DC-DC Conversion Studies – Status Report from Aachen

DC-DC Conversion Studies – Status Report from Aachen

Tracker Upgrade Power WG MeetingFebruary 13th, 2009

Lutz Feld, Rüdiger Jussen, Waclaw Karpinski, Katja Klein, Jennifer Merz, Jan Sammet

1. Physikalisches Institut B, RWTH Aachen University

Personal

Katja Klein 2Status Report from Aachen

• Lutz Feld: team leader

• Waclaw Karpinski: electronics engineer– plus electronics workshop team

• Katja Klein: Helmholtz Alliance fellow (4-years from April 08)

• Jan Sammet: PhD student

• Two diploma students:– Rüdiger Jussen (DC-DC converter studies)

– Jennifer Merz (Analysis of the material budget)

Funding


• We have joined the SLHC-PP project of the EU FP-7 program (Work Package 8: Tracking detector power distribution)

• In Germany, next 3-year BMBF funding period starts in July 2009 Have applied for invest money and positions First feedback in May

Work Plan from Mid 2008


• Investigation of system aspects of novel powering schemes– DC-DC conversion

– Serial powering?

• Noise susceptibility measurements– Noise injection into silicon strip modules

– Noise injection into DC-DC converters

• Contribute to the development & characterization of magnetic field tolerant and radiation hard DC-DC buck converters, in coll. with CERN PH-ESE group– Duplicate CERN test-stand for converter noise characterization

– PCB development

– Magnetic field test

– Irradiation tests

• Simulation of material budget of different powering schemes








– PCB development




First round of system tests with comm. buck converters finished.

No concrete plans; concentrate on DC-DC conversion.

• Results summarized by Lutz in October meeting http://indico.cern.ch/getFile.py/access?contribId=0&resId=0&materialId=slides&confId=41790

System Test with DC-DC Converters


Noise of Enpirion converters can be controlled by combination of shielding and filtering (LDO).

--- No converter--- Converter--- Converter + 30m Alu shielding--- Converter + LDO--- Converter + LDO + 30m Alu shielding

• Studies with commercial buck converters documented in Jans thesis CMS TS-2009/003 “System Test Measurements with a DC-DC Conversion Powering Scheme for the CMS Tracker at SLHC”

http://indico.cern.ch/getFile.py/access?contribId=0&resId=0&materialId=slides&confId=41790








– PCB development




Not yet done, still planned.

Ongoing.

Noise Susceptibility Studies


• Goal: identify particularly critical bandwidth(s) for converter switching frequency

• Bulk current injection test-stand has been set up (Rüdiger)

Noise Susceptibility Studies


• Injection of I=70dBA (3mA) into power lines (2.5V, 1.25V, differential/common mode)

• Results not quite as expected; current interpretation: APV25 on-chip common mode subtraction is again hiding the real system response

Deconvolution mode;mean noise of one APV

Mean noise of one APV;zoom

Deconvolution mode;noise of strip 512

Noise of strip 512;zoom

Peak at around 6-8MHzseen for edge strips, but not in mean APV noise

2.5V, Diff. Mode 2.5V, Diff. Mode

Results will be presented at the next meeting.

?








– PCB development




Done.

Currently covered by CERN.

Done.

PCB for SWREG2 chip done; PCB development ongoing.

PCB Development


• Aim for compactness and low mass

• Study possibilities for efficient low mass shielding (e.g. Parylene-coating)

• Study and improve noise filtering

• First prototype being characterized

• New PCBs expected for April

• In addition: PCB with LTC3568 buck converter; switching frequency configurable up to 4MHz; in hands, to be tested

Enpirion EQ5382DLDO LTC3026

3cm

Magnet Test


• Tests performed with 7T NMR-magnet at Forschungszentrum Jülich, close to Aachen

• Enpirion converter, CERN SWREG2, LBNL charge pump tested both versions with air-core and ferrite coils

• Result: converters with air-core inductors and charge pump worked fine; converters with ferrite inductors stopped working or lost their efficiency

Uout = 2.5V

Details will be presented at the next meeting.








– PCB development




Presentation by Jennifer

Summary & Outlook


• Simulation studies are far advanced presentation today

• Magnet test done

• Noise injection into modules to be finished

• PCB development continues; focus on low mass, low noise, shielding

• System test measurements are restarting

• Development of test-stand to study systematically the coupling of noise from air-core inductors to the modules

• Feedback from funding agency needed for longer timescale planning!

Documents

DC-DC Conversion Studies – Status Report from Aachen