• Proceedings of the KIEE Conference
• /
• 2006.04b
• /
• pp.351-354
• /
• 2006

Recently, a fuel cell with low voltage and high current output characteristics is remarkable for new generation system It needs both a DC-DC step-up converter and DC-AC inverter to be used in fuel cell generation system Therefor, this paper, consists of an isolated DC -DC converter to boost the fuel cell voltage 380[$V_{DC}$] and a PWM inverter with LC filter to convent the DC voltage to single phase 220[$V_{AC}$]. Expressly, a tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed high frequency isolated ZVZCS PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena Besides the efficiency of 93-97[%]is obtained over the wide output voltage regulation ranges and load variations.

• Journal of electromagnetic engineering and science
• /
• v.4 no.4
• /
• pp.156-161
• /
• 2004

The MMIC cascode VCO is designed, fabricated, and measured for Ku-band Low Noise Blcok(LNB) system using InGaP/GaAs HBT technology. The phase noise of -116.4 dBc/Hz at 1 MHz offset with output power of 1.3 dBm is obtained at 11.526 GHz by applying 3 V and 11 mA, which is comparatively better characteristics than compared with the different configuration VCOs fabricated with other technologies. The simulated results of oscillation frequency and second harmonic suppression agree with the measured results. The phase noise is improved due to the use of the smallest value of inductor in frequency determining network and the InGaP ledge function of the technology. The chip size of $830\time781\;{\mu}m^2$ is also achieved.

• Journal of electromagnetic engineering and science
• /
• v.8 no.3
• /
• pp.129-133
• /
• 2008

An integrated passive device(IPD) technology by semi-insulating(SI)-GaAs-based fabrication has been developed to meet the ever increasing needs of size and cost reduction in wireless applications. This technology includes reliable NiCr thin film resistor, thick plated Cu/Au metal process to reduce resistive loss, high breakdown voltage metal-insulator-metal(MIM) capacitor due to a thinner dielectric thickness, lowest parasitic effect by multi air-bridged metal layers, air-bridges for inductor underpass and capacitor pick-up, and low chip cost by only 6 process layers. This paper presents the Wilkinson power divider with excellent performance for digital cellular system(DCS). The insertion loss of this power divider is - 0.43 dB and the port isolation greater than - 22 dB over the entire band. Return loss in input and output ports are - 23.4 dB and - 25.4 dB, respectively. The Wilkinson power divider based on SI-GaAs substrates is designed within die size of $1.42\;mm^2$.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.5
• /
• pp.235-241
• /
• 2013

A low power CMOS control circuit is applied in an integrated DC-DC buck converter. The integrated converter is composed of a feedback control circuit and power block with 0.35 ${\mu}m$ CMOS process. A current-sensing circuit is integrated with the sense-FET method in the control circuit. In the current-sensing circuit, a current-mirror is used for a voltage follower in order to reduce power consumption with a smaller chip-size. The N-channel MOS acts as a switching device in the current-sensing circuit where the sensing FET is in parallel with the power MOSFET. The amplifier and comparator are designed to obtain a high gain and a fast transient time. The converter offers well-controlled output and accurately sensed inductor current. Simulation work shows that the current-sensing circuit is operated with an accuracy of higher than 90% and the transient time of the error amplifier is controlled within $75{\mu}sec$. The sensing current is in the range of a few hundred ${\mu}A$ at a frequency of 0.6~2 MHz and an input voltage of 3~5 V. The output voltage is obtained as expected with the ripple ratio within 1%.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.1
• /
• pp.20-26
• /
• 2009

In this paper, the switching mode conversion type pulse charger by fly-back converter method for lead battery of the solar cell generator equipment is proposed. And we propose the control circuit and design method of insulated switching mode convert type pulse charger by fly-back convert method in the lead battery. The proposed system can minimize the current consumption by digital pulse. Also the proposed system can generate the constant 10[KHz] frequency, transmit the signal with main control system in the power control system. And it supervises the state of lead battery using one chip micro processor. The proposed the switching mode conversion type pulse charger by the fly-back converter method can charge fast and stabilize lead battery with nominal value 12[V], 20[AH]. Also we propose the design procedure of the power control circuit for turn ratio of fly-back inductor and determining method of values such as the charging current, bulk current, partial current, over current value and fixed charging voltage. The experiment results for the voltage and current wave for partial, bulk, over and fixed charging period show the good charging effect and performance. And the PCB and internal coupling diagram of the switching mode conversion type pulse charger by fly-back converter method is presented.

