• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.69-78
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• 2007

A Frequency synthesizer for T-DMB and mobile-DTV applications was designed using $0.18{\mu}m$ CMOS process with 1.8V supply. PMOS transistors were chosen for VCO core to reduce phase noise. The VCO range is 920MHz-2100MHz using switchable inductors, capacitors and varactors. Varactor biases that improve varactor acitance characteristics were minimized as two, and $K_{VCO}$(VCO gain) value was aintained by switchable varactor. Additionally, VCO was designed that VCO gain and the interval of VCO gain were maintained using VCO gain compensation logic. VCO, PFD, CP and LF were verified by Cadence Spectre, and divider was simulated using Matlab Simulink, ModelSim and HSPICE. VCO consumes 10mW power, and is 56.3% tuning range. VCO phase noise is -127dBc/Hz at 1MHz offset for 1.58GHz output frequency. Total power consumption of the frequency synthesizer is 18mW, and lock time is about $140{\mu}s$.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1429-1435
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• 2012

DC-DC converter commonly used in photovoltaic systems, fuel cell systems and electric vehicles is a boost converter. The interleaved boost converter, connected in parallel by several boost converters and operated by the phase difference to reduce the input and output current ripple, has been widely used in recent years. Because of small input and output current ripples, the circuit can reduce the size of the input and output capacitors. Thus, instead of conventional electrolytic capacitor, the film capacitor with high reliability can be used and this is the life and reliability of the entire system can be improved. In this paper, the output current ripple formulas of the multi-stage interleaved boost converter are derived, and the characteristics in accordance with duty are found out. In order to verify the abovementioned contents, the derived results will make a comparison with the calculated values by using PSIM tool.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1023-1029
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• 2007

In this paper, we propose the method to solve the BLT equations using Laguerre polynomials in time domain. The solution of BLT equations is obtained by recursive, differential and integral properties of Laguerre polynomials. The verification of the proposed method is tested by applying it to the two-wired transmission line with resistors and capacitors, which is illuminated by the electromagnetic plane wave pulse. And the result is compared with the corresponding transient responses obtained from inverse fast Fourier transform(IFFT) of the frequency domain solutions of BLT equations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.162-172
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• 2011

In this paper, a design and fabrication of 4 W power amplifier for the WiMAX frequency band(2.3~2.7 GHz) are presented. The adopted active device is a commercially available GaN HEMT chip of Triquint Company, which is recently released. The optimum input and output impedances are extracted for power amplifier design using a specially self-designed tuning jig. Using the adopted impedances value, class-F power amplifier was designed based on EM simulation. For integration and matching in the small package module, spiral inductors and interdigital capacitors are used. The fabricated power amplifier with $4.4{\times}4.4\;mm^2$ shows the efficiency above 50 % and harmonic suppression above 40 dBc for second(2nd) and third(3rd) harmonic at the output power of 36 dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.82-90
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• 2013

In this paper, conducted emission from the MDS(Motor Drive System) of a HEV/EV was analyzed using high- frequency circuit modeling in system-level approach. The conducted emission by PWM process can cause RFI(radio- frequency interference) problems in the AM/FM frequency range. In order to mitigate this conducted emission, a high-frequency equivalent circuit model is proposed by analyzing the fundamental circuits, parasitic components in their parts and connections and non-linear characteristics of IGBTs, high-power capacitors, inverters, motors, high-power cables, and bus bars which are composed of the MDS. It is confirmed that the simulated result by the proposed model is well agreed with measured results in spite of a large-scaled analysis in system level. We are looking forward that this approach can be effectively used in the EMC design of HEV/EV.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.11
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• pp.1019-1022
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• 2016

