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Jitter and BER measurements on the CuOF prototype

Jitter and BER measurements on the CuOF prototype. G. Dellacasa, G. Mazza – INFN Torino CMS Muom Barrel Workshop CERN, February 25th, 2011. Outline. CuOF boards short description Test bench description Jitter measurements results BER results

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Jitter and BER measurements on the CuOF prototype

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  1. Jitter and BER measurements on the CuOF prototype G. Dellacasa, G. Mazza – INFN Torino CMS Muom Barrel Workshop CERN, February 25th, 2011

  2. Outline • CuOF boards short description • Test bench description • Jitter measurements results • BER results • Design of the Versatile Link prototype board: GBT13 Laser Driver (GBLD) jitter measurements results • Conclusions Dellacasa Giulio

  3. CuOF prototype • Proposal: to move ROS and TSC from UXC55 to USC55 • Needs to fabricate the optical transmitters (UXC55) and the optical receivers (USC55) • Cu to Optical Fiber (CuOF) prototype board has been developed at CIEMAT to evaluate the best candidates for the line equalizer and laser driver to use. TX hosts: • 2 line equalizer: LMH0024 and MAX3800 • 3 laser driver: MAX3643, MAX3646 and SY88216 • CuOF RX hosts Finisar FTLF8519F2 optical receiver • The 6 possible combinations in the TX board have been tested Dellacasa Giulio

  4. Stanford Research SRS-CG635: 2.05 GHz clock and PRBS data generator Agilent N5980A: 3.125 Gb/s BERT Agilent 16702B: 200MHz LSA / 300 MHz Pattern Gen. CuOF TX and RX Tektronix DPO 70604: 6GHz; 25 GS/s Test bench Dellacasa Giulio

  5. Instrumentation details • Agilent LSA /Pattern Generator: used for preliminary tests • PRBS data generation and data out checks • Not good enough for real tests (only 300 Mb/s generator and 200 MHz LSA). Also its jitter is not adequate: 105 ps rms random jitter @ 240 Mb/s • Tektronix 6 GHz oscilloscope: used for jitter analysis • SRS-CG635: used as PRBS data generator (fixed pattern 27-1, at any rate). Its jitter performances are very good: 1.95 ps rms @ 240Mb/s and 1.81 ps rms @ 480 Mb/s (random jitter) • Agilent N5980A: BER tester. Only most common serial communication standards are supported (so not our whished rates) Dellacasa Giulio

  6. CuOF TX and RX details • In order to connect the two boards to the instruments, home made adapters have been inserted (2-pin to SMA connectors). This of course can degrade quality of signals and it has to take into account in the final results • All the measurements (jitter and BER) have been taken at the end of the transmission channel (TX + fiber 40 cm + RX) Dellacasa Giulio

  7. Jitter measurements: 240 Mb/s PRBS: 27-1 Maxim and Micrel datasheet: MAX3643 -> up to 2.5 Gb/s MAX3646 -> up to 622 Mb/s SY88216 -> up to 2.5 Gb/s Dellacasa Giulio

  8. Jitter measurements: 480 Mb/s PRBS: 27-1 Maxim and Micrel datasheet: MAX3643 -> up to 2.5 Gb/s MAX3646 -> up to 622 Mb/s SY88216 -> up to 2.5 Gb/s Dellacasa Giulio

  9. LMH0024 + MAX3643 480 Mb/s Dellacasa Giulio

  10. LMH0024 + SY88216 480 Mb/s • Asymmetry in rising / falling edges (falling edge is faster) • Jitter is visible Dellacasa Giulio

  11. MAX3800 + MAX3646 480 Mb/s • Jitter is visible Dellacasa Giulio

  12. LMH0024 + MAX3646 480 Mb/s Dellacasa Giulio

  13. MAX3800 + SY88216 480 Mb/s • Asymmetry in rising / falling edges (falling edge is faster) • Jitter is visible Dellacasa Giulio

  14. MAX3800 + MAX3643 480 Mb/s Dellacasa Giulio

  15. BER • The Agilent BER tester supports only the most common serial communication standards • The BER has been measured using the OC-12 standard. Its rate is 622.08 Mb/s (more than our needs!) • Data sequence: PRBS 27-1 • Each channel tested for one hour • For all the 6 combinations in the TX board (equalizer + laser driver) no errors where observed (also with LMH0024 which has declared data rates 125 Mb/s to 540 Mb/s) • BER < 10-11 • The Agilent BER tester has an optimum data recovery circuit. To see if these results will be confirmed in the final system with ROS and TSC receivers Dellacasa Giulio

  16. Versatile Link GBLD Dellacasa Giulio

  17. Jitter measurements @ 5Gb/s Ipre=0 TJ= 32.90 ps RJ=0.62 ps DDJ=24.78 ps DCD =3.08 ps ISI=22.25 ps Ipre=3.6 mA TJ= 22.39 ps RJ=0.61 ps DDJ=14.56 ps DCD =2.31 ps ISI=11.61 ps Dellacasa Giulio

  18. Conclusions • At the required data rates (240 Mb/s and 480 Mb/s) all the combinatorial of the components present on the CuOF prototype board behaved successfully • Jitter behaviour seems to be dominated by the laser drivers. Best performance is given by the MAX3643 (Maxim) and worst performance by the SY88216 (Micrel). The latter is to be understood because has an unexpected jitter’s value for its nominal characteristics (2.5 Gb/s). A second CuOF board would be useful for comparison • BER seems to be very good (<10-11) at these data rates • Next steps: • to study the CuOF board within the real system in order to evaluate the impact of other components (data from Minicrates, cables and fibers length, TSC and ROS receivers etc.) • design and test of the Versatile Link prototype board with both GBLD and commercial laser drivers • define (hopefully before the end of 2011) the required interfaces and study of the system integration (voltage regulators? DCS? Programmable options? Mechanical integration? Etc.. etc..) Dellacasa Giulio

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