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Noise Susceptibility Studies / Magnetic Field Tests - Status & Plans of the Aachen Group

Noise Susceptibility Studies / Magnetic Field Tests - Status & Plans of the Aachen Group. Lutz Feld, Rüdiger Jussen, Waclaw Karpinski, Katja Klein , Jennifer Merz, Jan Sammet 1. Physikalisches Institut B, RWTH Aachen University. Tracker Upgrade Power WG Meeting June 4 th , 2009. Outline.

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Noise Susceptibility Studies / Magnetic Field Tests - Status & Plans of the Aachen Group

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  1. Noise Susceptibility Studies / Magnetic Field Tests - Status & Plans of the Aachen Group Lutz Feld, Rüdiger Jussen, Waclaw Karpinski, Katja Klein, Jennifer Merz, Jan Sammet 1. Physikalisches Institut B, RWTH Aachen University Tracker Upgrade Power WG Meeting June 4th, 2009

  2. Outline • Personal & funding • Noise susceptibility studies • Magnetic field test of DC-DC converters • Plans • Summary Status Report from Aachen

  3. Update on Personal • Lutz Feld: team leader • Waclaw Karpinski:electronics engineer • plus electronics workshop team • Katja Klein: Helmholtz Alliance fellow (4-years from April 08) • Two PhD students: • Jan Sammet • Rüdiger Jussen • Diploma student: • Jennifer Merz (Effect of powering schemes on the material budget) Status Report from Aachen

  4. Funding News • We have received from BMBF (= main German funding body for HE physics) for the next 3-year funding period,starting July 09: • invest money • 3 PhD positions for SLHC Status Report from Aachen

  5. Summary of Activities • Investigation of system aspects of novel powering schemes • PCB development & system tests  separate talk today by Jan Sammet • Noise susceptibility measurements • Noise injection into silicon strip modules  covered in this talk • Contribute to the development & characterization of magnetic field tolerant and radiation hard DC-DC buck converters, in coll. with CERN PH-ESE group • Magnetic field test  covered in this talk • Integration and test of CERN converters with CMS strip modules only short summary of plans today • Simulation of material budget of different powering schemes  final results ready, will be presented in the next meeting Status Report from Aachen

  6. Noise Susceptibility Studies • Goal: identify particularly critical bandwidth(s) for converter switching frequency • Bulk current injection (BCI) test-stand has been set up (Rüdiger Jussen) • A noise current of 70dBA (Ieff = 3.16mA) is injected into the power lines • Differential Mode (DM) and Common Mode (CM) on 2.5V and 1.25V Status Report from Aachen

  7. BCI Set-up Injection & current probe LISN Current probe in CM configuration Petal Frequency generator Power supplies Amplifier Spectrum analyzer Noise injection into one module (6.4) • Noise is injected into a single module • Frequency swept from 100kHz – 100MHz • Step width: 0.1MHz between 100kHz and 10MHz, 1.0MHz between 10MHz and 30MHz, 2.5MHz between 30MHz and 100MHz Status Report from Aachen

  8. Effects on Module Noise Status Report from Aachen

  9. Effects on Module Noise Mean noise of APV2 Noise of strip 512 • Edge strips much more sensitive due to their coupling to the bias ring • On-chip common mode subtraction is very efficient for most strips • More in back-up slides •  Concentrate on edge strips Status Report from Aachen

  10. Peak Mode • Peak at 6-8MHz, not at 1/(250ns) = 3.2MHz, as expected from shaping time • Higher susceptibility for differential mode and 1.25V = pre-amp reference voltage • Peak position independent of injected amplitude or module position Status Report from Aachen

  11. Peak vs. Deconvolution Mode Deconvolution mode Peak mode • Slight shift of peaks • Interpretation difficult Status Report from Aachen

  12. What about Higher Frequencies? Zoom • Cable resonances can be observed if cable length L = n/4 • Two open ends (LISN 50, module ~ 2)  L = /2 • Cable length varied between ~ 1.1m, 1.5m, 2.1m  f = 89.8MHz, 65.9MHz, 47.0MHz • Measurements above ~ 30MHz are not reliable • But no shift of peaks below 30MHz Status Report from Aachen

  13. Influence of Pre-amp Reference Voltage DM, 2.5V APV25 pre-amplifier V250 V125 strip bias ring VSS=GND [Mark Raymond] connected toGround connect toV125 • Edge strips are capacitively coupled to bias ring • Bias ring referenced to ground, pre-amp to 1.25V • Bias ring connected to 1.25V instead of ground Susceptibility decreases drastically Pre-amp should be referenced to ground [Hybrid] Status Report from Aachen

