Based on a 0.13 μm SiGe BiCMOS process, a linear driver was designed. With the advantages of high speed and large swing, the driver supported to linearly drive Traveling-Wave Mach-Zehnder Modulator (TW-MZM) to meet the application requirements of 100 Gbit/s single channel in optical communication systems. The driver included Continuous Time Linear Equalization (CTLE), Variable Gain Amplifier (VGA) and the output stage optimized based on cascode structure. It achieved adjustable gain and avoided transistor breakdown caused by large output swing. Simulation results show that the -3 dB bandwidth of the driver is 43 GHz, and its gain is adjustable from 15 dB to 25 dB. Under 56 Gbaud NRZ/PAM4 signal input, eye diagrams are measured well. The differential output swing pp value is up to 4 V, the total power consumption of the driver is 1.02 W, and the occupied area is 0.33 mm2.