Development of an ADC Radiation Tolerance Characterization System for the Upgrade of the ATLAS LAr Calorimeter

Abstract: ATLAS LAr calorimeter will perform its Phase-I upgrade during the long shut down (LS2) in 2018, a new LAr Trigger Digitizer Board (LTDB) will be designed and installed. Several commercial-off-the-shelf (COTS) multichannel high-speed ADCs have been selected as possible backups of the radiation tolerant ADC ASICs for LTDB. In order to evaluate the radiation tolerance of these back up commercial ADCs, we developed an ADC radiation tolerance characterization system, which includes the ADC boards, data acquisition (DAQ) board, signal generator, external power supplies and a host computer. The ADC board is custom designed for different ADCs, which has ADC driver and clock distribution circuits integrated on board. The Xilinx ZC706 FPGA development board is used as DAQ board. The data from ADC are routed to the FPGA through the FMC (FPGA Mezzanine Card) connector, de-serialized and monitored by the FPGA, and then transmitted to the host computer through the Gigabit Ethernet. A software program has been developed with Python, and all the commands are sent to the DAQ board through Gigabit Ethernet by this program. Two ADC boards have been designed for the TI ADS52J90 and ADI AD9249 respectively. TID test of both ADCs have been performed at BNL, and SEE test for ADS52J90 has been performed at Massachusetts General Hospital (MGH). Test results have been analyzed and presented. The test results demonstrate that our test system is very versatile, and working well for the radiation tolerance characterization of commercial multi-channel high-speed ADC for the upgrade of the ATLAS LAr calorimeter. It is applicable to other collider physics experiments where radiation tolerance is required as well.