Design Overview

The entire block diagram of the project is shown below.

The area located in the box is what is created on the chip.  The bottom portion of the chip (DRV and BUF) is the circuitry used to drive the transmission LED.  The circuitry on the top portion (TIA and CMP) is the transimpedance amplifier and comparator used in receiving the signal from the LED.  

The components off chip (outside the box) include the LEDs, potentiometers to adjust reference voltages/currents, and the connections to the FPGA.