On the development of the final optical multiplexer board prototype for the TileCal experiment V. González Dep. of Electronic Engineering University of Valencia, Spain

Outline Introduction Previous work OMB 6U Final prototype OMB 9U Present status

Introduction RODs interface LVL1 and LVL2 at each detector –Some preprocessing available if needed For TileCal, radiation issues changed front end connection to RODs –Two fibers with same data output each FrontEnd board –Need to select the fiber with good data in case of errors (OMB aka PreROD)

Previous work OMB 6U Specifications –VME 6U Board format –2 input channels (4 input 640 Mbit/s –2 output channels (2 output fibers) –Digital data analysis (CRC computation) –Trigger and Busy inputs

Previous work OMB 6U Functionality –Error detection (multiplexing) –Data injection Preconfigured event (counter) Configurable event loadable through VME –Different trigger options External (NIM or LVTTL) Internal. Variable frequency –Single –Loop –Non-stop

Previous work OMB 6U Designed with Cadence PSD 15.0 and Altera Quartus II for FPGA programs Technical details –2 Cyclone EP1C12 and 1 ACEX EP1K100 FPGAs –12 copper layers, 35 μm thick –> 2000 routes 0.15 mm width –> 2000 vias 0.2 mm –SMD components widely used

Previous work OMB 6U TEST at Valencia LAB –Firmware adjustment –Integration with ROD motherboard –Development of control software (XTestROD) TEST at CERN (USA15) –During commissioning –Integration with 8 TileCal ROD –Used now for ROD production tasks

Final prototype OMB 9U Same basic functionality –CRC checking –Data injection –40 MHz clock Differences –8 channels 16 input fibers 8 output fibers –TTCrx –Mezzanine connectors: more processing power?

Final prototype OMB 9U Technical details –9U VME slave board –Dual optoelectronic transmitter/receiver (Stratos) –GLINK chips 8 HDMP-1032: transmitter 16 HDMP-1034: receiver –8 Cyclone EP1C12 (CRC FPGA) One for each channel (2 input fibers and 1 output fiber) –1 Cyclone EP1C20 (VME FPGA) Changed from ACEX in 6U version for more logic resources Includes TTCrx control firmware

Final prototype OMB 9U

PCB details –Input/output signals designed for operation at 80 MHz –10 copper layers Signal layers between power/gnd planes Adjacent layers routed orthogonally for minimum coupling

Final prototype OMB 9U Signal integrity issues –Big area, not too much populated Long distance traces (high coupling) Clock distribution JTAG chain distribution VME-CRC FPGA serial bus –Different voltage supplies +3.3 Volt for FPGA I/O and some logic +1.5 Volt for FPGA cores (island) +5 Volt for logic +12 Volt for NIM/TTL conversion (ext. trigger input)

Final prototype OMB 9U Example of SI analysis: VME to CRC serial BUS –Connected between the VME FPGA and all CRC FPGAs –For control, communication, configuration, etc. –4 lines: CLK, DATA0, DATA1, DATA2, DATA3 –Frequency of operation 40 MHz

Final prototype OMB 9U First attempt –Manual placement and routing of bus lines –Keep stubs short –Keep same routing layer as much as possible –R, RC termination Problem –Characteristic impedance change at T junction –Reflections at first FPGA creates InterSymbol Interference (ISI)

Final prototype OMB 9U PostLayout simulation

Final prototype OMB 9U Second attempt –Manual placement and routing of bus lines –Keep stubs short –Keep same routing layer as much as possible Problem –Reflections with different termination schemes

Final prototype OMB 9U PostLayout simulation

Final prototype OMB 9U Final attempt –Manual placement and routing of bus lines –Keep stubs short –Keep same routing layer as much as possible Solution –Resistive termination at both ends

Final prototype OMB 9U PostLayout simulation

Present status Stratos change connectors to be RoHS compliant –Need to test new connectors Board routing on the way –SI analysis still undergoing: JTAG chain, clock distribution and power distribution FPGA firmware adaptation

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