A laser driver for a four-channel parallel fibre optic transceiver operating up to 2.5 Gbit/s is designed using a 0.35 μm SiGe BiCMOS process. An 850 nm vertical cavity surface emitting laser diode array is used as a light source. The measurement was performed under the case temperature range 0-80°C at 3.1 to 3.5 V power supply variations. Using a gigabit Ethernet filter, a 45% eye mask margin has been achieved at -4 dBm average optical power and 7 dB extinction ratio at 40°C. The rise/fall time is less than 100 ps. The measured deterministic jitter is under 60 ps and the random jitter under 4 ps RMS.