• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.2
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• pp.147-155
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• 2002

This paper describes RF front-end transceiver chipset for the dual-mode operation of PCS-Korea and IMT-2000. The transceiver chipset has been implemented in a $0.25\mutextrm{m}$ single-poly five-metal CMOS technology. The receiver IC consists of a LNA and a down-mixer, and the transmitter IC integrates an up-mixer. Measurements show that the transceiver chipset covers the wide RF range from 1.8GHz for PCS-Korea to 2.1GHz for IMT-2000. The LNA has 2.8~3.1dB NF, 14~13dB gain and 5~4dBm IIP3. The down mixer has 15.5~16.0dB NF, 15~13dB power conversion gain and 2~0dBm IIP3. The up mixer has 0~2dB power conversion gain and 6~3dBm OIP3. With a single 3.0V power supply, the LNA, down-mixer, and up-mixer consume 6mA, 30mA, and 25mA, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.998-1004
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• 2002

This paper reports a design of feedforward linear power amplifier using pilot tone for IMT-2000 band repeaters accepting multi-carrier. As this time pilot tone is applied to the circuit differently from the existing method. Only one pilot tone is used in both 1-st loop(IMD abstraction loop) and 2-nd loop(IMD cancellation loop) to cancell IMD signals automatically according to variation of frequency or power level of input signals. As an experiment, in range of 2110 MHz - 2170 MHz at LPA output power of $20 W_{avg}$, IMD characteristics of over 20 dB was improved maintaining below -60 dBc considering respective 20 MHz. Therefore the supposed feedforward linear power amplifier can be used for linear power amplifier in IMT-2000 band repeaters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.1 s.92
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• pp.66-77
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• 2005

This paper proposed a novel broadband PIFA(Planar Inverted-F Antenna) for IMT-2000/WLAN/DMB terminal. Two branch lines for meander line were utilized in order to improve the characteristics of PIFA which usually has a narrow band. The shorting strip between the ground plane and meander-type radiation elements were used in order to minimize the size of the antenna. The -10 dB return loss bandwidth of a realized antenna was $38.2{\%}$(1.84~2.71 GHz), which contains the broadband bandwidth with triple band. And the simulated and measured values of 1 g and 10 g averaged peak SAR on human head caused by the triple band PIFA mounted on folder-type handsets were analyzed and discussed. As a result, the measured 1 g and 10 g averaged peak SARs of PIFA were similar with the simulated values and were lower than the 1.6 W/kg and 2 W/kg of 1 g and 10 g averaged peak SAR limits.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1233-1239
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• 2008

In this paper we proposed a novel broadband printed monopole antenna for PCS/IMT-2000/WLAN terminals by widening current flow To compensate narrow bandwidth characteristics which is one of disadvantages of general printed monopole antenna, we add the patch of diamond shape and induce the current in various directions for acquiring broadband characteristics. And frequency characteristics is optimized with Various design parameters. The bandwidth of the realized antenna is $1.66{\sim}3.04\;GHz$(58.72 %) below the return loss of -10 dB which contain the required band-width of PCS/IMT-2000/WLAN band.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.4
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• pp.409-412
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• 2002

The LNA(Low Noise Amplifier) is designed for use in low cost commercial application covered fully IMT-2000 band(1920~2170MHz, BW=250MHz). It is optimized source inductance for source lead and designed to equivalent etched line. The LNA uses a high pass impedance matching network for noise match and simple structure. The bias circuit designs have been made self-biased with a negative voltage applied to gate. The power supply voltage is 8V, total current is 180mA. The LNA is biased at a Vgs of -0.4, Vds of 4V for first stage and Vds of 5V for second stage. The LNA is designed competitively for commercial product specification. The measured gain and noise figure of the completed amplifier was 20dB and 1dB, respectively. Also, input VSWR, P1dB and gain flatness was measured of 1.14 ~ l.3dB, 22.4dBm and $\pm$0.45dB, respectively. The designed LNA can be used for commercial product.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.882-889
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• 2001

In this paper, the characteristics of u-slot antennas are computed by changing the feed structure, and compared with the measured results. The impedance bandwidths of 13 %(255.1 MHz) and 30.7 %(602.1 MHz) are obtained for probe feed and L-strip feed, respectively. It is known that the designed L-strip feed can be used for increasing the bandwidth of u-slot antennas. In addition, it is shown that the designed L-strip feed u-slot antenna can be used for domestic PCS and IMT-2000 dual band applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.242-250
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• 2004

In this thesis, a new broadband PIFA(Planar Inverted-F Antenna) for PCS and IMP-2000 applications is designed. The dual-L antenna structure is adopted in order to improve the characteristics of PIFA which usually has a narrow band. The height of the antenna is fixed 6 mm considering terminal's thickness and the structure is deformed into the folded radiation patches to minimize the size of the antenna. The bandwidth of a realized antenna is 1.66∼2.35 ㎓(34.5 %) fur return loss below -10 ㏈ which contain the required bandwidth of PCS and IMT-2000. And Monopole antenna with λ/4 length is designed and compared with dual-L with folded patch in SAR. 1 g and 10 g averaged peak SAR of PIFA are about 25.7 %, 30.3 % lower than those of monopole antenna respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.359-362
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• 2002

The increase in the number of PCS base station and repeater has increased the level of interference between PCS carriers. In this paper, interference of singular PCS repeater out-of-band noise power on mobile phone is analysed and compared with that of unified PCS repeater for multiple PCS carriers. It is shown that unified PCS repeater provide about 2∼3dB signal gain in comparison with conventional PCS repeater. As a result, the interference of out-of-band noise power on mobile phone is reduced. It is expected that PCS carriers are able to build an environmentally-friendly communications infrastructure and reduce the cost by using unified PCS revealer and apply it for the deployment of IMT-2000 network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.147-152
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• 2005

In this paper, we have proposed a novel DGS(Defected Ground Structure) resonator and has designed the band -pass filter using the proposed ${\subset}$ stub-I type DGS resonator. This structure has strong advantages that can vary the retune loss at the passband freely and also can easily tune the attenuation pole frequency at the stopband. The bandpass filter can be made more smaller than the existing filters and be used to find the various applications for eliminating the harmonics and spurious mode at IMT-2000 band.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.374-379
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• 2010

In this paper, we have mathematically analyzed lumped element type negative group delay circuit (NGDC) and derived general design equation. The applicability of the proposed design equation is validated with mathematical and circuit simulation as well as with experimental results for intentional mobile telecommunication 2000 (IMT-2000) downlink band. As a design example, single branch NGDC with -0.8ns of group delay (GD) for narrow bandwidth of the specific frequency is simulated and fabricated. Finally, $\pi$-network NGDC is proposed and validated to obtain wideband GD response of $-1.7{\pm}0.06$ nsec for 60 MHz.