應用於可見光通訊具有主動降低電磁干擾技術之LED驅動器

本篇論文提出應用於可見光通訊並具有主動降低電磁干擾技術之LED驅動器，此系統是基於升壓式直流-直流轉換器為主要架構。可見光通訊有許多競爭優勢優過於RF，其中包含廣闊的頻寬、安全性、功耗低以及美學。本LED驅動器符合日本可見光通訊協會(JEITA CP-1222)所訂定之標準來做設計，其採用振幅調變(ASK)的方式將資料做傳送。我們使用了展頻的技術來降低電磁干擾。有別於一般使用DSP或MCU的解決方案，在晶片內我們使用了一個10階的LFSR來實現擬似隨機訊號的產生，並利用其中四個最低有效位元來調變PWM訊號之頻率。使得其時脈的頻譜被展開後，能量頻譜密度及EMI都得以下降。本系統之實現使用臺積電0.35-μm CMOS製程，晶片大小為1.3#westeur024#1.4平方毫米。其量測結果顯示可以降低14分貝的電磁干擾同時也可提供峰對峰值(0到120毫安培)的驅動電流，載子頻率約為830kHz並且其資料的傳輸速率可達140kbps。

關鍵字

電磁相容；電磁干擾； LED驅動器；切換式電源供應器；直流-直流升壓轉換器

並列摘要

This paper proposed an LED driver with active EMI mitigation for visible light communication (VLC). The system is based on a DC-DC boost converter with EMI mitigation scheme. VLC have a variety of competitive advantages over RF, including high bandwidth density, security, energy consumption, and aesthetics. The proposed LED driver complies with the standard of Japan Electronics and Information Technology Industries Association (JEITA CP-1222). It employs ASK modulation for data transmission. The EMI mitigation is achieved by the spread spectrum techniques. Different from most of the solutions which used on-board DSP or MCU, we implemented an on-chip 10th-order LFSR to generate pseudo-random vectors. The four LSBs are used to modulate the clock's frequency, such that the resulting clock spectrum is spread and the corresponding power spectral density as well as EMI are reduced. The system is implemented in the TSMC 0.35μm CMOS process with the die size of 1.3#westeur024#1.4 mm2. The measurement results show that the proposed mitigation scheme can reduce the EMI by 14 dB while provide peak-to-peak (0 - 120 mA) driven current. The carrier frequency is about 830 kHz and the data rate is up to 140 kbps.

並列關鍵字

EMC ； EMI ； LED Driver ； Switch-mode Power Supply ； DC-DC Boost Converter

參考文獻

[1] Krishna Mainali, and Ramesh Oruganti, “Conducted EMI Mitigation Techniques for Switch-Mode Power Converters: A Survey,” IEEE Transactions on Power Electronics, vol.25, no.9, pp.2344-2356, Sept. 2010.

[5] Hong-Wei Huang; Chun-Yu Hsieh; Ke-Horng Chen; Sy-Yen Kuo, "Load Dependent Dead-Times Controller Based on Minimized Duty Cycle Technique for DC-DC Buck Converters," Power Electronics Specialists Conference, vol., no., pp.2037-2041, 17-21 June 2007.

[6] S. Rajagopal, Richard D. Roberts and Sang-Kyu Lim, “IEEE 802.15.7 Visible Light Communication: Modulation Schemes and Dimming Support,” IEEE Communications Magazine, March 2012.

[7] Christian Phohlmann, “Visible Light Communication,“ June 2010. http://www-old.itm.uni-luebeck.de/

[11] Feng Lin, and Dan Y. Chen, “Reduction of Power Supply EMI Emission by Switching Frequency Modulation,” IEEE Transactions on Power Electronics, vol.9, no.1, pp.132-137, Jan 1994.

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應用於可見光通訊具有主動降低電磁干擾技術之LED驅動器

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