• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.3
• /
• pp.339-345
• /
• 2001

In this paper, FG-CPW (Finite-Ground Coplanar Wave-Guide) balanced diode mixer is presented. Frequency bandwidth is selected for a C-band, which is 5.72~5.82 GHz for RF, 5.58~5.68 GHz for LO, and 140 MHz for IF signals. A rat-race hybrid is designed for the accomplishment of single balanced type. A low pass filter (LPF) with CPW structure is used far good conversion loss and unwanted harmonics suppression. When LO signal with the power of 4 dBm at 5.635 GHz is injected, a conversion loss of 6.2 dB is obtained for the mixer. Also, the LO to RF and LO to IF isolation of 30 dB and 40 dB are obtained, respectively. This mixer can be used in the area on wireless LAN application.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.4
• /
• pp.753-758
• /
• 2009

This paper is proposed the hardware structure and signal processing method of the RF-Tag based on heart sound to develop the mobile biomedical information device for the u-healthcare system. The RF-Tag in this study is consisted of a skin temperature sensor, a dynamic microphone for heart sound detection, Bluetooth communication to transmute healthcare data, and pulse period detection algorithm with adaptive gain controller. We experimented to evaluate performance of the RF-Tag in noisy environments. In addition, the RF-Tag has shown the good performance in the results of experiment. If the proposed methods in this study apply to design the u-healthcare device, we will be able to get the exact health data on real time in mobile environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.7
• /
• pp.669-674
• /
• 2011

In this paper, a method for reduction of spurious signal in Digital RF Memory(DRFM) is proposed. Spurious response is a major performance issue of DRFM. This method is based on mixing a random phase LO signal into input IF signal and sampling it. The random phase LO signal is generated by high speed phase shifting characteristic of Direct Digital Synthesizer(DDS). Through this technique, we achieved an enhancement of 5~10 dB of spurious response.

• Journal of Positioning, Navigation, and Timing
• /
• v.11 no.2
• /
• pp.127-134
• /
• 2022

In this paper, a low-cost, flexible GPS simulator based on USRP is designed as a general-purpose software wireless front-end. The simulator consists of a software GPS signal generator and a USRP-based RF transmitter. The simulator supports various scenarios including specified reception time, quantization bit level, I/Q data types, IF frequency, sampling frequency, SNR, ionospheric delay and user dynamics. The generated GPS RF signal is verified using the spectrum analyzer and off-the-shelf GNSS receivers such as U-blox M8T. The experimental results shows that the difference between generated and real live signal is ignorable. It is expected that designed GPS simulator can be used to GNSS signal design, receiver design and signal processing algorithms such as anti-jamming.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.2
• /
• pp.169-179
• /
• 1999

In this paper, a GaAs MESFET single-ended resistive mixer with high linearity and isolation is designed. The bias voltage of this mixer is applied only gate of GaAs MESFET to use the channel resistance. The LO is applied the gate and the RF is applied the drain through 7-pole hairpin bandpass filter to obtain the proper isolation thru LO-RF. The IF is extracted from the source with short circuit and lowpass filter. Using extracted equivalent circuits for LO and RF, conversion loss is calculated and compared with result of harmonic balance analysis. Measured conversion loss of this S-band down converter mixer is 8.2~10.5dB by considering the measured 3.0~3.4dB RF 7-pole hairpin bandpass filter loss and IP3in is 26.5dBm at Vg=-0.85~-1.0V in distortion performance.

• Journal of electromagnetic engineering and science
• /
• v.9 no.2
• /
• pp.98-104
• /
• 2009

An InGaP/GaAs MMIC LC VCO designed with Harmonic Noise Frequency Filtering(HNFF) technique is presented. In this VCO, internal inductance is found to lower the phase noise, based on an analytic understanding of phase noise. This VCO directly drives the on-chip double balanced mixer to convert RF carrier to IF frequency through local oscillator. Furthermore, final power performance is improved by output amplifier. This paper presents the design for a 1.721 GHz enhanced LC VCO, high power double balance mixer, and output amplifier that have been designed to optimize low phase noise and high output power. The presented asymmetric inductance tank(AIT) VCO exhibited a phase noise of -133.96 dBc/Hz at 1 MHz offset and a tuning range from 1.46 GHz to 1.721 GHz. In measurement, on-chip down-converter shows a third-order input intercept point(IIP3) of 12.55 dBm, a third-order output intercept point(OIP3) of 21.45 dBm, an RF return loss of -31 dB, and an IF return loss of -26 dB. The RF-IF isolation is -57 dB. Also, a conversion gain is 8.9 dB through output amplifier. The total on-chip down-converter is implanted in 2.56${\times}$1.07 mm$^2$ of chip area.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.1 no.1
• /
• pp.8-19
• /
• 2006

The RF Module which can be adjusted for a digital terrestrial and multi standard(DVB-C, ISDB-T, DVB-H) reception is developed. The Module by single conversion does divide a broadband(45MHz~860MHz) broadcasting channels into three-bands(UHF, VHF_HIGH, VHF_LOW) to satisfy some electrical performances such as image signal rejection, phase noise, IF flatness etc and digital reception specifications such as analog and digital adjacent channel protection, co-channel protection which is important in environment with co-existence both analog and digital broadcasting systems.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.13 no.4
• /
• pp.277-284
• /
• 1988

A 12GHz low-noise amplifier, a single gate GaAs MESFET mixer, and a low-pass filter have been fabricated for DBS receiver applications by using MIC technology. Each subsystem contains DC block with symmetric line and ship capacitor, respectively. The frequency converter with chip capacitor exhibits a 20-23 dB conversin gain with a RF bandwidth of 11.581-11.981 GHz and an IF bandwidth of 581-981MHz. Rf bandwidth of 12.1GHz and an IF banewidth of 1GHz.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.3A
• /
• pp.345-355
• /
• 2006

The RF Module which can be adjusted for a digital terrestrial and multi standard(DVB-C, ISDB-T, DVB-H) reception is developed. The Module by single conversion does divide a broadband($45MHz{\sim}860MHz$) broadcasting channels into three-bands(UHF, VHF_HIGH, VHF_LOW) to satisfy some electrical performances such as image signal rejection, phase noise, IF flatness etc and digital reception specifications such as analog and digital adjacent channel protection, co-channel protection which is important in environment with co-existence both analog and digital broadcasting systems.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.4
• /
• pp.624-632
• /
• 1994

In this paper, we implement modulator of 155Mbps 64QAM RF MODEM, CCITT G. 707 SDH(Synchronous Digital Hierachy) 1 level, for DMR(DIgital Microwave Radio) STM-1 transmission, PSF(Pulse Shaping Filter) plays an important role to analyze modulator. We use 7 orders elliptic filter instead of Chebychev filter(roll-off facter a=0.5)in this paper. we obtain that roll-off factor, a is 0.33, group delay is less than 10nsec using this filter. Also we get -20dBm output level after passing the PSF, and 0dBm output level after passing the IF amplifier.