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1-비트 4차 델타-시그마 변조기법을 이용한 D급 디지털 오디오 증폭기
강경식(Kyoungsik Kang),최영길(Youngkil Choi),노형동(Hyungdong Roh),남현석(Hyunseok Nam),노정진(Jeongjin Roh) 대한전자공학회 2008 電子工學會論文誌-SD (Semiconductor and devices) Vol.45 No.3
본 논문에서는 휴대용 오디오 제품의 헤드폰 구동을 위한 델타-시그마 변조기법 기반의 D급 증폭기를 제안한다. 제안된 D급 증폭기는 고성능 단일 비트 4차 델타-시그마 변조기를 이용하여 펄스폭 변조 신호를 발생 시킨다. 높은 신호 대 잡음비를 얻는 것과 동시에 시스템의 안정성 확보를 위하여 시뮬레이션을 통해 변조기 루프필터의 폴과 제로를 최적화 하였다. 테스트칩은 0.18㎛ CMOS 공정으로 제작 되었다. 칩 면적은 1.6㎟ 이며, 20㎐ 부터 20㎑까지의 신호대역을 대상으로 동작한다. 3V 전원전압과 32옴의 로드를 사용하여 측정된 출력은 0.03% 이하의 전고조파 왜율을 갖는다. In this paper, we present the design of delta-sigma modulation-based class-D amplifier for driving headphones in portable audio applications. The presented class-D amplifier generates PWM(pulse width modulation) signals using a single-bit fourth-order high-performance delta-sigma modulator. To achieve a high SNR(signal-to-noise ratio) and ensure system stability, the locations of the modulator loop filter poles and zeros are optimized and thoroughly simulated. The test chip is fabricated using a standard 0.18㎛ CMOS process. The active area of the chip is 1.6㎟. It operates for the signal bandwidth from 20㎐ to 20㎑. The measured THD+N(total harmonic distortion plus noise) at the 32Ω load terminal is less than 0.03% from a 3V power supply.
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김홍준(Kim Hongjun),강경식(Kang Kyoungsik),최고야(Choi Goya),김호경(Kim Hokyung),정승일(Jeong Seungil),주영승(Ju Youngsung) 한국한의학연구원 2006 한국한의학연구원논문집 Vol.12 No.3
The purpose of this study was to introduce the differential standard of Mok-Hyaeng Radix species. We established the classificatory standard according to the external and internal morphology and the pattern in 4 kinds of Mok-Hyaeng Radix. The results follow: 1. On the external morphology, Radix of Vladimiria souliei had a sticky material in the head of roots and it was yellowish white in the cut surface. It attached to teeth during chewing. Radix of Aucklandia lappa (=Saussurea lappa) was dark grayish brown and was grayish brown in the cut surface. It had special odor and was not attache to teeth chewing it. On the other hand, Radix of Inula helenium was dark brown. In the cut surface, cortical layer was different from wood layer. Radix of Aristolochia contorta was yellowish brown. In the cut surface, it was not smooth and cortical layer was different from wood layer. 2. On the internal morphology, Radix of Vladimiria souliei had many fascicular fibers and scattered large oil chambers in the bast ray, xylem ray, and parenchyma. On Radix of Aucklandia lappa (=Saussurea lappa), it was difficult to find out the trace when the cork layer was exfoliated. The cambium formed circle and the large oil chambers were scattered in the phloem and xylem On the other hand, external cortical layer of Radix of Inula helenium was detached and cambium was formed to indistinct circle and large oil chambers were scattered in the phloem and xylem. On Radix of Arustolochia contorta, the large oil chambers were scattered in the surface layer, bast part was relatively broad and cambium formed circle. 3. On the TLC pattern, Radix of Aristolochia contorta, Inula helenium; Aucklandia lappa, and Vladimiria souliei were chromogenic to violet and purple according to sulfuric acid colour pattern, especially faint on Aristolochia contorta. 4. On the pattern analysis of HPLC, we compared the content and the pattern of constunolide and dehydrocostus lactone, Radix of Aucklandia lappa was similar to Radix of Vladimiria souliei and Radix of Aristolochia contorta was similar to Radix of Inula helenium. On the total HPLC component pattern, constunolide and dehydrocostus lactone were similar in all four types, but it showed the Rf 5-6 peak was only in Radix of Aristolochia contorta, not in Radix of Inula helenium, AuckLandia lappa, and Vladimiria souliei. It is considered the results of this study will be furnished the basis to succeeding studies and it is needed to extensive comparative study for the same genus-degree of relatedness.
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