• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.845-848
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• 2005

This paper describes a 4.224GHz CMOS charge pump PLL for Mode 1 MB-OFDM UWB hopping carrier generation. It includes a qudrature VCO of which the frequency range is from 3.98GHz to 4.47GHz(@ 0.4 to 1.5 V), a divider, a PFD, a loop filter, a charge pump, and a lock detector. Designed in a 0.18um CMOS technology, the PLL draws 6.6mA from a 1.8V supply. The phase noise of the designed VCO is -133dBc/Hz@3MHz.

• ETRI Journal
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• v.32 no.1
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• pp.1-10
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• 2010

In this paper, we present a fast Fourier transform (FFT) processor with four parallel data paths for multiband orthogonal frequency-division multiplexing ultra-wideband systems. The proposed 128-point FFT processor employs both a modified radix-$2^4$ algorithm and a radix-$2^3$ algorithm to significantly reduce the numbers of complex constant multipliers and complex booth multipliers. It also employs substructure-sharing multiplication units instead of constant multipliers to efficiently conduct multiplication operations with only addition and shift operations. The proposed FFT processor is implemented and tested using 0.18 ${\mu}m$ CMOS technology with a supply voltage of 1.8 V. The hardware- efficient 128-point FFT processor with four data streams can support a data processing rate of up to 1 Gsample/s while consuming 112 mW. The implementation results show that the proposed 128-point mixed-radix FFT architecture significantly reduces the hardware cost and power consumption in comparison to existing 128-point FFT architectures.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.225-227
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• 2012

무선 사운드 스피커는 서로 다른 위치에 배치되어 송신기와의 채널 환경이 서로 다르게 되어 송신기와의 거리가 상대적으로 먼 후방 스피커의 경우 사람이나 구조물에 의해 채널 환경이 열악하게 되어 전방 스피커에 비해 데이터 오류 발생 확률이 높다. 본 논문은 Multi-band orthogonal frequency division multiplexing (MB-OFDM) 기반의 무선 오디오 전송 시스템에서 무선 채널 환경이 우수한 스피커에서 무선 채널 환경이 열악한 스피커로 데이터를 전달하는 스피커 릴레이 기법을 사용할 때, packet error ratio (PER) 성능을 향상시키며 전송 시간을 감소시킬 수 있는 효율적인 스피커 릴레이 기법을 제안한다.