• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.774-777
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• 2005

In this paper, a constant frequency phase shifting PWM controlled voltage source full bridge-type series load resonant high-frequency inverter using the IGBT power modules is presented for innovative consumer electromagnetic induction heating applications such as a hot water producer, steamer and super heated steamer. The full bridge arm side link passive quasi-resonant capacitor snubbers in parallel with the each power semiconductor device and high frequency AC load side linked active edge inductive snubber-assisted series load resonant tank soft switching inverter with a constant frequency phase shifted PWM control scheme is discussed and evaluated on the basis of the simulation and experimental results. It is proved from a practical point of view that the series load resonant and edge resonant hybrid high-frequency soft switching PWM inverter topology, what is called class DE type. including the variable-power variable-frequency(VPVF) regulation function can expand zero voltage soft switching commutation range even under low output power setting ranges, which is more suitable and acceptable for induction heated dual packs fluid heater developed newly for consumer power utilizations. Furthermore, even in the lower output power regulation mode of this high-frequency load resonant tank high frequency inverter circuit it is verified that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.7 s.361
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• pp.54-61
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• 2007

A variable gain low noise amplifier (VG-LNA) implemented in TSMC 0.18 um process is presented. This VG-LNA is designed of two stage amplifier, and its gain is controlled by the shunt feedback loop composed of a gain control transistor (GCT) and a coupling capacitor in second stage. The channel resistance of GCT in the shunt feedback loop influences the input and output stages of a second stage by the Miller effect. Total gain of the proposed VG-LNA is changed by two factors, the load impedance reduction and the interstage mismatch by controlling the channel resistance of the GCT. Consequently, by adding a shunt feedback with a gain control transistor, this proposed VG-LNA achieves both wide gain tuning range of 37 dB and continuous gain control simultaneously.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.490-492
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• 2010

A swing level controlled voltage-mode transmitter is proposed to support a stub series-terminated logic channel with center-tapped termination. This transmitter provides a swing level control to support the diagnostic mode and improve the signal integrity in the absence of the destination termination. By using the variable parallel termination, the proposed transmitter maintains the constant output impedance of the source termination while the swing level is controlled. Also, the series termination using an external resistor is used to reduce the impedance mismatch effect due to the parasitic components of the capacitor and inductor. To verify the proposed transmitter, the voltage-mode driver, which provides eight swing levels with the constant output impedance of about $50{\Omega}$, was implemented using a 70nm 1-poly 3-metal DRAM process with a 1.5V supply. The jitter reduction of 54% was measured with the swing level controlled voltage-mode driver in the absence of the destination termination at 1.6-Gb/s.

• Journal of Power Electronics
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• v.14 no.2
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• pp.292-301
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• 2014

This paper presents a new configuration for a three-phase multilevel voltage source inverter. The main bridge is built from a classical three-phase two-level inverter and three bidirectional switches. A variable DC-link employing two unequal DC voltage supplies and four switches is connected to the main circuit in such a way that the proposed inverter produces four levels in the output voltage waveform. In order to obtain the desired switching gate signals, the fundamental frequency staircase modulation technique is successfully implemented. Furthermore, the proposed structure is extended and compared with other types of multilevel inverter topologies. The comparison shows that the proposed inverter requires a smaller number of power components. For a given number of voltage steps N, the proposed inverter requires N/2 DC voltage supplies and N+12 switches connected with N+7 gate driver circuits, while diode clamped or flying capacitor inverters require N-1 DC voltage supplies and 6(N-1) switches connected with 6(N-1) gate driver circuits. A prototype of the introduced configuration has been manufactured and the obtained simulation and experimental results ensure the feasibility of the proposed topology and the validity of the implemented modulation technique.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.15-17
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• 2005

In this study, tunable dielectric materials are important for resonator, variable capacitor, phased array antenna and other devices application. In this paper, Dielectric constant increased and tuning range increased with the increased of $BaSrTiO_3/Li_{2}CO_{3}$ content, which probably can be explained by the substitution of Ba3+, Li1+ on BaTiO3 lattice. The tunability and dielectric loss of the $BaSrTiO_2/Li_{2}CO_{3}$ thick film, sintered at $1150^{\circ}C$, were about 43 % and 0.234 at 10$\sim$15 MHz, respectively. In case of BaSrTi/MgO, Dielectric constant decreased and tenability increased with the added of $BaSrTiO_3/MgO$. The ferroelectrics properties were distinct when adding Li to BST ceramic thick film, and paraelectrics pattern was distinct when adding Mg.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.55-58
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• 2001

