• The Journal of the Korea Contents Association
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• v.6 no.4
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• pp.1-10
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• 2006

In this paper, a broadband RF module is designed and tested for 2.4GHz band applications. The RF module is composed of a low noise amplifier (LNA) with a three stage amplifier, a single ended gate mixer, matching circuits, a hairpin line band pass filter and a Chebyshev low pass filter to convert the radio frequency (RF) into the intermediate frequency (IF). The LNA has a high gain and stability, and the single ended gate mixer has a high conversion gain and wide dynamic range. In the analysis of the broadband RF module, the composite harmonic balance technique is used to analyze the operating characteristics of an RF module circuit. The RF module has a 55.2dB conversion gain with a 1.54dB low noise figure, $-120{\sim}-60dBm$ wide RF power dynamic range, -60dBm low harmonic spectrum and a good isolation factor among the RF, IF, and local oscillator (LO) ports.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.6
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• pp.637-645
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• 2014

This paper presents a new $4{\times}4$ multi-port amplifier(MPA) structure using reconfigurable switching matrices as input and output hybrid matrices(IHM, OHM), and phase/amplitude error calibration circuits. According to the mode selection of the switches, output power can be flexibly and effectively managed since the number of PA's to be used and the number of output port to distribute/combine amplified signals can be controlled. In addition, the proposed structure contains the phase and amplitude error calibration block that helps produce identical amplitudes and desired phase differences to the $4{\times}4$ OHM, resulting in optimizing the port-to-port isolation of the MPA system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2484-2490
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• 2012

This study reports on the development and performance verification of cell simulation boards of simulator and the embedded program for board control of the battery management system (BMS) of electric vehicle (EV) cars, which manages the next-generation automotive lithium-ion battery pack. Here, we have improved the speed of the simulator by using operational (OP) amplifier and transistors that were connected in series. In addition, using a digital analog converter (DAC) in each channel, we have improved the performance by channel-to-channel isolation (isolation) as compared to the traditional methods. Furthermore, by constructing a current-limiting protection circuit, one can be protected from disturbance and, by utilizing a precision shunt resistor for the current sensor, we have increased the precision of the current control. In order to verify the performance of the developed simulator, we have performed the experiment 10 times, with values ranging from 0.5 V to 5 V, and a voltage drop step of 0.5 V. Significance analysis of experimental data, and repeatability tests were performed, showing an average standard deviation of 0.001~0.004 V, indicating high repeatability and high statistical significance of the current method and system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.359-365
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• 2002

In this work, a new type of the active array antenna for IMT-2000 base stations by using dual-polarization diversity is proposed and developed. As an element of array antenna, a single micorstrip patch antenna of ${\pm}$ 45$^{\circ}$slanted is designed by obtaining the bandwidth of 1,885 ㎒ to 22,000 ㎒. The polarization isolation between two linearly polarized waves is less than 16 ㏈. The gain of element antenna is more than 7 ㏈i. finally, 2${\times}$8 dual-polarization active array antenna is developed with ElRP of 1,200 W and polarization isolation of 20 ㏈ by placing a low power amplifier at each antenna element.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12B
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• pp.1747-1753
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• 2001

This paper describe the design and fabrication of a SMD type Wilkinson power divider for PCS basestation. It has been designed for commercial power amplifier system by HP-ADS and fabricated with the size 0.56 $\times$ 0.35 inches. As a result, the power divider was well-operated in the frequency ranges of 1.75 ∼ 1.98GHz for the application of PCS system. The power divider reveals insertion loss 0.2dB, isolation -19.8dB, amplitude balance 0.02dB, phase balance 0.5o, input and output impedance matching -20.6dB respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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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 Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.521-524
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• 2009

Response to nerve stimulation platform for implementing measures to detect finger movement has been functioning as an important factor. This stimulated finger on the nerve and muscle responses would vary. In other words, the finger movement of the muscle response to nerve stimulation and sensing Actuator for the H/W development is needed. In addition, a low power embedded CPU based on the top was used. H/W configuration portion of the isolation power, constant current control, High impedance INA, amplifier parts, and the stimulus mode and the Micro-control the status of current, AD converter Low Data obtained through the processing system is implemented.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.50-54
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• 2015

In this paper, we report on a high performance 94 GHz MMIC mixer module using 0.1-um metamorphic high electron mobility transistors (MHEMTs). A modified resistive mixer with a RF amplifier was proposed in this work for low conversion loss and high LO-RF isolation. The MMIC mixer module was fabricated using a MMIC chip and CPW-waveguide transitions. The fabricated mixer chip and module showed a low conversion loss of 6.3 dB and 9.5 dB, and LO-RF isolations of 24.8 and 30.4 dB at 94 GHz, respectively. This results are superior to those of previously W-band (75-110 GHz) MMIC mixers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2286-2292
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• 2011

In this paper we present the design of Low Noise Amplifier(LNA), mixer and filter for RF front-end part of partial discharge monitoring system. The monitoring system of partial discharge in high voltage power machinery is used to prevent many kinds of industrial accidents, and is usually composed of three parts - sensor, RF front-end and digital microcontroller unit. In our study, LNA, mixer and filter are key components of the RF front-end. The LNA consists of common gate and common source-cascaded structure and uses the resistive feedback for broad band matching. A coupled line structure is utilized to implement the filter, of which size is reduced by the meander structure. The mixer is designed using dual gate structure for high isolation between RF and local oscillator signal.

• ETRI Journal
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• v.30 no.2
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• pp.249-254
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• 2008

In this paper, we demonstrate an electrically band-limited carrier-suppressed return-to-zero (EB-CSRZ) signal generator operating up to a 10 Gbps data rate comprising a single-stage Mach-Zehnder modulator and a wideband signal mixer. The wideband signal mixer comprises inverter stages, a mixing stage, and a gain amplifier. It is implemented by using a 0.13 ${\mu}m$ CMOS technology. Its transmission response shows a frequency range from DC to 6.4 GHz, and the isolation response between data and clock signals is about 21 dB at 6.4 GHz. Experimental results show optical spectral narrowing due to incorporating an electrical band-limiting filter and some waveform distortion due to bandwidth limitation by the filter. At 10 Gbps transmission, the chromatic dispersion tolerance of the EB-CSRZ signal is better than that of NRZ-modulated signal in single-mode fiber.