• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1700-1705
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• 2013

A second harmonic millimeter wave oscillator utilizing sub-harmonic injection-synchronization is presented. A 8.7GHz oscillator with MES-FET is designed, and is driven as a harmonic output oscillator at 17.4GHz by means of sub-harmonic injection-synchronization. The oscillator operates as a multiplier as well as a oscillator in this scheme. Adopting this method, a high sable, high frequency millimeter wave source is obtainable even though self-oscillating frequency of an oscillator is relatively low. The range of injection-synchronization is about 26MHz, and is proportional to the input sub-harmonic power. The spectrum analysis of the 2nd harmonic output frequency shows remarkably decreased the phase noise level.

• Journal of electromagnetic engineering and science
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• v.8 no.3
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• pp.134-137
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• 2008

This paper proposes a novel quadrature VCO(QVCO) based on direct back-gate second harmonic coupling. The QVCO directly couples the current sources of the conventional LC VCOs through the back-gate instead of front-gate to generate quadrature signals. By the second harmonic injection locking, the two LC VCOs can generate quadrature signals without using on-chip transformer, or stability problem that is inherent in the direct front-gate second harmonic coupling. The proposed QVCO is implemented in $0.18{\mu}m$ CMOS technology operating at 2 GHz with 5.0 mA core current consumption from 1.8 V power supply. The measured phase noise of the proposed QVCO is - 63 dBc/Hz at 10 kHz offset, -95 dBc/Hz at 100 kHz offset, and -116 dBc/Hz at 1 MHz offset from the 2 GHz output frequency, respectively. The calculated figure of merit(FOM) is about -174 dBc/Hz at 1 MHz offset. The measured image band rejection is 46 dB which corresponds to the phase error of $0.6^{\circ}$.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1513-1522
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• 2018

This paper proposes a new islanding detection method for inverter-based distributed generators by continuously injecting a negligible amount of 2nd order harmonic current. The proposed method adopts a proportional resonant (PR) controller for the output current control of the inverter, and a PR filter to extract the 2nd order harmonic voltage at the point of common coupling (PCC). The islanding state can be detected by measuring the magnitude ratio of the 2nd order harmonic voltage to the fundamental voltage at the PCC by injecting a 2nd order harmonic current with a 0.8% magnitude. The proposed method provides accurate and fast detection under grid voltage unbalance and load unbalance. The operation of the proposed method has been verified through simulations and experiments with a 5kW hardware set-up, considering the islanding test circuit suggested in UL1741.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1561-1563
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• 2008

We report an optical second harmonic generation measurement that allows direct probing of dynamical carrier motion in organic field effect transistors. Carrier injection and transport process are discriminated. The mobility and contact resistance of pentacene FETs are determined from the visualized diffusion-like carrier motion.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.682-690
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• 2012

In this paper, a highly linear self oscillating mixers(SOM) using second harmonic injections are presented. The H-slot defected ground structure(DGS) is designed as a balanced resonator for oscillation in the proposed SOM. Since the H-slot DGS resonator achieves a high Q factor, it is a suitable structure to provide low phase noise for the oscillator. The single balanced mixer is utilized in this work and it provides good LO-RF isolation since balanced LO signals are suppressed at the RF input port. In order to inject the second harmonic of the IF, we propose two different methods using feedback loops. In the first method, IF achieves a 3.08 dB conversion gain at 226 MHz with input power of -20 dBm at 5 GHz RF input signal. The IF achieves 2 dB conversion gain at 423 MHz with the input power of -20 dBm at 5.2 GHz RF input signal in the second method. The measured IMD3s are 61.8 dB and 65 dB for the each method. These SOMs present improved linearity compared to that without the second harmonic injection because IMD3s are improved by 18. dB and 21 dB for each method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.152-158
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• 2004

A low phase noise frequency synthesizer at X-Band which employs the subharmonic injection locking was designed and tested. The designed frequency synthesizer consists of a 1.75 GHz master oscillator - which also operates as a harmonic generator - and a 10.5 GHz slave oscillator. A 1.75 GHz master oscillator based on PLL technique used two transistors - one constitutes the active part of VCO and the other operates as a buffer amplifier as well as harmonic generator. The first stage operates a fixed locked oscillator and using the BJT transistor whose cutoff frequency is 45 GHz, the second stage is designed, operating as a harmonic generator. The 6th harmonic which is produced from the harmonic generator is injected into the following slave oscillator which also behaves as an amplifier having about 45 dB gain. The realized frequency synthesizer has a 7.4 V/49 mA, -0.5 V/4 mA of the low DC power consumption, 4.53 dBm of output power, and a phase noise of -95.09 dBc/Hz and -108.90 dBc/Hz at the 10 kHz and 100 kHz offset frequency, respectively.

• Transactions on Electrical and Electronic Materials
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• v.9 no.4
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• pp.151-155
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• 2008

Using pentacene field effect transistors (FETs) with Au source and drain electrodes, electron injection from the Au electrodes into the pentacene was investigated. The capacitance-voltage (C-V) and optical second harmonic generation (SHG) measurements were employed. Electron injection from the Au electrodes was suggested by the hysteresis behavior with the C-V characteristics and slowly decaying SHG signal under DC biasing, A mechanism of hole-injection assisted by trapped electrons is proposed. To confirm electron injection process, light-emitting behavior under the application of AC applied voltage was observed.

• Journal of IKEEE
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• v.26 no.1
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• pp.95-103
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• 2022

In this paper, the efficiency of a sensorless method with square-wave injection for a low-cost inverter, so called B4 inverter is presented. This inverter comprises only 4 switches to reduce system cost. It is distinguished from the conventional B6 inverter that has 6 of switching elements. The B4 inverter, injected a 1 kHz of harmonic wave, has been modelled using the functions and library in Matlab/Simulink. This paper described each component of sensorless algorithm. Among them, the Notch Filter is used to extract the harmonic component of the phase current and a second-order low-pass filter was used to reduce the ripple of the estimated speed. It is shown through simulation that the rotor angle of a permanent magnet synchronous motor is detected by multiplying the current waveform extracted using the notch filter by the harmonic voltage. The feasibility of the proposed method is shown through Simulink simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.4
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• pp.312-319
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• 2014

When distributed generation such as a wind power system is connected to the grid, it should meet grid requirements like IEEE Std. 1547, which regulates the anti-islanding method. Since the islanding may cause damage on electrical equipments or safety hazards for utility line worker, a distributed generation should detect it as soon as possible. This paper proposes a hybrid anti-islanding method coupled with the active and passive detection methods. To enhance the harmonic extraction capability for an active harmonic injection method, cascaded second-order band-pass filter and signal processing scheme are employed. Simulation and experiments are carried out under the islanding test condition specified in IEEE Std. 1547. Passive over/under voltage and over/under frequency methods are combined with the active method to improve the detection speed under certain condition. The simulation and experimental results are presented to verify that the proposed hybrid anti-islanding method can effectively detect the islanding.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.70-71
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• 2007

Analyzing pentacene field effect transistors (FETs) with Au source and drain electrodes as Maxwell-Wagner effect elements, electron and hole injection from the Au electrodes into the FET channel were examined using current-voltage (I-V), capacitance-voltage (C-V) and optical second harmonic generation (SHG) measurements. Based on these results, a mechanism of the hole and electron injection into pentacene from the Au electrodes and subsequently recombination mechanism with light-emitting in the pentacene layer are discussed, with taking into account the presence of trapped charges.