A silicon-based microring modulator and a narrow-band optical Gaussian filter were employed to generate optical duobinary at 10 Gbit/s. Performance of the optical duobinary signal was analyzed in terms of laser linewidth, laser operating wavelength, fiber length, and filter bandwidth using Optisystem and Matlab. Simulation results show the optical duobinary signal is sensitive to laser linewidth and wavelength. At the BER of 10－9, the maximum transmission distance of the optical duobinary format can be up to 60 km with the optimal Gaussian filter bandwidth of 8 GHz.