  We have been developing a serializer application-specific integrated circuit
(ASIC) based on a commercial 0.25-{\mu}m silicon-on-sapphire (SOS) CMOS
technology for the ATLAS liquid argon calorimeter front-end electronics
upgrade. The first prototype, a 5 Gbps 16:1 serializer has been designed,
fabricated, and tested in lab environment and in a 200 MeV proton beam. The
test results indicate that the first prototype meets the design goals. The
second prototype, a double-lane, 8 Gbps per lane serializer is under
development. The post-layout simulation indicates that 8 Gbps is achievable. In
this paper we present the design and the test results of the first prototype
and the design and status of the second prototype.
