  We fabricated a readout ASIC with the fully depleted silicon-on-insulator
(FD-SOI) technology for the pair-monitor. The pair-monitor is a silicon pixel
device that measures the beam profile of the international linear collider. It
utilizes the directional distribution of a large number of electron-positron
pairs created by collision of bunches, and is required to tolerate radiation
dose of about a few Mrad/year. The irradiation might cause the buried oxide
layer of SOI to accumulate charges which interfere with intended functions. We
thus performed extensive irradiation tests on the prototype ASIC, and the
results are described in this paper.
