• Journal of Advanced Navigation Technology
• /
• v.16 no.5
• /
• pp.766-772
• /
• 2012

In the present study, wideband microstrip monopole slot antennas which can be applied to the RF4CE Zigbee remote controller are designed. First I-shaped monopole slot antenna which has ${\lambda}g/4$ length at 2.45GHz is designed. In particular, a conducting via is used to connect the microstrip feed line and the ground plane surrounded with the etched slot for the bandwidth improvement. In order to reduce the antenna size, it is changed into L-shaped and T-shaped monopole slot antennas for which improve results of antenna performance are observed. In case of T-shaped monopole slot antenna, impedance bandwidth(VSWR<2) is about 3.32GHz, and also its radiation efficiency and gain is more than 90% and 2.1dBi respectively at whole operating frequency range. In particular, all of proposed monopole slot antennas have the end-fire radiations which has a maximum radiation power toward direction of open ends of monopole slots.

• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1960-1963
• /
• 2002

Transmit diversity schemes we an effective capacity improvement method for down link of wideband code division multiple access (W-CDMA) systems. In this paper, we propose to use transmit antenna subset selection scheme in conjunction with closed loop transmit adaptive array (TxAA). The proposed scheme selects N$\_$s/ optimum antennas among N$\_$${\gamma}$/(>N$\_$s/) transmit antennas in order to maximize diversity gain from selected antennas, and also reduces the cost of RE chains by employing two different types of RF modules fur the selected and the unselected antenna group, respectively. Computer simulation results show performance improvement by the proposed scheme over the conventional TxAA when considering up link control information feedback.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.11
• /
• pp.2391-2396
• /
• 2010

The power-controlled six-port element that can control the local oscillator signal power and receiving RF signal power was designed and implemented in this paper. The direct conversion six-port element configuration was proposed, which provides the constant six-port output power by controlling the six-port input power with various signal strength. The direct conversion six-port element protects the power detector element of six-port receiver from the saturation status and compensates the transmission performance degradation. For implementation of power-controlled six-port element, the power-controlled six-port element including the power controller was analyzed. The implemented power-controlled six-port element shows the power control capability of 36 dB and gain imbalance of about 1.6 dB, phase imbalance of about $4^{\circ}$ in the frequency range of 1.69 GHz. The measured results show the good performance as direct conversion front-end element.

• Journal of the Korea Society of Computer and Information
• /
• v.20 no.2
• /
• pp.79-88
• /
• 2015

This paper introduces surveillance equipment "ADS-B", the core subject of traffic control system and study of ADS-B 1090ES ground receiver. The standard is set not only for functional but also its reliability by analyzing international standard documents and existing products. The Bias circuit is designed for less power consumption, low noise and high gain for RF module. The signal processing is capable of overcoming its bad conditions. MCU part is configured with the latest CPU for high speed communication with external parts and SNMP is selected for remote control communication. The performance of developed receiver satisfies national and international standards and its functions are more advanced compared to foreign receivers.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.3
• /
• pp.678-684
• /
• 2013

This paper describes a low-power baseband circuit for SAW-less LTE-Advanced transmitters. The proposed transmitter baseband circuit consists of a 2nd-order Tow-Thomas type active RC-LPF and a 1st-order passive RC LPF. It can provide a 7 multi-channel cut-off frequencies and wide gain control range of -41 dB ~ 0 dB with a 1-dB step. The proposed 2nd-order active RC-LPF adopts an op-amp in which three other sub-op amps are in parallel connected to reduce DC current for different cutoff frequency. In addition, each sub-op amp adopts both Miller and feed-forward phase compensation method to achieve an UGBW of more than 1-GHz with a small DC power consumption. The proposed baseband circuit is implemented in 65-nm CMOS technology, consuming DC power from 6.3 mW to 24.1 mW from a 1.2V supply voltage for each different cut-off frequency.

