With the evolution of computing, consumer electronics, and mobile communication, end-user data requirements have been increasing exponentially in recent years. Visible light communication (VLC) employing light-emitting diodes (LEDs) for simultaneous illumination and data transmission can utilize license-free operation over hundreds of THz to deal with radio spectrum congestion problems. This thesis focuses on the VLC transceiver design with equalizations to compensate for the limited modulation bandwidth of optoelectronic devices, and discusses the modulation schemes for maximum bit efficiency.

In the first part, a cross-domain integrated system evaluation engine (ISEE) based on Matlab, ADS, and Cadence is introduced. The baseband modulation schemes including non-return-to-zero (NRZ), 4...[ Read more ]

With the evolution of computing, consumer electronics, and mobile communication, end-user data requirements have been increasing exponentially in recent years. Visible light communication (VLC) employing light-emitting diodes (LEDs) for simultaneous illumination and data transmission can utilize license-free operation over hundreds of THz to deal with radio spectrum congestion problems. This thesis focuses on the VLC transceiver design with equalizations to compensate for the limited modulation bandwidth of optoelectronic devices, and discusses the modulation schemes for maximum bit efficiency.

In the first part, a cross-domain integrated system evaluation engine (ISEE) based on Matlab, ADS, and Cadence is introduced. The baseband modulation schemes including non-return-to-zero (NRZ), 4-level pulse amplitude modulation (PAM-4), and direct-current offset OFDM (DCO-OFDM), and the performance measures including data rate, bit error rate, and transmission distance are designed in Matlab. The ISEE evaluates the transceiver circuits designed in ADS or Cadence, and compares the system performance of different modulation schemes under different signal-to-noise ratio and bandwidth constraints.

In the second part, an asymmetric differential cascode trans-impedance amplifier (TIA) employs a PMOS negative capacitor and NMOS negative gm for achieving a 2.8x bandwidth improvement. Using a photodiode with 1.8 pF parasitic capacitance, the proposed TIA achieves a trans-impedance gain of 75 dBΩ and a -3dB bandwidth of 2.3 GHz. It also attains a 0.21 uA_rms input-referred noise (IRN) current, which is 0.04 uA_rms lower than that of the symmetrical design. A VLC transceiver based on the TIA is further verified using the ISEE to evaluate the performance of different signaling and modulation schemes including NRZ, PAM-4, and DCO-OFDM. The results show that PAM4 with feed-forward equalization (FFE) achieves the highest data rate at 5 Gb/s over a 1.5 m distance. In addition, the 1.67x bit efficiency improvement brought by the proposed design is verified at a distance of 1.5 m.