  In this paper, we present the design and test results of LOCx2, a transmitter
ASIC for the ATLAS Liquid Argon Calorimeter trigger upgrade. LOCx2 consists of
two channels and each channel encodes ADC data with an overhead of 14.3% and
transmits serial data at 5.12 Gbps with a latency of less than 27.2 ns. LOCx2
is fabricated with a commercial 0.25-um Silicon-on-Sapphire CMOS technology and
is packaged in a 100-pin QFN package. The power consumption of LOCx2 is about
843 mW.
