• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.16-20
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• 2002

This paper describes the resistive FET mixer with low IF for the 4-Ch DBF(Digital Beam Forming) receiver with LNA(Low Noise Amplifier). 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 ㎓, 2.08 ㎓ and 10㎒, respectively. The RF input power, LO input power and Vgs are used -10㏈m, 6㏈m and -0.4 V, respectively. In the 4-Ch resistive FET mixer with LNA, the measured IF and harmonic components of 10㎒, 20㎒, 2.09㎓ and 4.17㎓ are about -12.5 ㏈m, -57㏈m, -40㏈m and -54㏈m, respectively. The IF output power observed at each channel of 10㎒ is about -12.5㏈m and it is higher 27.5 ㏈m than the maximum harmonic component of 2.09㎓. Each IF output spectrum of the 4-Ch is observed almost same value and it shows a good agreement with the prediction.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.615-616
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• 2006

Nowadays, the need of multi-mode/multi-band transceiver is rapidly increasing, so we design a direct conversion RF front-end for multi-mode/multi-band receiver that support WCDMA/CDMA2000/WIBRO standard. It consists of variable gain reconfigurable LNA and single input double balanced Mixer and complementary differential LC Oscillator. The circuit is implemented in 0.18 um RF CMOS technology and is suitable for low-cost mode/multi-band.

• ETRI Journal
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• v.30 no.1
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• pp.33-46
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• 2008

This paper presents the experimental results of a low-power low-cost RF transceiver for the 915 MHz band IEEE 802.15.4b standard. Low power and low cost are achieved by optimizing the transceiver architecture and circuit design techniques. The proposed transceiver shares the analog baseband section for both receive and transmit modes to reduce the silicon area. The RF transceiver consumes 11.2 mA in receive mode and 22.5 mA in transmit mode under a supply voltage of 1.8 V, in which 5 mA of quadrature voltage controlled oscillator is included. The proposed transceiver is implemented in a 0.18 ${\mu}m$ CMOS process and occupies 10 $mm^2$ of silicon area.

• 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.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.3
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• pp.381-389
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• 2015

A fully integrated multistandard multiband CMOS mobile TV tuner with small silicon area and low power consumption is proposed for receiving multiple mobile digital TV signals and FM signal. In order to reduce the silicon area of the multistandard multiband receiver, other RF front-end circuits except LNAs are shared and a local oscillator (LO) signal generation architecture with a single VCO for a frequency synthesizer is proposed. To reduce the low frequency noise and the power consumption, a vertical NPN BJT is used in an analog baseband circuits. The RF tuner IC is implemented in a $0.18-{\mu}m$ CMOS technology. The RF tuner IC satisfies all specifications for DVB-H/T, T-DMB, and ISDB-T with a sufficient margin and a successful demonstration has been carried out for DVB-H/T, T-DMB, and ISDB-T with a digital demodulator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.412-418
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• 2002

In this paper, the authors present the simulation results and the experimental considerations on the effects of the effects of the VCO oscillation characteristics caused by varying the length of the MSL and the composition capacitance of LC resonation circuity. Simulation was accomplished by nonlinear RF circuit simulator for designing and analyzing the RF characteristis of VCO. The samples with 3 different MSL lengths of which the length is 140mil, 280mil and 560mil respectively were fabricated by screen printing process. The oscillation frequency of each sample(VCO) was tuned to UHF band (750MHz~900MHz) by varying the capacitance of LC resonator circuit. The experimental results showed that the values of phase noise were -82, -93, -97[dBc/Hz] at 50[kHz] offset frequency, the pushing figures were 114, 94, 318[kHz] at applied voltage of $3\pm0.15$[V] and the harmonics were -21, -16, -13[dBc] for MSL lengths of 140mil 280mil, 560mil respectively. The frequency and output variation width were 779~898[MHz], -36~-33[dBm] for MSL with 140mil length; 818~836[MHz], -27.19~27.06[dBm] for 280mil; 751.54~751.198[MHz], -33.44~-33.31[dBm] for 560mil.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.7-11
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• 2014

In this paper, we designed resistive MMIC mixer using $0.5{\mu}m$ p-HEMT process. This Mixer is designed to have a similar performance in -4 ~ 4 dBm local oscillator signal power level and to maintain a constant conversion loss and linear performance due to the variation of local signal. In order to have such characteristics, we designed new feedback circuit topology by using FET, and minimized performance change for LO signal power level variation, also obtain MMIC mixer characteristics which is able to apply in wideband. In the design result, When the LO signal power is -4 ~ 4 dBm, there was 6 dB conversion loss and it came up with the excellent result that IIP3 got over 30 dBm in 0.5 ~ 2.6GHz frequency band.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.4
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• pp.243-248
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• 2015

Since phase noise is one of the most important parameters in the design of microwave oscillators, several methods have been proposed to reduce the phase noise. These methods have focused on improving the quality factor of resonators, which result in low phase noise oscillators. Dielectric resonators have been widely used for low phase noise in microwave oscillators due to their high quality factor. However this cannot be used in MMIC oscillators because they have a 3D structure. In this paper, to overcome this problem a novel resonator using open ring type DGS is proposed for improvement of phase noise characteristics that is weak point of oscillator using planar type microstrip line resonator, and oscillator for 5.8GHz band is designed using proposed DGS resonator. The open ring type DGS resonator is composed of DGS cell etched on ground plane under $50{\Omega}$ microstrip line. At the fundamental frequency of 5.8GHz, 6.1dBm output power and -82.7 dBc@100kHz phase noise have been measured for oscillator with ring type DGS resonator. The phase noise characteristics of oscillator is improved about 96.5dB compared to one using the general ${\lambda}/4$ microstrip resonator.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.715-720
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• 2012

This study presents a hybrid balanced voltage controlled oscillator (VCO) circuit which is suitable for low phase noise operation at sub-1V supply voltages. Half circuits of the proposed VCO use the varactor-integrated feedback capacitors in their respective circuit. The varactor-integrated feedback capacitors further increase the negative resistance of the equivalent tank thereby ensuring stable start-up of oscillation even at the sub-1V supply voltage. In addition, this work theoretically analyses the phenomenon of the increase of the negative resistance. Simulation results using a $0.18{\mu}m$ RF CMOS technology exhibit the phase noises of -122.4 to -125.5.8 dBc/Hz at 1 MHz offset from oscillation frequency of 4.87 GHz over the supply voltages of 0.6 through 0.9 V.

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