• Journal of Advanced Marine Engineering and Technology
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• 제30권8호
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• pp.901-906
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• 2006

In this paper, the power amplifier using active bias circuits for LDMOS(Lateral Diffused Metal Oxide Semiconductor) MRF-21180 is designed and fabricated. According to change the temperature, the gate voltage of LDMOS is controlled by the fabricated active bias circuits which is made of PNP transistor to suppress drain current. The driving amplifier using MRF-21125 and MRF-21060 is made to drive the LDMOS MRF-21180 power amplifier. The variation of current consumption in the fabricated 60 watt power amplifier has an excellent characteristics of less than 0.1 A, whereas a passive biasing circuit dissipates more than 0.5 A. The implemented power amplifier has the gain over 9 dB, the gain flatness of less than $\pm$0.1 dB and input and output return loss of less than -6 dB over the frequency range 2.11 $\sim$ 2.17 GHz. The DC operation point of this power amplifier at temperature variation 0 $^{\circ}C$ to 60 $^{\circ}C$ is fixed by active bias circuit.

• Proceedings of the KIPE Conference
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.663-666
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• 2003

This paper presents a speed controller method based on the disturbance torque observer of high performance brushless DC (BLDC) motor drives. In case of the speed control of robot arms and tracking applications with lower stiffness, we cannot design the speed controller gain to be very large from tile viewpoint of the system stability. Thus, the feedforward compensator using disturbance torque observer was proposed. This method can improve the speed characteristic without increasing the speed controller gain. The enhanced speed control performance can be achieved and the speed response against the disturbance torque can be Improved for high-performance BLDC motor drive systems in which the bandwidth of tile speed controller cannot be made large enough. Consequently, speed control for high-performance BLDC motor drives become improved. The simulation results for BLDC motor drive systems confirm the validity of the proposed method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제11권4호
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• pp.599-609
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• 2000

In this paper, sub-harmonically pumped single balanced resistive mixers are presented . Frequency bandwidth is selected for a Ku-band, which is 11.75-12.25GHz for RF, 5.375∼5.625 GHz for LO, and 1 GHz for IF signals. A rat-race hybrid is designed for the accomplishment of single balanced type. A low pass filter (LPF) with photonic band gap(PBG) structure is used for good conversion loss and unwanted harmonics suppression. Two types of mixers are suggested, which are one with no gate bias for no DC power consumption and the other with the IF amplifier for conversion gain. When a LO signal with the power of 6 dBm at 5.5 GHz is injected, a conversion loss of 12.17dB and a conversion gain of 7.83 dB are obtained for each mixer. For the both mixers , LO to RF isolation of 20 dB and LO to IF isolation of 60dB are obtained. With the RF power of -30dBm to -3dBm, the mixer shows linear characteristics region of IF. this mixer can be applied for Ku-band and other microwave communication systems.

• Proceedings of the KIEE Conference
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• 대한전기학회 1997년도 하계학술대회 논문집 B
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• pp.606-608
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• 1997

In this paper, Neuro-Fuzzy Controller(NFC), a fuzzy system realized using a neural network, is to adopt for the multivariable system. In the multivariable system, the interactive effects between the variables should be taken into account. A simple compensator, using the steady-state information can be obtained for open-loop stable systems, is presented to cope with this problem. However, it should be supposed that the plant is unknown to the control system designer, but an estimate of the DC gain has been obtained by carrying out experiments on the plant. Also, if the variables are not combinated completely, it is difficult to design the controller. Therefore, we design a neuro-fuzzy controller which controls a multivariable system with only input output informations, and compare its performance with that of a PI controller. In the proposed controller, the construction of the membership functions and rule base, which is highly heuristic, can be achieved using a training process. This allows the combination of knowledge of human experts and evidence from input-output data.

