The lpGBTIA, a 2.5 Gbps Radiation-Tolerant Optical Receiver using InGaAs photodetector

The Low Power GigaBit Transimpedance Amplifier (lpGBTIA) is the optical receiver amplifier in the lpGBT chipset. It is a highly sensitive transimpedance amplifier designed to operate at 2.56 Gbps. It is implemented in a commercial 65 nm CMOS process. The device has been designed for radiation tolerance and, in particular, to accommodate the radiation effects in photodiodes that manifest themselves as an increase of both their dark current and junction capacitance. The optical receiver consisting of the lpGBTIA connected to an InGaAs photodiode has been successfully tested and irradiation tests showed that the power penalty remains below 4 dBm for exposition to a very high neutron fluences of the order of 10 15 n/cm$^2$.