• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.84-87
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• 2006

본 연구는 Current Mirror에 있어서 Active Current Bias에 관하여 기술하였다. Current mirror에서 Active Current Bias를 걸어주는 보편적인 방법은 Current Bias단에 저항을 연결하여 저항값을 조절함으로 해서 Current를 제어하는 방법을 사용한다. Reference 전류를 제어하는데 있어 새로이 제안하는 것은 Flyback Converter를 이용하여 Acitve Current Bias를 제어 하려 한다. 트랜지스터를 이용하여 Current Mirror Circuit를 구성하고 Current Bias 측에 Flyback Converter Circuit을 연결한다. Flyback Converter의 PWM의 Duty Ratio를 조절함으로 해서 전류를 제어하는 특징을 이용하여 Active Current Bias를 제어한다.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1650-1660
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• 2016

This paper proposes a compensator to eliminate the DC bias of inductor current. This method utilizes an average-current sensing technique to detect the DC bias of inductor current. A small signal model of the DC bias compensation loop is derived. It is shown that the DC bias has a one-pole relationship with the duty cycle of the left side leading lag. By considering the pole produced by the dual active bridge (DAB) converter and the pole produced by the average-current sensing module, a one-pole-one-zero digital compensation method is given. By using this method, the DC bias is eliminated, and the stability of the compensation loop is ensured. The performance of the proposed compensator is verified with a 1.2-kW DAB converter prototype.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.635-636
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• 2006

A self-biased CMOS current reference is described which provides supply and temperature independent bias current. The supply independency is obtained by subtracting two bias currents which have the same supply dependency. Unlike the conventional self-bias CMOS current reference, excellent supply independency can be obtained even with the minimum channel length devices and thus smaller area implementation becomes possible. The supply independent bias current is then applied to a temperature compensating circuit and as a result supply and temperature independent bias current is obtained. The current reference has been implemented in a $0.25{\mu}m$ standard CMOS technology. The active silicon area is only $45{\mu}m{\times}45{\mu}m$. The simulated temperature coefficient is 64ppm/$^{\circ}C$ in temperature range between $0^{\circ}C$ and $120^{\circ}C$. Supply voltage can be as low as 1.3V and the supply dependency of the current reference is measured to be smaller than 4500ppm/V. While providing $10.25{\mu}A$ output current, the current reference consumes $160{\mu}W$.

• Journal of Surface Science and Engineering
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• v.50 no.5
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• pp.398-404
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• 2017

In order to study the AC driving mechanism for OLED lighting, the fluorescent OLEDs were fabricated and the electroluminescent characteristics of the OLEDs by AC forward bias were analyzed. In the case of the driving method of OLED by AC forward bias under the same voltage and the same current density, degradation of luminescent characteristics for elapsed time progressed faster than in the case of the driving method by DC bias. These phenomena were caused by the peak voltage of AC forward bias which is ${\sqrt{2}}$ times higher than the DC voltage. In addition, the degradation of the OLED was accelerated because the AC forward bias had come close to the upper limit of the allowable voltage range even though the peak voltage didn't exceed the allowable range of the OLED. However, the fabricated fluorescent OLED showed little degradation of OLED characteristics due to AC forward bias from 0 V to 6.04 V. Therefore, OLED lighting by AC driving will become commercialized if sufficient luminance is realized at a voltage at which the characteristics of the OLED are not degradation by the AC driving method.

• Current Optics and Photonics
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• v.4 no.4
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• pp.273-276
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• 2020

We report on the relationship between output current for quadrant photodetector (QPD) and bias voltage in silicon-based p-i-n (positive-intrinsic-negative) QPD examined using millisecond pulse laser (ms pulse laser) irradiation. The mechanism governing the relationship was further studied experimentally. The output current curves were obtained by carrying out QPD under different bias voltages (0-40 V) irradiated by ms pulse laser. Compared to other photodetectors, the relaxation was created in the output current for QPD which is never present in other photodetectors, such as PIN and avalanche photodetector (APD), and the maximum value of relaxation was from 6.8 to 38.0 ㎂, the amplitude of relaxation increases with bias value. The mechanism behind this relaxation phenomenon can be ascribed to the bias voltage induced Joule heating effect. With bias voltage increasing, the temperature in a QPD device will increase accordingly, which makes carriers in a QPD move more dramatically, and thus leads to the formation of such relaxation.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.9
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• pp.56-64
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• 1992