In this paper, a 2~16 GHz GaN wideband power amplifier MMIC s designed and fabricated using the nonuniform power amplifier design technique that utilizes drain shunt capacitors to simultaneously provide each transistor with the optimum load impedance and phase balance between input and output transmission lines. The power amplifier MMIC chip that is fabricated using the $0.25{\mu}m$ GaN HEMT foundry process of Win Semiconductors occupies an area of $3.9mm{\times}3.1mm$ and shows a linear gain of larger than 12 dB and an input return loss of greater than 10 dB. Under a continuous-wave mode, it has a saturated output power of 36.2~38.5 dBm and a power-added efficiency of about 8~16 % in 2 to 16 GHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.136-144
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• 2010

This paper presents the two-switch interleaved active clamp forward converter, which is mainly composed of two active clamp forward converters. Only two switches are required, and each one is the auxiliary switch for the other. So, the circuit complexity and cost are reduced and control is more simple. An additional resonant inductance is employed to achieve ZVS(Zero-Voltage-Switching) during the dead times. Interleaved output inductor currents diminish the voltage and current ripple. Accordingly, the smaller output filter and capacitors lower the converter volume. This research proposed the Two-switch interleaved Active Clamp Forward Converter characteristic. The principle of operation, feature and design considerations is illustrated and the validity of verified through the experiment with a 160[W] based experimental circuit.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1429-1435
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• 2004

In this work, high performance broadband amplifier MMIC including all the matching and biasing components, and electrostatic discharge (ESD) protection circuit was developed for K/Ka band applications. Therefore, external biasing or matching components were not required for the operation of the MMIC. STO (SrTiO3) capacitors were employed to integrate the DC biasing components on the MMIC, and miniaturized LC parallel ESD protection circuit was integrated on MMIC, which increased ESD breakdown voltage from 10 to 300 V. A pre-matching technique and RC parallel circuit were used for the broadband design of the amplifier MMIC. The amplifier MMIC exhibited good RF performances and good stability in a wide frequency range. The chip size of the MMICs was $1.7{\pm}0.8$ mm2.

• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.217-221
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• 2003

In this work, we used a novel RF-CSP to develop a broadband amplifier MMIC, including all the matching and biasing components, for Ku and K band applications. By utilizing an ACF for the RF-CSP, the fabrication process for the packaged amplifier MMIC could be simplified and made cost effective. STO (SrTiO$_3$) capacitors were employed to integrate the DC biasing components on the MMIC. A pre-matching technique was used for the gate input and drain output of the FETs to achieve a broadband design for the amplifier MMIC. The amplifier CSP MMIC exhibited good RF performance (Gain of 12.5$\pm$1.5 dB, return loss less than -6 dB, PldB of 18.5$\pm$1.5 dBm) over a wide frequency range. This work is the first report of a fully integrated CSP amplifier MMIC successfully operating in the Ku/K band.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.117-117
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• 2008

In MIM capacitor, poly-Si bottom electrode is replaced with metal bottom electrode. Noble metals can be used as bottom electrodes of capacitors because they have high work function and remain conductive in highly oxidizing conditions. In addition, they are chemically very stable. Among novel metals, Ru (ruthenium) has been suggested as an alternative bottom electrode due to its excellent electrical performance, including a low leakage of current and compatibility to high dielectric constant materials. Chemical mechanical planarization (CMP) process has been suggested to planarize and isolate the bottom electrode. Even though there is a great need for development of Ru CMP slurry, few studies have been carried out due to noble properties of Ru against chemicals. In the organic chemistry literature, periodate ion ($IO_4^-$) is a well-known oxidant. It has been reported that sodium periodate ($NaIO_4$) can form $RuO_4$ from hydrated ruthenic oxide ($RuO_2{\cdot}nH_2O$). $NaIO_4$ exist as various species in an aqueous solution as a function of pH. Also, the removal mechanism of Ru depends on solution of pH. In this research, the static etch rate, passivation film thickness and wettability were measured as a function of slurry pH. The electrochemical analysis was investigated as a function of pH. To evaluate the effect of pH on polishing behavior, removal rate was investigated as a function of pH by using patterned and unpatterned wafers.