The GBTIA, a 5 Gbit/s Radiation-Hard Optical Receiver for the SLHC Upgrades

The GigaBit Transceiver (GBT) is a high-speed optical transmission system currently under development for HEP applications. This system will implement bi-directional optical links to be used in the radiation environment of the Super LHC. The GigaBit Transimpedance Amplifier (GBTIA) is the front-end optical receiver of the GBT chip set. This paper presents the GBTIA, a 5 Gbit/s, fully differential, and highly sensitive optical receiver designed and implemented in a commercial 0.13 μm CMOS process. When connected to a PIN-diode, the GBTIA displays a sensitivity better than −19 dBm for a BER of 10−12. The differential output across an external 50 Ω load remains constant at 400 mVpp even for signals near the sensitivity limit. The chip achieves an overall transimpedance gain of 20 kΩ with a measured bandwidth of 4 GHz. The total power consumption of the chip is less than 120 mW and the chip die size is 0.75 mm x 1.25 mm. Irradiation testing of the chip shows no performance degradation after a dose rate of 200 Mrad.