Power-Efficient VLC Transmitter Able to Reproduce Multi-Carrier Modulation Schemes by Using the Output Voltage Ripple of the HB-LED Driver

Visible Light Communication (VLC) consists in using High-Brightness LEDs (HB-LEDs) not only for lighting, but also for transmitting information by changing the light intensity rapidly. One of the most important problems of VLC is that the HB-LED drivers that have been proposed for achieving the highest bit rates offer low power efficiency. The reason is that since these HB-LED drivers must be able to reproduce fast current waveforms, the use of Linear Power Amplifiers (LPAs) has been adopted, which damages the power efficiency of HB-LED lighting. To the author's knowledge, there is only one approach reported in the literature that is able to reproduce the most recommended modulation schemes by using a power efficient HB-LED driver. However, since it is based on the use of pulse-width modulated dc-dc power converters, the required switching frequency is between 3 and 6 times higher than the maximum frequency of the communication signal. As a result, the approach suffers from high switching losses when the highest bandwidths are addressed. A method for reproducing the most recommended modulation schemes by modulating both the amplitude and the phase of the output voltage ripple is presented in this work. The major benefits are the high efficiency, the simplicity and the lower switching frequency required for the implementation.