8-Gbps-per-channel radiation-tolerant VCSEL drivers for the LHC detector upgrade

We present ASIC designs of VCSEL drivers for a single VCSEL (LOCld1), two individual VCSELs (LOCld2) and a four-channel VCSEL array (LOCld4). This work is for new detector readout systems needed in the Large Hadron Collider upgrade program. All ASICs are fabricated in a commercial 0.25-μ m Silicon-on-Sapphire CMOS technology. LOCld1 and LOCld2 have passed the 8-Gbps and 10-Gbps eye mask tests. Operating at 8 Gbps data rate, the measured total jitter of LOCld1 and LOCld2 is less than 30 ps, and the power comsuption is about 200 mW per channel with 6-mA bias current and 6.4-mA modulation current. The radiation tolerance of LOCld1 has been qualified with x-ray and high-energy neutron beam test.