A Novel Version of the Ripple-Modulation Technique for Enabling the Use of Single-Phase Buck Converters in VLC Applications

Visible light communication (VLC) has recently emerged as a promising technology for alleviating the saturation of the radio frequency (RF) spectrum. VLC uses high-brightness light-emitting diodes (HB-LEDs) both for lighting and communication. In particular, the information transmission is carried out by performing fast changes of the light intensity emitted by the HB-LEDs. The conventional VLC driver includes a linear power amplifier (LPA) for reproducing the communication signal. Unfortunately, this approach penalizes the efficiency. During the last years, a wide variety of VLC drivers fully based on the use of switching-mode power converters (SMPCs) have been proposed to overcome the efficiency limitation. One of the most promising approaches is the ripple-modulation (RM) technique, which consists in using the output voltage ripple of an SMPC to reproduce the communication signal. However, the conventional RM technique has a major drawback: it can only be applied to multiphase buck converters. This work is focused on overcoming that limitation by introducing a novel version of the RM technique that enables the use of a single-phase buck converter. In this way, the work aims to reduce the required power-stage complexity, which is a critical parameter of HB-LED bulbs. Moreover, a novel output filter structure is proposed to reduce the total harmonic distortion of the reproduced signal. A ripple-modulated buck converter prototype was built with an output power and a switching frequency of 8 W and 2 MHz, respectively. Moreover, the reproduced passband modulation scheme provides a bit rate of up to 1.25 Mb/s with a communication range of 100 cm and a peak efficiency of 94%.