• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.106-111
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• 2015

Since most reference voltage generator circuits have bi-stable characteristics, it is important to employ a proper start-up circuit to operate a reference generator in the desired state. In this paper, we propose a start-up circuit for a low voltage reference generator. This start-up circuit determines the state of the circuit reliably by measuring the current drawn by BJTs in the circuit, which is well-defined in the desired state. To measure the current using CMOS-compatible devices only, a comparator with an internal offset voltage is used. The reliability of the proposed circuit is confirmed by Monte-Carlo simulations of the start-up operation, which show that, with the proposed start-up circuit, the low voltage reference generator starts reliably with supply voltages over 850mV even in the presence of device mismatches.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1544-1551
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• 2007

A start-up circuit of the bandgap reference voltage generator of cascode current mirror type with wide operating voltage range and enhanced power-up characteristics is proposed in the paper. It is confirmed by simulation that the newly proposed start-up circuit does not affect the operation of the bandgap reference voltage generatory even though the supply voltage(VDDA) is higher and has more stable power-up characteristic than the conventional start-up circuit. Test chips are designed and fabricated with $0.18{\mu}m$ tripple well CMOS process and their test has been completed. The mean value of measured the reference voltage(Vref) is 738mV and The three sigma value($3{\sigma}$) is 29.88mV.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.6
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• pp.31-38
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• 2009

To improve the image quality and lower the power consumption of the mobile applications, it is the one of the best candidate to control the backlight unit of the LCD module with ambient light. Ambient light sensor and readout circuit were integrated in LCD panel for the mobile applications, and we designed them with LTPS TFT. We proposed noble start-up correction in order to correct the variation of the photo sensors in each panel. We used time-to-digital method for converting photo current to digital data. To effectively merge time-to-digital method with start-up correction, we proposed noble dual slope correction method. The entire readout circuit was designed and estimated with LTPS TFT process. The readout circuit has very simple and stable structure and timing, so it is suitable for LTPS TFT process. The readout circuit can correct the variation of the photo sensors without an additional equipment, and it outputs the 4-levels digital data per decade for input luminance that has a dynamic range of 60dB. The readout rate is 100 times/sec, and the linearity error for digital conversion is less than 18%.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.152-153
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• 2010

This paper presents the design of a low-input-voltage step-up converter. Such circuits can be useful for single fuel cell to generate less than 0.7V. Important issues to design it are physical volume, efficiency and start-up method. In this paper, we propose a step-up converter with a simple start-up circuit. The operation of proposed circuit is presented and the experimental results are provided to verify the feasibility of the proposed technique.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.247-250
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• 2012

This paper describes a DC-DC Boost converter for Thermoelectric Energy Harvesting. The designed converter boosts the $V_{DD}$ through a start-up block from a low output voltage of thermoelectric devices and the boosted $V_{DD}$ is used to operate the internal block circuits. When $V_{DD}$ reaches a predefined value, a detector circuit makes the start-up block turn off for minimizing current consumption. The final boosted $V_{OUT}$ is achieved by alternately operating the DC-DC converter for $V_{DD}$ and the other converter for final output $V_{OUT}$ according to the comparator output. Simulation results shows that the designed converter outputs 2.8V from an input voltage of 200mV. The area of the chip designed using a 0.35um CMOS process is $1.52mm{\times}0.95mm$ including pads.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.581-584
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• 2014

In this paper, a micro-scale photovoltaic(PV) energy harvesting system is proposed where an MPPT(Maximum Power Point Tracking) control is implemented using an energy distribution technique. Miniature PV cells output very low energy and low voltages, and thus, they cannot be used to directly power the MPPT controller. In the proposed system, a start-up circuit boosts an internal Vcp, and the boosted Vcp is used to operate the internal MPPT control block. When the Vcp reaches a predefined value, a detector circuit makes the start-up block turn off and provide a power converter with the energy from the PV cell. When the Vcp decreases such that the MPPT controller can not be operated, the energy transferred to the power converter is blocked and the start-up circuit is reactivated. In this way, the MPPT function is achieved by alternately operating the start-up circuit and the power converter using the energy distribution technique, and the harvested energy is transferred to a load through a PMU(Power Management Unit). The proposed circuit is designed in a 0.35um CMOS process and its functionality has been verified through extensive simulations. The designed chip area including pads is $1430um{\times}1110um$.

• Journal of IKEEE
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• v.17 no.3
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• pp.284-293
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• 2013

This paper describes a DC-DC boost converter for thermoelectric energy harvesting. The designed converter boosts the VDD through a start-up block from a low-output voltage of a thermoelectric device and the boosted VDD is used to operate the internal control block. When the VDD reaches a predefined value, a detector circuit makes the start-up block turn off to minimize current consumption. The final boosted VOUT is achieved by alternately operating the DC-DC converter for VDD and the main DC-DC converter for VOUT according to the comparator outputs. Simulation results shows that the designed converter generates 2.65V from an input voltage of 200mV and its maximum power efficiency is 63%. The area of the chip designed using a 0.35um CMOS process is $1.3mm{\times}0.7mm$ including pads.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1996.11a
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• pp.49-52
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• 1996

This paper reports the development of an electronic starter for fluorescent lamps, which is so smartly designed that can be used directly in existing installations. The key point of the design lies in the protection of lamp filaments by sufficient preheating and at the same time in the control of time constant for start-up circuit. The starter is consisted of three system parts: a rectifier pact, a switching part. and a gate control part. The characteristics of the developed electronic starter is compared with those of a conventional glow starter. As a result, blackening of lamps is almost reduced due to the stable and idealized start-up characteristics. And, furthermore, it is shown that its slaving time is shortened at about half the level of the conventional one and the starting power is also reduced.

• Journal of Power Electronics
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• v.5 no.3
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• pp.240-246
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• 2005

Considering the start-up and economical efficiency, the optical sensor technique using a slotted-disk and an opto-interrupter are appropriate, however, this method needs three opto-interrupters and a slotted-disk when driving the 6/4 pole SRM(switched reluctance motor). In this paper, we propose an economic method by replacing the conventional opto-interrupter and slotted-disk with only optical sensor which enables the motor to start up and forward and reverse operation. Also the control circuit includes only analog devices, which makes the process more economical.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1304-1306
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• 1996

A regenerative signal amplifying gate driver of self-excited electronic ballast is presented. It can be used for high pressure sodium (HPS) lamp without auxiliary external ignitor. Since the HPS lamp requires very high ignition voltage at start up, the resonant frequency of the circuit must be increased to obtain high voltage oscillations in spite of relatively small resonant current. The presented gate driver amplifies the current of gate drive transformer and raises the gate-source voltage Quickly to turn on the MOSFET switches. Hence, the resonant frequency can be increased more than 100kHz. The HPS lamp used in the simulation and experiment has the rating of 400W input power at 220V input ac voltage source. The experiments show that the resonant frequency is above 150kHz at start up.