Bertalan Eged*, Csaba Soós, Zoltán Varga, Technical University of Budapest, Department of Microwave Telecommunications, High-speed Technology Team
Jozsef Molnár, András Fenyvesi, Gábor Dajko, Institute of Nuclear Research of the Hungarian Academi of Sciences

!!
High-speed (GB/s) optical links are widely used in the DAQ systems of LHC experiments. One of them is the Detector Data Link (DDL) which was developed for special requirements of LHC ALICE detector. The DDL consists of three main parts Source Interface Unit (SIU) Destination Interface Unit (DIU) and Read Out Receiver Card (RORC). The SIU unit will be placed inside the detector so it should be radiation tolerant. The main components of SIU card are the logic core chip with configuration prom, electrical transceiver, and optical transceiver. The total dose over 10 years at ITS detector is 40krad and the neutron fluences are 5*10e11n/cm2. The SIU will not be connected directly to Pixel detector where the radiation level is higher. Special test setup was developed using radiation tolerant components for realizing a digital interface to the radiation environment. With this test setup we are able to send test patterns to radiation environment and receiving the results in the control room.
The logic core is based on Altera FPGA technology at the prototypes of DDL SIU and DIU. First measurements was done with SRAM based FPGA with 0.35um technology and its configuration EEPROM. The measurements under radiation focused on the delay variation in core logic and I/O cells, setup and hold time degradation of logic gates and operation of high complexity logic subsystems including state machines, encoders/decoders, CRC circuits. However some manufacturer offer radiation tolerant AISIC processes the commercial FPGA circuits using deep submicron technology can be used in low level radiation environment.
The next main components of the serial links is the serialiser-deserialiser (SERDES) chip. In this components the parallel data is transferred to a gigabit-rate serial bitflow and some coding, link initialization, link control and error detection is done. The available chips have got serial PECL I/O which is enable to use them in copper based direct connections, but using optical transceivers the useable length of the link can be increased. The ALICE DDL based on the wide spread Fibre-channel technology so lot of electrical transceiver can be find in the market. Our primary goal was receiving basic information about the radiation hardness of these components. The measurements were done with measuring the bit error rate of the link under loop-back condition with different test patterns. The loop-back was realized with the internal switch of the chip.
The third main component is the optical transceiver. Due to the strong area and power limitation of DDL SIU card the small form factor optical transceiver (SSFOT) with single 3.3V supply is the only candidate for this task. In the last year lot of company announced his SSFOT products. The main goal was receiving basic information about radiation hardness of these COTS elements. The measurements were done by measuring BER in loopbacked link.
Our measurement facilities include gamma photons and on-line neutron test. High total dose with different dose rates and annealing effect is measured. 

!!
High-speed (GB/s) optical links are widely used in LHC experiments. One of them is the Detector Data Link (DDL) which was developed for special requirements of LHC ALICE detector. The DDL consists of three main parts Source Interface Unit (SIU) Destination Interface Unit (DIU) and Read Out Receiver Card (RORC). The SIU unit will be placed inside the detector so it should be radiation tolerant. The main components of SIU card are the logic core chip with configuration prom, electrical transceiver, and optical transceiver. The special measurement test setup was developed and the on-line radiation hardness measurements of these components were done with gamma photons and neutron beam with high total dose and different dose rates. In this paper we would like to discuss our results about the measurements of these essential link components.
!!