  14. BCI Summary • Results are ~ consistent with measurements of Fernando Arteche (2004) • Powerful method, but interpretation difficult (needs modelling) • Shorter measurement time needed for faster turnaround (now ~ 1d per curve) automation of measurement with LabView is foreseen (Rüdiger) • Will be useful to characterize susceptibility of SLHC devices (hybrids, modules, ...) F. Arteche, measurements with TEC petal in Aachen, 2004 (SLAC-PUB-11886, May 2006 ) Status Report from Aachen

  15. Magnet Test • DC-DC converters must function in ~ 4T magnetic field  no magnetic components • Tests with 7T NMR-magnet at Forschungszentrum Jülich, close to Aachen • Enpirion and CERN AMIS1 buck converters + LBNL charge pump tested (Rüdiger) • both versions with air-core and ferrite coils • 13 DC-DC converters tested in total (can show only examples here) Status Report from Aachen

  16. Magnet Test Set-up Scope with probes Handle being inserted into magnet Magnet PS Sourcemeter = Load Windows-PC running LabView B field Handle for probes 9m long BNC cables Status Report from Aachen

  17. Efficiency Measurement Value set in sourcemeter and monitored with current probe Regulated by converter Measured with PS Set and measured with PS Correction for cable losses • Note: the output voltage was not measured  this must be changed in the future! • Efficiency was measured inside and outside of magnet with same set-up • Measurement of other observables (ripple?) difficult due to long cables • what else should be measured? Status Report from Aachen

  18. Enpirion EQ5382D Buck Converter Enpirion with ferrite coil Vout = 1.25V • Severe efficiency loss with ferrite inductor • Efficiency change < 0.5% with air-core inductor Efficiency (7T) / Efficiency (0T) Enpirion with air-core toroid Vout = 1.25V Eff. (7T) / Eff. (0T) Status Report from Aachen

  19. AMIS1 Buck Converter w/ Air-Core Solenoid Efficiency (7T) / Efficiency (0T) • Efficiency changes by less than 5% with air-core inductor • Reason for larger deviations wrt Enpirion not clear, converter stability? • With ferrite inductor, PS went in over-current condition (back-up slides) Status Report from Aachen

  20. LBNL Charge Pump • No efficiency change for Vout = 2.5V • For Vout = 1.25V, converter was probably not in same “state“ (stability problems) Status Report from Aachen

  21. Magnet Test Summary • No surprises: • All converters with ferrite coils showed severe efficiency loss or over-current • All converters with air-core inductors, plus charge pumps, worked without significant efficiency loss • We know now how to do the measurements and what to improve • Measure output voltage • Test various coil orientations • Time needed for a measurement campaign: 2 days (but must be arranged) • Suggest to repeat test with CERN ASIC in IHP technology and improved set-up • maybe also with AMIS2? Status Report from Aachen

  22. Future Plans • System test with strip modules of • CERN buck converter PCB with discrete components (started) • CERN AMIS1 with Bristol PCB inductors (asap) • CERN AMIS2 buck converter ASIC (summer) • CERN IHP buck converter ASIC (autumn) • PCB development for integration of DC-DC converters into tracker structures • Automate and improve several existing test-stands (BCI, EMI, efficiency) • Set up EMI-scanner to investigate coupling mechanisms of radiated noise • Continue material budget studies • Develop specifications for buck converter • Get more practical experience with charge pumps Status Report from Aachen

  23. Summary & Conclusions • A bulk current injection test-bench for noise susceptibility studies has been set-up and first measurements have been performed • Various DC-DC converters have been tested in a 7T magnetic field • Both set-ups need some improvements, but seem to be useful for tests of future converter and module prototypes • Simulation of material budget for powering/cooling schemes finished, will be presented in the next meeting Status Report from Aachen

  24. Back-up Slides Status Report from Aachen

  25. The APV25 f = 1/(250nsec) = 3.2MHz Status Report from Aachen

  26. The APV25 1.25V 2.5V * * is connected to 2.5V since about 2000 Status Report from Aachen

  27. The APV25 1.25V 2.5V Status Report from Aachen

  28. On-Chip Common Mode Subtraction • 128 APV inverter stages powered from 2.5V via common resistor (historical reasons)  mean common mode (CM) of all 128 channels is effectively subtracted on-chip • Works fine for regular channels which see mean CM • CM appears on open channels which see less CM than regular channels • CM imperfectly subtracted for channels with increased noise, i.e. edge channels pre-amplifier inverter V250 R (external) V250 V125 vCM strip vIN+vCM vOUT = -vIN VSS Node is common to all 128 inverters in chip Status Report from Aachen

  29. Common Mode & Differential Mode Differential Mode (DM): Source Load Common Mode (CM): Source Load Status Report from Aachen

  30. AMIS1 Buck Converter w/ Ferrite Coil Status Report from Aachen

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