Because of a small bandgap energy, a high doping density, and a low operating temperature, the dark current in HgCdTe photodiode is almost composed of a tunneling current. The tunneling current is devided into an indirect tunneling current via traps and a band-to-band direct tunneling current. The indirect tunneling current dominates the dark current for a relatively high temperature and a low reverse bias and forward bias. For a low temperature and a high reverse bias the direct tunneling current dominates. In this paper, to verify the tunneling currents in HgCdTe photodiode, the new tunneling-recombination equation via trap is introduced and tunneling-recombination current is calculated. The new tunneling-recombination equation via trap have the same form as SRH (Shockley-Read-Hall) generation-recombination equation and the tunneling effect is included in recombination times in this equation. Chakrabory and Biswas's equation being introduced, band to band direct tunneling current are calculated. By using these equations, HgCdTe (mole fraction, 0.29 and 0.222) photodiodes are analyzed. Then the temperature dependence of the tunneling-recombination current via trap and band to band direct tunneling current are shown and it can be known what is dominant current according to the applied bias at athe special temperature.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.5
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• pp.198-201
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• 2005

Carbon nanofibers were formed on silicon substrate which was applied by negative direct current (DC) bias voltage using microwave plasma-enhanced chemical vapor deposition method. Formation of carbon nanofibers were varied according to the variation of the applied bias voltage. At -250 V, we found that the growth direction of carbon nanofibers followed the applied direction of the bias voltage. Based on these results, we suggest one of the possible techniques to control the growth direction of the carbon nanofibers.

• Journal of the Korean Magnetics Society
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• v.23 no.3
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• pp.94-97
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• 2013

Orthogonal fluxgate sensor was fabricated with cylinder-shaped NiZn ferrite core, Cu wire through the core and pickup coil wound on the core, and the bias current effect on the output sensitivity of it was investigated. The output ($$\sim_\sim$$ sensitivity) of the sensor was largely dependent on the operation frequency, and the tendency of sensor output was similar to that of the impedance of pickup coil. The maximum output was obtained by adding the DC bias current of which value was over 50% of the excitation current. The output was saturated when the DC bias current was larger than 50% of the excitation current.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.8
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• pp.706-710
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• 2008

The substrate bias effect on the current level of SOI-MOSFETs for high temperature operation has been investigated. In this work, we demonstrate the current level of SOI-MOSFETs can be controlled at different temperatures by applying a control bias to the substrate, showing that all current levels below T=150$^{\circ}C$ can be adjusted to a constant current level. 2D numerical simulation results show that substrate bias effectively controls the current conduction; as the substrate bias effectively lower the potential of the channel, inversion carrier generation is effectively controlled and consequently a constant current conduction level is achieved up to T=150$^{\circ}C$. We also demonstrate that the device simulated in this work has same operation at any temperature below T=150$^{\circ}C$ through mixed mode simulation.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1263-1268
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• 2008

In this paper, the low noise power amplifier for GaAs FET ATF-10136 is designed and fabricated with active bias circuit and self bias circuit. To supply most suitable voltage and current, active bias circuit is designed. Active biasing offers the advantage that variations in the pinch-off voltage($V_p$) and saturated drain current($I_{DSS}$) will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets a gate-source voltage($V_{gs}$) for the desired drain voltage and drain current. Using resistive decoupling circuits, a signal at low frequency is dissipated by a resistor. This design method increases the stability of the LNA, suitable for input stage matching and gate source bias. The LNA is fabricated on FR-4 substrate with active and self bias circuit, and integrated in aluminum housing. As a results, the characteristics of the active and self bias circuit LNA implemented more than 13 dB and 14 dB in gain, lower than 1 dB and 1.1 dB in noise figure, 1.7 and 1.8 input VSWR at normalized frequency $1.4{\sim}1.6$, respectively.