consists of high precision pre-amplifier and auto identification bandwidth unit. High precision pre-amplifier is composed of signal generator, signal amplifier with a impedance converter, body driver and isolation amplifier. The pre-amplifier is designed for low noise characteristics, high CMRR, high input impedance, high IMRR and safety, Auto identification bandwidth unit is composed of AD-converter and PIC micro-controller for real time processing EEG signal. The performance of EEG signal measurement system has been shown the classified bandwidth through the clinical demonstrations.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.538-541
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• 1998

This paper describes the development of 5.15ns 32kb asynchronous CMOS SRAM using 0.6.mu.m CMOS technology. The proposed high speed embedded SRAM is realized with optimized control circuit and sense amplifier at a power supply of 3V. Using proposed control circuit, the delay time from address input to wordline 'on' is reduced by 33% and mismatch-insensitive sense amplifier can sense a small difference of bit-line voltage fast and stably.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.66-73
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• 2007

The various output characteristics of a pulsed Ti:sapphire laser oscillator with a plane-parallel resonator, pumped longitudinally by the second harmonic wave of a Nd:YAG laser, and the output of a Ti:sapphire laser amplifier operated along the single path of the oscillator beam were investigated and analyzed. In the case of the oscillator, we measured the spectrum, the pulse buildup time, the temporal duration time of the pulse, and the output energy according to the variation of the pumping energy, resonator length, and the reflectance of the output coupler. And, in the case of the amplifier, we investigated and analyzed the output energy of the amplifier as a function of the time difference between the two pump beams of the oscillator and the amplifier, the pumping energy of the oscillator, and the pumping energy of the amplifier When pump energies of both the oscillator and the amplifier were 18 mJ/pulse, we could find that the output energy of the amplifier increased linearly and gradually up to the time difference of 35 ns. Finally, we determined that the slope efficiencies of the oscillator and the amplifier were 23.5 % and 11.6 %, respectively.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.469-472
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• 2004

In this paper a current mode sense amplifier suitable for 30nm SONOS flash memories read operation is presented. The proposed sense amplifier employs cross coupled latch type circuit and current mirror to amplify signal from selected memory cell. This sense amplifier provides fast response in low voltage and low current dissipation. Simulation results show the sensing delay time and current dissipation for power supply voltages Vdd to expose limitations of the sense amplifier in various operating conditions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.349-352
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• 2001

The transient response in TDFA(Thulium-Doped Fiber Amplifier) is theoretically investigated. The TDFA has the spectral gain band in 1.47 ${\mu}{\textrm}{m}$. The transient model includes the transient buildup of the population inversion, the pump power, the signal power and their transient variation along the fiber amplifier. The results of numerical analysis can predict the gain saturation and recovery time at the fiber amplifier. It also shows the gain saturation and recovery effect depending on the pumping and saturation rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.3
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• pp.459-463
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• 2002

We studied the effect of gain recovery at the optical fiber amplifier by the input pulse trains We also theoretically analyzed the limitation of the saturation and recovery time for the PDFA(Praseodymium-Doped Fiber Amplifier) which has the spectral gain at 1.3${\mu}{\textrm}{m}$ band. We can predict the interval between the pulse train, pump power, and the effect of the saturation and recovery time which is affected to the amplification of the optical pulse.