Implementation of the Equalization Circuits for High Bandwidth Visible Light Communications Using Phosphorescent White LED

In this paper, a commercial phosphorescent white light-emitting diode (WLED) visible light communication (VLC) system with an equalization circuit to achieve the high modulation bandwidth was designed and demonstrated. An analytical method to examine the performance of the equalizer was carried out using a general circuit-simulator, PSpice. The equalization circuit was composed of two passive filters with resisters and a capacitor and an active filter with an op-amp. Utilizing our post-equalization technology, the ∼3.5 MHz bandwidth of phosphor WLED could be extended to ∼25 MHz without using an optical blue-filter. In this VLC system with a single round-type WLED and a single PIN photo-diode, ASK data transmission up to 35 Mbps at a 1m free space distance was obtained. The resulting bit-error-rate was 7.6×10 -4 , which is less than the for- ward error correction (FEC) limit of 3.8×10 -3 .