nsqp QA

I was responsible for designing and operating the opto-board quality assurance test set up for the next service quarter panel upgrade to the atlas pixel detector at CERN. For the hardware I chose a modular design that could be reused with other flavours of opto-boards not just those of the current production run.

The test system included:

  • 16 channel bit error rate tester(BERT) capable of running a 40, 80 and 160 Mbs with LVDS electrical output and fiber optic return
  • 8 channel BERT with recovered clock error testing running at 40 Mbs, Fiber optic output and LVDS electrical return
  • 8 channel analogue to digital converter (ADC) for measuring electrical parameters and setting bias currents and voltages
  • 2 channel digital to analogue converter (DAC) for setting bias currents
  • 2 switching power supplies to reduce the number of external supply voltages needed

The entire system was built around an Opal Kelly XEM-6002 module with a Sparten-6 on it. Using this module allowed for rapid development, that is, all assembly could be done in house and it also handled communications between the PC and the test system.

The firmware for the Sparten-6 was written in VHDL using Xillinx ISE and it implemented:

  • 24 BETRs
  • All had the option of a using a pseudo random bit stream (PRBS) generator or pattern buffer
  • All had option of bi-phase mark encoding
  • Eight had a recovered clock error detector
  • Serial interface for communicating with peripheral chips

The software for data collection was written in lab view and was responsible for running the entier opto-board Q\A with minimal human intervention. This included:

  • Measured optical power at +50C, 10C and -10C
  • Run bit error rate test for an hour at two different optical powers going into the receiver
  • Characterize the return electrical signal from the fiber optic receiver on the opto-board. This included rise time, fall time, amplitude and jitter
  • Measure Electrical supply current, Leakage current and set bias voltages

All in all the nsqp opto-board Q\A test system was a fairly compact and self contained test set up which required a minimal amount of external support hardware when compared to previous designs.

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