A fully integrated burst-mode upstream transmitter chip for gigabit-class passive optical network applications is implemented in 0.18µm CMOS technology. In order to control consecutive burst data, the transmitter proposed in this paper uses a reset mechanism with TX_enable as a burst envelope signal. The feedback from the monitoring photodiode (MPD) is separated by two independent paths for temperature compensation. The chip tested with chip-on-board configuration shows an average power of 2dBm with extinction ratio of above 12dB under 1.25Gb/s burstmode operation. Based on the measurement, this work complies with the GPON ITU-T Recommendation G.984.2.