125Mbit/s×3 Transmitter for Short-Distance Optical Link Using Low-Cost RGB-LED

A simple low-cost transmitter using low power RGB-type white LED is presented in this article. This type of white LED is widely used for illumination and communication applications. However, the low modulation bandwidth of RGB-LED, which is a few tens of MHz, limits the data rate of a transmission link. By applying a current-shaping-circuit (CSC), we can significantly improve the OOK-NRZ modulation speed of an AlGaInP red LED by a factor of 5. In this article, three color LEDs are separately modulated for data transmission. A data rate of 125Mbit/s×3 has been demonstrated with the aim to comply with Fast Ethernet (100Mbit/s) protocol.