Preemphasis Control in Switched-Mode Power Converter for Energy-Efficient Wide Bandwidth Visible Light Communication

Visible light communication (VLC) shows up as a trend for short-range wireless networks. However, from the energy point of view, there is still a lack of light-emitting diode (LED) drivers that support considerable data rates with high efficiency. Common solutions would include switched-mode power converters (SMPCs), which are efficient, but they still face challenges regarding the modulation bandwidth (BW) for VLC. Thus, this article presents an analysis of a preemphasis (PE) technique to overcome the low BW constraint of the SMPC. The PE filter is used to render the frequency response of the circuit to provide a wider BW for communications. It operates on the duty cycle of the converter, and it dictates the average output signal value over a switching period. Finally, the technique is presented in a theoretical approach with the aligned experimental results in a 21.5-W buck-converter-based LED driver switched at 1 MHz, with 89% efficiency and an increased modulation BW from 8.12 to 450 kHz (55 times).