• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1586-1592
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• 1999

In DWMT, CMFB is employed in the synthesis/analysis part. The CMFB uses filters of greater length than the DFT, resulting in reduced interference between the carriers. In addition, the CMFB system is computationally efficient and fast algorithms are available for their implementation. Traditional designs for the prototype filters of CMFB usually involve nonlinear optimizations. Thus the required design time is considerably large even for small filter orders. In this paper, a prototype filter design method for CMFB is presented using optimal window method. The design process is reduced to the optimization of a single parameter and consequently the required design time is much less than those of the existing methods. It is shown that the stopband performance of the proposed method is better than that of the Kaiser window method.

• 한국ITS학회:학술대회논문집
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• v.2006 no.10
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• pp.312-315
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• 2006

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.479-482
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• 1993

A fully balanced differential amplifier can achieve high-gain wide-bandwidth characteristics. And also, Offset PSRR, CMRR and Noise performance of that are excellent, but these merits can be achieved only when the architecture holds fully balanced. Commonly, the fully balanced differential amplifier has a common mode feedback(CMFB) circuit in order to maintain the balance. This paper presents improved characteristics of the CMFB circuit and designs the wide-bandwidth CMOS Op-amp. The unity gain bandwidth of this Op-amp is 50MHz with the load capacitor 2pF, and the value of phase margin is $85^{\circ}$.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.6
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• pp.1-8
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• 1999

Multi-carrier CDMA is a transmission scheme where data symbols are spread in the frequency domain with a spread code then transmitted using multiple carriers. It is robust against narrowband interference because of its long symbol duration. However, due to large sidebands of the rectangular window frequency response, subchannels spectrally overlap with neighboring subchannels, which leads to substantial intercarrier interference in a dispersive channel. In this paper, we consider a mult-carrier CDMA system where subchannel spectral containment is achiveved by M-band cosine modulated filter bank (CMFB). In CMFB based MC-CDMA, subchannel spectral containment is achieved using the filter bank of longer impulse response than that of conventional discrete Fourier transform (DFT) filter bank. We show that spectral containment feature of the CMFB based fading channel is analyzed using computer simulations.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.714-723
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• 2003

An effective technique to increase the signal swing and reduce noise is to use fully-differential -circuits. However, design of a common-mode feedback (CMFB) circuit that stabilizes the common-mode output level is essential. In this paper, a general description is given to fully-differential amplifiers with their CMFB loops, then a new error amplifier that is just composed of transistors and stabilizes the DC output level is proposed. We designed a simple and efficient bias circuit that allows the stability and maximum input swing. Simulation result shows the enhanced phase margin and increased differential-mode input swing with a proposed error amplifier.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.405-408
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• 2002

Because of superior division among sub-channels, DWT MC-CDMA is less interference with neighborhood channel. In our newly proposed multi-carrier CDMA data transmission method, lIR CMFB filter banks sharply divide sub-bands and reduces spectral overlaps among neighboring sub-channels. In experiment result, proposed filter is better ability of sub-band division than FIR filter. Since the proposed cosine modulated filter banks lIR filter having wavelet property is designed to response sharp transition band, the ISI and ICI between neighboring sub-channels can be effectively reduced. And robustness about narrow band interference of CMFB IIR MC-CDMA almost same FIR DWT MC-CDMA.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.6 s.360
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• pp.19-27
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• 2007

This paper presents power supply-insensitive Gbps low power LVDS I/O circuits. The proposed LVDS I/O has been designed and simulated using 1.8V, $0.18\;{\mu}m$ TSMC CMOS Process. The LVDS I/O includes transmitter and receiver parts. The transmitter circuits consist of a differential phase splitter and an output stage with the switched capacitor common mode feedback(SC-CMFB). The differential phase splitter generates a pair of differential signals which provides a balanced duty $cycle(50{\pm}2%)$ and phase difference$(180{\pm}0.2^{\circ})$ over a wide supply voltage range. Also, $V_{OD}$ voltage is 250 mV which is the smallest value of the permissible $V_{OD}$ range for low power operation. The output buffer maintains the required $V_{CM}$ within the permissible range$(1.2{\pm}0.1V)$ due to the SC-CMFB. The receiver covers a wide input DC offset $range(0.2{\sim}2.6\;V)$ with 38 mV hysteresis and Produces a rail-to-rail output over a wide supply voltage range. Beside, the designed receiver has 38.9 dB gain at 1 GHz, which is higher than conventional receivers.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.81-88
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• 2006

This paper describes a new linear operational transconductance amplifier (OTA). To improve the linearity of the OTA, we employ a mobility compensation circuit that combines the transistor paths operating at the triode and subthreshold regions. The common-mode control schemes consist of a common-mode feedback (CMFB) and common-mode feedforward (CMFF). The circuit enhances linearity of the transconductance (Gm) under the wide input voltage swing range. The proposed OTA shows ${\pm}1%$ Gm variation and the total harmonic distortion (THD) of below -73dB under the input voltage swing range of ${\pm}1.1V$. The OTA is implemented using a $0.35{\mu}m$ n-well CMOS process under 3.3V supply.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.871-876
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• 2010

Currently the development of powerline communication technology has become possible due to the high-speed communications. But the communication lines used for power line communication, not wires carrying power wiring is because when sending high-frequency wireless communication system unintentionally be influenced. To compensate for these shortcomings by using notch filters to reduce interference has been studied. Wavelet-based OFDM on the other hand by the method has been used to reduce interference. Wavelet-based OFDM has been used in the existing powerline OFDM scheme using FFT instead of the general structure of the CMFB filters to generate a signal. By doing so, subtly signals per frequency band, cut it, is to realize how efficient highways. It brought a deep filter characteristics, a flexible notch filter can be achieved without an external circuit has an advantage. In this paper, Using Wavelet OFDM powerline communication system is designed and presented the results of simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2C
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• pp.93-98
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• 2011

Currently, The new communication system was very important because of the increasing demand for Internet access. One of these alternatives is the PLC. But, Power Line is not suitable for communication. So, electromagnetic wave is generated from Power Line during flow of communication information. And the electromagnetic wave is interfered with Wireless Communication Service using the same frequency range. To eliminate this interference by used Notch tilter. Wavelet OFDM in another way, while one is used. In this paper, Wavelet OFDM CIC filter used in the CMFB structure by applying a further lowering the value of the side-lobe is proposed to improve performance.