• Journal of the Institute of Electronics Engineers of Korea TC
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• 제48권11호
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• pp.89-94
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• 2011

In this paper, we developed the W-band MMIC low noise amplifier for the millimeter-wave seeker using the tuner system. The MHEMT devices for MMIC LNA exhibited DC characteristics with a drain current density of 692mA/mm, an extrinsic transconductance of 726mS/mm. The current gain cutoff frequency(fT) and maximum oscillation frequency($f_{max}$) were 195GHz and 305GHz, respectively. The fabricated W-band low noise amplifier represented S21 gain of 7.42dB at 94 GHz and noise figure of 2.8dB at 94.2 GHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제23권2호
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• pp.103-107
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• 2009

PI controller is widely used as voltage control system of generator. However when a generator system has various characters of continuance, a new PI parameter decision for accurate control is a hard task as method of solving this problem, in this paper, the method to generator voltage control using Neural Network self adaptive control is presented. A property continuous feedback control gain of voltage control system is decided by a rule of delta learning. The function of proposed control method is verified by voltage control experiment results of DC generator.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제65권12호
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• pp.1992-1999
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• 2016

The plasma process is applied to various industrial fields such as high-tech IT industry, textiles and medical. Therefore, there is increasing interest in the plasma power supply, and demand for power devices of high efficiency and high power density is increased. Plasma power supply for process must solve the arc problem, when the plasma is unstable. The output capacitor is closely related to the arc problem. If the output capacitor is smaller, the damage from the arc problem is reduced. However, the small value of the output capacitor affects the operating characteristics of the power supply. In this paper, a LLC resonant converter is adopted, because it can achieve high efficiency and power density in the plasma DC power supply. However, due to the small value of the output capacitor, the converter is operated as a LLCC resonant converter. Therefore, a gain characteristic of LLCC resonant converter is analyzed by using the FHA (First Harmonic Approximation) in plasma power supply. Simulation and experimental results are presented to verify the characteristic analysis of LLCC Resonant Converter.

• Proceedings of the KIEE Conference
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.3124-3126
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• 2000

The application of IR(Infrared) communication is very wide and IR receiver has become a standard of home entertainment. A preamplifier with single 5V supply was designed for IR receiver IC. To operate at long distance, receiver IC should have high gain and low noise characteristic. To provide constant output signal magnitude, independent of transciever distance, gain limiting stage is needed. And to cut-off DC noise component effectively, large resistance and capacitance are required. Transimpedance type preamplifier, and diode limiting amplifier, and current limiting amplifier were designed. It is another function of current limiting amplifier that transforms single input signal to differential output signal. Using AMS BiCMOS model, both BJT version and MOS version was designed. Total power consumption is O.lmW, and IC size is $0.3mm^2$

• Journal of the Institute of Electronics Engineers of Korea SD
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• 제41권11호
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• pp.21-27
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• 2004

In this paper, millimeter-wave monolithic integrated circuit(MIMIC) low noise amplifier(LNA) for V-band, which is applicable to 60 GHz wireless local area network(WLAN), was fabricated using the high performance 0.1 ${\mu}{\textrm}{m}$ $\Gamma$-gate pseudomorphic high electron mobility transistor(PHEMT). The DC characteristics of PHEMT are drain saturation current density(Idss) of 450 mA/mm and maximum transconductance(gm, max) of 363.6 mS/mm. The RF characteristics were obtained the current gain cut-off frequency(fT) of 113 GHz and the maximum oscillation frequency(fmax) of 180 GHz. V-band MIMIC LNA was designed using active and passive device library, which is composed of 0.1 ${\mu}{\textrm}{m}$ $\Gamma$-gate PHEMT and coplanar waveguide(CPW) technology. The designed V-band MIMIC LNA was fabricated using integrated unit processes of active and passive device. The measured results of V-band MIMIC LNA are shown S21 gain of 21.3 dB, S11 of -10.6 dB at 60 GHz and S22 of -29.7 dB at 62.5 GHz. The measured result of V-band MIMIC LNA was shown noise figure (NF) of 4.23 dB at 60 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제25권5호
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• pp.504-514
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• 2014

An MMIC multi-function chip with a low DC power consumption for an X-band active phased array radar system has been designed and fabricated using a 0.5 ${\mu}m$ GaAs p-HEMT commercial process. The multi-function chip provides several functions: 6-bit phase shifting, 6-bit attenuation, transmit/receive switching, and signal amplification. The fabricated multi-function chip with a compact size of $16mm^2(4mm{\times}4mm)$ exhibits a gain of 10 dB and a P1dB of 14 dBm from 7 GHz to 11 GHz with a DC low power consumption of only 0.6 W. The RMS(Root Mean Square) errors for the 64 states of the 6-bit phase shift and attenuation were measured to $3^{\circ}$ and 0.6 dB, respectively over the frequency.