• Journal of Korea Society of Industrial Information Systems
• /
• v.22 no.2
• /
• pp.71-78
• /
• 2017

In This Paper, A DC-DC Boost Converter for Portable Device has been Proposed. The Converter Which is Operated with 1 MHz High Switching Frequency is Capable of Reducing Mounting Area of Passive Devices Such as Inductor and Capacitor, Consequently is Suitable for Portable Device. This Boost Converter Consists of a Power Stage and a Control Block and a Protect Block. Proposed DC-DC Boost Converter has been Designed a 0.18 um Magnachip CMOS Process Technology, we Examined Performances of the Fabricated Chip and Compared its Measured Results with SPICE Simulation Data. Simulation Results Show that the Output Voltage is 4.8 V in 3.3 V Input Voltage, Output Current 95 mA Which is Larger than 20~50 mA.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.387-390
• /
• 1998

In this paper, HBT's with lower phase noise and passive elements, such as resistors, capacitors and inductors, for resonance and impedance matching networks are designed, fabricated, tested, and carefully analysed, respectively, and then, they are integrated for the design and fabrication of functional X-band oscillators with lower phase noise. Epi-wafers for HBT's with the structure of graded $Al_{x}$G $a_{1-x}$ As emitter and C-doped base layer of 700.angs. thick were used to specially emphasize the improvement of $f_{T}$ and $f_{max}$, and the lowering of phase noise, in design aspects. At the test frequencies of 12GHz, capacitances of MIM capacitors, spiral inductor, and resistances are 0.5~10pF, 0.4~11.06nH, and 20~1,380.ohm., respectively. The emitter size of HBY's for the X-band MMIC oscillators is 3*10u $m^{2}$, and find chip size is 0.9*0.9m $m^{2}$..EX>.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.7 no.1
• /
• pp.28-35
• /
• 2007

This paper presents a high-speed flash analog-to-digital converter (ADC) for ultra wide band (UWB) receivers. In this flash ADC, the interpolating technique is adopted to reduce the number of the amplifiers and a linear and wide-bandwidth interpolating amplifier is presented. For this ADC, the transistor size for the cascaded stages is inversely scaled to improve the trade-off in bandwidth and power consumption. The active inductor peaking technique is also employed in the pre-amplifiers of comparators and the track-and-hold circuit to enhance the bandwidth. Furthermore, a digital-to-analog converter (DAC) is embedded for the sake of measurements. This chip has been fabricated in $0.13{\mu}m$ 1P8M CMOS process and the total power consumption is 113mW with 1V supply voltage. The ADC achieves 4-bit effective number of bits (ENOB) for input signal of 200MHz at 5-GSample/sec.

• Journal of the Institute of Convergence Signal Processing
• /
• v.9 no.2
• /
• pp.135-140
• /
• 2008

In this paper, the spiral antenna with the center frequencies of 315MHz, 433MHz, and 447MHz for RKE system of a vehicle is designed on PCB. The antenna is microstrip line-fed, and applied PIFA concept near the feeding part to easily tune center frequency and input impedance. The PIFA-type spiral antenna with the size of $30mm{\times}20mm$ is designed on printed PCB by considering the effect of circuits and components on PCB, ECU case and vehicle body. Also chip inductor inserted dual-band spiral antenna of 315MHz and 447MHz is designed. We found that the antenna designed on PCB satisfied the antenna specifications through measurement and field test.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.05a
• /
• pp.347-352
• /
• 2004

The author present a modified multi-loop algorithm including feedforward for controlling a 55kW step down chopper in the power supply of Maglev. The control law for the duty cycle consists of three terms. The first is the feedforward term which compensates for variations in the input voltage. The second term consists of the difference between the slowly moving inductor current and output current. The third term consists of proportional and integral terms involving the perturbation in the output voltage. This perturvation is derived by subtracting the desired output voltage from the actual output voltage. The proportional and integral action stabilizes the system and minimizes output voltage error. In order to verify the validity of the proposed multi-loop controller, simulation study was tried using Matlab simulink.