• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.97-102
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• 2018

In this paper, W-band Waveform Generator for compact radar has been designed and fabricated. DDS (Direct Digital Synthesizer) is applied to generate CW (Continuous Wave) and FMCW (Frequency Modulation Continuous Wave) waveform at high speed. We designed two LO (Local Oscillator) paths for functions of distance delay and distance tracking tests at the prpposed system without extra test equipment. Two mode selections are provided by switch. It is observed that fabricated waveform generator performs -91 dBc/Hz phase noise at offset 1 kHz and -63.2 dBc spurious. Proposed W-band Waveform Generator is expected to apply for W-band compact radar transceiver module.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1312-1315
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• 2002

This research describes the design of a fully integrated fractional-N frequency synthesizer intended for the local oscillator in IMT-2000 system using 0.18-$\mu\textrm{m}$ CMOS technology and 1.8-V single power supply. The designed fractional-N synthesizer contains following components. Modified charge pump uses active cascode transistors to achieve the high output impedance. A multi-modulus prescaler has modified ECL-like D flip-flop with additional diode-connected transistors for short transient time and high frequency operation. And phase-frequency detector, integrated passive loop filter, LC-tuned VCO having a tuning range from 1.584 to 2.4 ㎓ at 1.8-V power supply, and higher-order sigma-delta modulator are contained. Finally, designed frequency synthesizer provides 5 ㎒ channel spacing with -122.6 dBc/Hz at 1 ㎒ in the WCDMA band and total output power is 28 mW.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.90-98
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• 1999

This paper presents a wideband single-balanced mixer using a diode which can be used in RF receiver of microwave measurement systems. For wideband characteristic, local oscillator(LO) signal is provided to diode with low loss using a coplanar waveguide-to-slotline balun. For high isolation characteristic radio frequency (RF) port and intermediate frequency (IF) port are designed using directional coupler. This mixer presents 30.5~31.17dB conversion loss whose flatness is within 1dB for 9 kHz~2.6 GHz wideband RF signal, and above 30 dB isolation for LO signal.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.219-223
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• 2003

This paper describes an estimation of DOA(Direction Of Arrival) measurement system using DBF receiver with linear array antenna. This DBF receiver is composed of resistive FET mixer using low IF mettled. A radio frequency(RF), a local oscillator(LO) and ail intermediate frequency(IF) considered in this research are 2.09 GHz, 2.08 GHz and 10 MHz, respectively. This receiver is composed of a band-pass filter, a low-pass filter, a DC bias circuit. DOA measurement system is consist of linear array antenna, DBF receiver, AD control box and computer in the anechoic chamber. Receiving antenna is 4-array monopole antenna and DBF receiver is 4-Ch resistive FET mixer without amplifier. DOA algorithm is implemented using MUSIC algorithm with high resolution. We show that the results of DOA is $-30^{\circ},\;0^{\circ}$ and $60^{\circ}$, respectively. And we know that DOA estimation error occur by antenna radiation pattern and fabrication error of antenna array.

• Journal of Navigation and Port Research
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• v.28 no.1
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• pp.37-41
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• 2004

In this paper, a reflector type frequency doubler for local oscillator at 24GHz is designed and fabricated with ne71300-N MESFET. Optimum source and load impedances are decided through a multiharmonic load pull simulation technique. A conversion gain can be improved using the reflector and fundamental and third harmonics are well suppressed with open stub of $\lambda$/4 length Measured results show output power at 0dBm of input power is -3.776dBm, conversion gain 0.736dB, harmonic suppression 41.064dBc, respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.1
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• pp.37-49
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• 2008

At the present time the task of designing a highly integrated ZigBee radio frequency (RF) receiver with an excellent coexistence performance is still very demanding and challenging. This paper presents a number of system issues and design considerations for a ZigBee RF receiver, namely IEEE 802.15.4, for coexistence with wireless devices in the 2.4-GHz ISM-band. With regard to IEEE 802.15.4, the paper analyzes receiver performance requirements for; system noise figure (NF), system third-order intercept point (system-IIP3), local oscillator phase noise and selectivity. Based on some assumptions, the paper illustrates the relationship between minimum detectable signal (MDS) and various situations that involve the effects of electromagnetic interference generated by other wireless devices. We infer the necessity of much more stringent specification requirements than the published standard for various wireless communication field environments

• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.117-123
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• 2002

This paper describes the design for the resistive FET mixer with low If for the 4-Ch DBF(Digital Beam Forming) receiver This DBF receiver based on the direct conversion method is generally suitable for high-speed wireless mobile communications. A radio frequency(RF), a local oscillator(LO) and an intermediate frequency(If) considered in this research are 2.09 GHz, 2.08 CHz and 10 MHz, respectively. This mixer is composed of band pass filter, a low pass filter and a DC bias circuit. Super low noise HJ FET of NE3210S01 is considered in design. The RE input power, LO input power and Vcs are used -10 dBm, 6 dBm and -0.4 V, respectively. In the 4-Ch resistive FET mixer, the measured If and harmonic components of 10 MHe, 20 MHz and 2.087 CHz are about -19.2 dBm, -66 dBm and -48 dBm, respectively The If output power observed at each channel of 10 MHz is about -19.2 dBm and it is higher 28.8 dBm than the maximum harmonic component of 2.087 CHz. Each If output spectrum of the 4-Ch is observed almost same value and it shows a good agreement with the prediction.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.959-968
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• 2000

In this paper, a low phase noise frequency synthesizer used to TX local oscillator in BWLL RF tranceiver is presented. The phase-locked stable 25GHz-band frequencies in BWLL TX LO are obtained by using 2 GHz baseband frequency synthesizer, sixth-harmonic frequency multiplier and frequency doubler at 12 GHz band frequency input. The 25 GHz band frequency synthesizer presented in this paper has 3-output frequencies at 24.92 GHz, 25.10 GHz, 25.26 GHz. At 24.92 GHz frequency the synthesizer has 0.44 dBm output power and shows -87.93 dBc/Hz(a 10 KHz), -109.54 dBc/Hz (a100 KHz) phase noise characteristics .

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.219-226
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• 2007

In this paper, we report phase noise effects on SER(Symbol Error Rate) of MQAM(M-ary Quadrature Amplitude Modulation), DPSK(Differential Phase Shift Keying), OFDM(Orthogonal frequency Division Multiplex)-MQAM and OFDM-DPSK. SER of each modulation method has been quantified at the various offset frequencies of the local oscillator and compared with phase noise effects with the ideal cases, which have no phase noise, through the MATLAB simulation. And the ratio of modulation bandwidths to the SERs at the various frequency offsets for the above modulation methods have been analyzed for the system requirement of minimum phase noise characteristics.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.491-492
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• 2006

The MMIC (Microwave Monolithic Integrated Circuit) self oscillating double conversion mixer was designed and fabricated for the V-band transmitter applications. The MMIC self oscillating double conversion mixer which dose not need external local oscillator was designed using GaAs PHEMT technology. The first self oscillating mixer use PHEMT technology. The first self oscillating mixer use PHEMT for $f_{LO}$ signal generation and $f_{IF}$ signal is applied at gate port and $f_{RF1}$ signal is generated at a drain port of first stage. The second gate mixer use PHEMT for $f_{LO}$ signal and $f_{RF1}$ signal is applied at gate port and $f_{RF2}$ signal is output at a drain port of second stage.