CMOS multi-level signal transmitter for optical communication

A multi-level signal transmitter for optical communication was designed using the TSMC 0.18 /spl mu/m CMOS mix-signal process with up to 10Gbps data throughput. The system consists of a MOS current mode logic (MCML) encoder, a d-flip-flop (DFF), a multi-level generator, and a laser driver. With an input speed of 2.5Gbps and a 1.8V power supply, the eye opening of each level has a height > 7mA and a width > 102ps in the 4-level system, a height > 3mA and a width > 90.14ps in the 8-level system, and a height > 1.5mA and a width > 87ps in the 16-level system with a 10% variance. A new multi-level modulation scheme without employing multiplexing (MUX) in a single channel can be realized on chip with less implementation complexity to improve the spectral efficiency.