In this paper, we present the results of the design and fabrication of the VCO(Voltage controlled Oscillator) using RF circuit simulator GENESYS and electromagnetic field simulator EMpower Frequency range is fabricated VCO is 850 MHz ~ 950 MHz, which is used Colpitts Circuit. the fabricated VCO is consisted of resonator, oscillator and MSL(Microstrip Line) is used in LC tuning circuit.(operated by negative feedback) MSL(Microstrip Line), Varactor(Plastic package), low noise TR(SOT-23), chip inductor(1608), chip capacitor(1005), chip resistance(1005). 1005 type is used for sample fabrication of VCO. In the fabrication process, circuit pattern is screen printed on the alumina substrates of over 99.9% purity. Center frequency of the sample VCO is 850MHz at $V_T=1.5V$, while the simulated value was 1.0GHz at $V_T=1.5V$. Variable frequency range of the sample is 860~950MHz in contrast to the 1068~1100MHz of the simulated values.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.153-156
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• 2001

In this paper, we present the results of the design and fabrication of the VCO(Voltage controlled Oscillator) using RF circuit simulator GENESYS and electromagnetic field simulator EMpower Frequency range is fabricated VCO is 850 MHz ~ 950 MHz, which is used Colpitts Circuit. the fabricated VCO is consisted of resonator, oscillator and MSL(Microstrip Line) is used in LC tuning circuit.(operated by negative feedback) MSL(Microstrip Line), Varactor(Plastic package), low noise TR(SOT-23), chip inductor(1608), chip capacitor(1005), chip resistance(1005). 1005 type is used for sample fabrication of VCO. In the fabrication process, circuit pattern is screen printed on the alumina substrates of over 99.9% purity. Center frequency of the sample VCO is 850MHz at $V_T$=1.5V, while the simulated value was 1.0GHz at $V_T$=1.5V. Variable frequency range of the sample is 860~950MHz in contrast to the 1068~1100MHz of the simulated values.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.202-207
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• 1997

Design and fabrication issues for an L-band GaAs Monolithic Microwave Integrated Circuit(MMIC) Voltage Controlled Oscillator(VCO) as a component of Personal Communications Systems(PCS) Radio Frequency(RF) transceiver are discussed. An ion-implanted GaAs MESFET tailored toward low current and low noise with 0.5mm gate length and 300mm gate width has been used as an active device, while an FET with the drain shorted to the source has been used as the voltage variable capacitor. The principal design was based on a self-biased FET with capacitive feedback. A tuning range of 140MHz and 58MHz has been obtained by 3V change for a 600mm and a 300mm devices, respectively. The oscillator output power was 6.5dBm wth 14mA DC current supply at 3.6V. The phase noise without any buffer or PLL was 93dB/1Hz at 100KHz offset. Harmonic balance analysis was used for the non-linear simulation after a linear simulation. All layout induced parasitics were incorporated into the simulation with EEFET2 non-linear FET model. The fabricated circuits were measured using a coplanar-type probe for bare chips and test jigs with ceramic packages.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1059-1065
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• 2017

In this paper, the energy harvester with a piezoelectric materials is modeled as the electric equivalent circuit, and performances of a standard DC method and a Parallel-SSHI method are verified through experiment under variable force and load conditions. Piezoelectric generator consists of mass, damper and spring constant, and it is modeled by electrical equivalent circuit with RLC components. Standard DC and Parallel-SSHI are used as power conversion methods, and standard DC consists of full-bridge rectifier and smoothing capacitor. Parallel-SSHI method is composed of L-C resonant circuit, zero-crossing detector and full-bridge rectifier. In case of simulation under $100k{\Omega}$ load condition, the harvested power is $500{\mu}W$ in Standard DC and $670{\mu}W$ in Parallel-SSHI, respectively. In experiment, the harvested power under $100k{\Omega}$ load condition is $420{\mu}W$ in standard DC and $602{\mu}W$ in Parallel-SSHI. Harvested power of Parallel-SSHI is improved by approximately 40% more than that of standard DC method.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2013-2015
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• 2005

In this paper, Effect of $BaSrTiO_3/Li_2CO_3$ on low temperature sintering and dielectric property of thick films has been investigated for variable capacitor on high frequency. The thick films were fabricated by the tape casting and then the structural and dielectric properties as a function of an addition composition ratio and sintering temperature were studied. For the thick film sintered at $1050^{\circ}C$, it was densified to 96% of $BaSrTiO_3$ theoretical density by the addition of 10 $wt{\cdot}%$ $BaSrTiO_3/Li_2CO_3$. Dielectric constant increased and Curie temperature lowered with the increased of $BaSrTiO_3/Li_2CO_3$ content, which probably can be explained by the substitution of $Ba^{3+},Li^{1+}$ on $RaTiO_3$ lattice. The tunability and dielectric loss of the $BaSrTiO_3/Li_2CO_3$ thick film, sintered at $1350^{\circ}C$, were about 26% and 0.234 at $10{\sim}15MHz$, respectively.