• 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 Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.77-81
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• 2002

This paper demonstrates a CMOS downconversion mixer for 2.4GHz ISM band applications. The mixer, implemented in a 0.18um CMOS process, is based on the CMOS Gilbert Cell mixer, With a 2.5GHz local oscillator and a 2.45GHz RF input, the measurement results exhibit power conversion gam of -6dB, IIP3 of -6dBm, input $P_{-1dB}$ of -15 dBm, and power dissipation in mixer core of 2.7 mW with 0㏈m LO power and 1.8V supply voltage.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.270-273
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• 2003

The design, fabrication, and measured result of a 4.7 GHz differential VCO (Voltage Controlled Oscillator) for a 5.2 GHz WLAN (Wireless Local Area Network) applications is presented. The circuit is designed in a 0.35 mm technology employing three metal layers. The design is based on a fully integrated LC tank using spiral inductors. Measured tuning range is 10% of oscillation frequency with a control voltage from 0 to 3.0 V. Oscillation power of $\square$ 2.3 dBm at 4.63 GHz is measured with 21 mA DC current at 3V supply. The phase noise is $\square$ 104.17 dBc/Hz at 1 MHz offset.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.1
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• pp.74-81
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• 2004

We propose a novel scheme to transmit high center frequency RF signals using electroabsorption devices (EADs) as frequency converters at the transmitter and the receiver. In this approach frequency heterodyning is employed for obtaining high center frequency. With the EAD as a detector/mixer at the receiver we demonstrated a smaller conversion loss than that of the conventional modulator/mixer. With EAD as a modulator/mixer at the transmitter and with two heterodyned lasers to generate an optical local oscillator (LO), we demonstrated a large reduction (${\sim}23dB$) in conversion loss, and the transmission is not limited by the optical saturation of the EAD. This transmission scheme has optical single-side-band transmission feature which greatly relieves the fiber dispersion effect.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.247-251
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• 2001

본 논문에서는 MESFET을 이용하여 2670MHz에서 8010MHz로 주파수를 체배하는 Frequency Tripler를 설계 및 제작하였다. A급에 동작점을 두어 3차 하모닉 성분을 발생시켰고, λ$_{g}$/4 개방형 스터브와 대역통과 필터를 이용하여 기본주파수와 2차 하모닉성분을 억제하였다. 측정결과 0dBm의 입력신호에 대해 출력주파수인 8.16GHz에서 변환이득은 -0.33dB, -55dBc의 기본 주파수 억압, -33dBc의 2차 하모닉 성분의 억압을 얻었다. 2.5GHz～2.84GHz의 입력주파수에서 400MHz의 사용대역을 얻었다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.91-95
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• 2003

In this work, we have designed Gilbert cell downconversion mixer using 0.25um Anam CMOS process, we also have analyzed Conversion gain and IIP3 using Taylor series in our own unique way. Especially, bulk terminal is used as LO( Local Oscillator) input for reduction of power consumption and supply voltage. Supply voltage used in this design is lower than 1.8V and core current is less than 500uA. The simulation experiments showed that the conversion gain, IIP3, and power consumption were -1dB, 4.46dBm, and 0.8mW, respectively.

• The Journal of the Acoustical Society of Korea
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• v.14 no.6
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• pp.80-84
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• 1995

In the equivalent state with an actual transmission, the paper is presented the novel analysis of the dynamic characteristics of the automatic frequency control, using for QPSK relay system in digital land mobile communication, which is adopted a crass product frequency discriminator and the various kinds of frequency variances that calculate the closed loop frequency jitter are found.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.6
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• pp.272-275
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• 2004

A balanced single side-band (SSB) mixer employing a sub-harmonic configuration is designed for up and down conversions in K-band. The designed mixer uses anti-parallel diode (APD) pairs to effectively eliminate even harmonics of the local oscillator (LO) spurious signal. To reduce the odd harmonics of LO at the RF port, we employ a balanced configuration for LO. The fabricated chip shows 12$\pm$2dB of conversion loss and image-rejection ratio of about 20dB for down conversion at RF frequencies of 24-27.5GHz. As an up-conversion mode, the designed chip shows 12dB of conversion loss and image-rejection ratio of 20 ～ 25 dB at RF frequencies of 25 to 27GHz. The odd harmonics of the LO are measured below -37dBc.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.598-603
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• 1990

This study evaluates the performance of an optical receiver for binary phase shift keying (BPSK) signals in the presence of short noise originating from the photo diode and phase noise of the optical source. The case of using I.O. hybrid compare with the fiber optic hybrid to mix received optical signal and laser local oscillator signal. The impact of these noise is minimized if loop natural frequency and power split ratio between data and carrier recovery branch are choosen optimally. Then it is obtained that required laser linewidt to achieve a BER of 10**-9. The results are the same except theat in case of using the fiber optic hybrid the required optical power is twice as much as the I.O. hybrid.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1681-1684
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• 2002

A multilevel modulation with selectable constellations is adopted in the downlink subframe modulation of the IEEE 802.16 standard to increase the total throughput. One of the decision factors of the modulation is the location of SS(Subscriber Station) . Also, for the 802.16, low phase noise of local oscillator is needed due to high operating frequency and severe loss in the propagation channel. We investigate the BER of down-link subframe with the phase jitter under the standard's specified LOS(line of sight) and multipath environment with randomly generated SS locations. Simulation results show BER performance degradation for the modulation corresponding to selected constellations and additionally required SNR to achieve 10$\^$-3/ BER under various phase jitter.