Opto-electronic receiver system with post-equalization for visible light communications

Abstract

In this work, A significant increase in the data rate is achieved by designing an opto-electronic receiver for the visible light communication system. LEDs used at the transmitter side in the visible light communication system do not allow to transmit high data rates due to limited bandwidth. With the help of an equalizer, the data rate to be transmitted through LED can be increased. The designed opto-electronic receiver includes photodiode, trans-impedance amplifier (TIA), and equalizer blocks. First, the frequency response of the existing LED is extracted and its bandwidth is measured to be around 700 kHz. After obtaining a clear eye opening by transmitting a data at 1 Mbit/s, it is observed that the signal at the receiver side is impaired due to the intersymbol interference when the data rate is 50 Mbit/s. In the established setup, a data rate of 50 Mbit/s is achieved by using the same LED and the signal is properly received at the output of equalizer. Last, the bit error rate is obtained for higher data rates from 50 Mbit/s to 120 Mbit/s. By using only equalizer, a bit error rate of 10 -2 is achieved for the data rate of 90 Mbit/s by using LED with the bandwidth of 700 KHz.