科研之友
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摘要
Recent breakthroughs in solid-state lighting technology have opened the door to a variety of applications using light-emitting diodes (LED's) for not only illumination, but also optical wireless communication. Low-power CMOS technology enables realization of system-on-chip driver circuits integrating multiple functions to control LED device performance, luminance, and data modulation for "intelligent" visible light networking. This paper presents an LED driver circuit architecture, incorporating analog and digital circuit blocks to deliver concurrent dimming control, and data transmission. This is achieved by independent control of output voltage and current using buck converter and current control loops, respectively. This integrated system incorporates the feedback mechanisms to provide uniform light output together with the peak current control, which also prevents flickering. The proposed architecture is flexible enough to take any digital base band modulation format. Designed and implemented in a 180 nm CMOS process, it provides linear 10-90 % dimming control while transmitting data. It also introduces a mechanism which can be applied to the off-the-shelf LED drivers and make them applicable for the visible light communication applications. The power consumption of on-chip circuitry, is negligible compared to the overall power consumption which yields an efficiency of 89 % at 120 mA of load current. The measured bit error rate (BER) varies from 10(-6) at the data rate of 2.5 Mbps to 10(-2) at the data rate of 7 Mbps. All control functions integrated on-chip with the total power consumption of 5 mW.
- 出版日期2014-8