• Journal of Sensor Science and Technology
• /
• v.3 no.1
• /
• pp.40-45
• /
• 1994

$112^{\circ}$ rot. x-cut $LiTaO_{3}$ wafer was used as the substrate of SAW gas sensor. Dual delay line SAW device with IDTs which consist of the reference delay line and the sensing delay line was fabricated using photolithigraphy. Each IDTs had 10 finger pairs and finger spacing is 10 microns. One delay line channel is the reference, while the second is the sensing channel with Pb-phthalocyanine film in the propagation path. Pb-phthalocyanine film which is p-type organic semiconductor was evaporated in $10^{-5}$ torr vacuum using shadow mask selectively. Dual delay line oscillator was constructed by using the rf amplifier and AGC. Frequency of the IDTs had the range of $87{\sim}$89 MHz oscillation frequency. Oscillation frequency shifts were investigated as a function of the temperature and the concentration of $NO_{2}$ gas.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.46 no.6
• /
• pp.48-51
• /
• 2009

One-stage low noise amplifier (LNA) using 65 nm RF CMOS technology below 20 GHz is designed to find the optimal bias voltage and optimal width of input transistor so that the maximum figure of merit (FoM) has been achieved. If the frequency is higher than 13 GHz, the amplifier needs two-stage to achieve the higher gain. If the frequency is lower than 5 GHz, one additional capacitor between gate and source should be added to control the power under the limitation. This paper summarizes one-stage LNA overall performances below 20 GHz and this approach can also be applied to other CMOS technology of LNA designs.

• Journal of IKEEE
• /
• v.2 no.1 s.2
• /
• pp.1-14
• /
• 1998

In this paper, Antenna, LNA, Mixer, VCO, and Modulation/Demodulation in Baseband processor which are the RF main components in Wireless LAN system for ultra high-speed communications network are studied. Antenna bandwidth and selective fading due to multipath can be major obstacles in high speed digital communications. To solve this problem, wide band MSA which has loop-structure magnetic antenna characteristics is designed. Distributed mixer using dual-gate GaAs MESFET can achieve over 10dB LO/RF isolation without hybrid, and minimize circuit size. As linear mixing signal is produced, distortions can be decreased at baseband signals. Conversion gain is achieved by mixing and amplification simultaneously. Mixer is designed to have wide band characteristics using distributed amplifier. In VCO design, Oscillator design method by large signal analysis is used to produce stable signal. Modulation/Demodulation system in baseband processor, DS/SS technique which is robust against noise and interference is used to eliminate the effect of multipath propagation. DQPSK modulation technique with M-sequences for wideband PN spreading signals is adopted because of BER characteristic and high speed digital signal transmission.

• Journal of Advanced Navigation Technology
• /
• v.25 no.1
• /
• pp.68-77
• /
• 2021

In this paper, a GPS/MEMS IMU integrated navigation receiver module capable of operating in a high dynamic environment is designed and fabricated, and the results is confirmed. The designed module is composed of RF receiver unit, inertial measurement unit, signal processing unit, correlator, and navigation S/W. The RF receiver performs the functions of low noise amplification, frequency conversion, filtering, and automatic gain control. The inertial measurement unit collects measurement data from a MEMS class IMU applied with a 3-axis gyroscope, accelerometer, and geomagnetic sensor. In addition, it provides an interface to transmit to the navigation S/W. The signal processing unit and the correlator is implemented with FPGA logic to perform filtering and corrrelation value calculation. Navigation S/W is implemented using the internal CPU of the FPGA. The size of the manufactured module is 95.0×85.0×.12.5mm, the weight is 110g, and the navigation accuracy performance within the specification is confirmed in an environment of 1200m/s and acceleration of 10g.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.5
• /
• pp.1120-1128
• /
• 2004

In this paper, we has designed and implemented Up-converter for K-band with high IMD3 performance using balanced power amplifier. It is consisted of PA module and, Local Oscillator module with reject Filter, mixer module and If block, and Up-converter has a local loop path to decide whether it operate or not and has the sensing port to inspect output power level. According to the power budget of designed Up-converter, K-band balanced power amplifier was fabricated by commercial MMIC. Measurement results of up-converter show about 40dB Gain, PldB of 29dBm and OIP3 was 38.25dBm, that is good performance compared to power budgets. We has adjusted gate voltage of MMIC to control more than 30 dB gain. This up-converter was used in transceiver for PTP and PTMP, and applied to digital communication system that use QAM and QPSK modulation.