Design and Implementation of a Pre-Equalizer for Visible Light Communication

The performance of a visible light communication (VLC) system is largely limited by the transmitter bandwidth. In a low-complexity VLC setup, the major bottleneck in data trans-mission throughput is due to the slow 3-dB bandwidth of the white phosphorescent LEDs. This paper presents the implementation of an analog passive pre-equalizer circuit to improve the transmitter bandwidth in a VLC system. The proposed design incorporates a cascaded constant-resonance amplitude equalizer. The proposed pre-equalizer circuit can improve the 3-dB bandwidth of the white LED from 5.5 MHz to 20 MHz. The increase in bandwidth corresponds to improvement in data transmission throughput from 22 Mbps to 51 Mbps using PAM-2 modulation.