Transcript Folie 1 - Server der Fachgruppe Physik der RWTH Aachen
Tracker Power System – Requirements and Studies
Katja Klein
RWTH Aachen University
CMS Upgrade Workshop May 14th, 2009
https://twiki.cern.ch/twiki/bin/view/CMS/SLHCTrackerPower [email protected]
Outline
•
Introduction & requirements
•
Ongoing activities
•
Open questions
•
Next steps
•
Summary & conclusions
Katja Klein Tracker Power System 2
Motivation
• Increased granularity & functionality increase of power consumption • Lower operation voltage larger currents for same power consumption • Services must be re-used (P ~ I 2 ) • Decrease of material budget highly desirable
Novel powering scheme inevitable for the tracker (strips & pixels)
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Powering Schemes
Two powering schemes are widely discussed in the SLHC community:
Serial Powering
and
Powering via DC-DC converters Power Task Force recommendation
(Jan. 09, chair P. Sharp): “The ‘Task Force’ recommends that the
baseline powering system
for an upgraded CMS Tracking system
should be based on DC-DC conversion
, with
Serial Powering maintained as a back-up solution
reverting to the back-up solution at a later date.” . [...] It is important that design decisions taken during this process do not preclude Converter
C
converts a “high“ DC input voltage to voltage needed by detector D (V 0 ) Katja Klein Tracker Power System
Conversion ratio r = V 0
/ V
Lower input currents and
in
power losses: P drop = R cab I 0 2 r 2
< 1
4
Buck Converters
Inductor-based converters provide large currents and are very efficient - the
buck converter
is often studied as the simplest inductor-based variant Switching noise Ferrites saturate for B > ~2T air-core inductor needed bulky radiates noise V in 12V HV-tolerant semi-conductor technology needed radiation-hardness
Schematic scheme of a buck converter (feedback control loop not shown)
Katja Klein Tracker Power System Efficiency Material budget Space constraints 5
“Charge Pump“ = Switched Capacitors
In simple step-down layout: capacitors charged in series and discharged in parallel I out = n I in , with n = number of parallel capacitors Capacitors are external space, mass (but less than coil!) Katja Klein Many switches noise, losses Must be rad.-hard and tolerate V in Tracker Power System Efficiency No regulation (costs efficiency) Lowish currents 6
Strip Power System Requirements
• Compatibility with both trigger and tracking layers • A large conversion ratio (depends on tracker power consumption) • Adequate efficiency (depends on r, but roughly > 80%) • Provision of all necessary low voltages: V ana = 1.2V, V dig ~ 0.9V, V opto = 2.5V
• Provision of ~ 50mA per chip, i.e. ~ 1A per module for outer tracking layers • Provision of up to several Amps for trigger modules (depends on module variant) • Provision of sufficient bias voltage with sufficient granularity • Must not compromise the noise behaviour of the system (depends on FE-PSRR) • Compatibility with existing Low Impedance cables Low voltage: V < 30V, I < 20A; high voltage: V < 600V, I < 0.5A
• Must respect heat tolerance of cable channels • Contribution to material budget as low as possible • Must be small enough to fit (details depend on integration) • Save operation & easy start-up of thousands of modules • Include proper grounding and shielding strategy Katja Klein Tracker Power System 7
Power WG Activities
Topic / Scheme DC-DC conversion (baseline solution)
Serial powering (back-up solution) Implementation Katja Klein
Electronics development Non-isolated inductor-based:
CERN (technology, ASIC development, simulation); Aachen (PCB); Bristol (air-core coil)
System tests
Aachen (strips)
Transformer-based:
Bristol
Charge pump:
PSI (pixels); CERN (strips) Fermilab, Iowa, Mississippi (pixels) Piezo-electric transformer: (Fermilab) Fermilab, Iowa, Mississippi (pixels); Rochester? (strips) Karlsruhe (Powering via cooling pipes): on hold Power supplies, cables: not covered Tracker Power System
Material budget
Aachen Aachen 8
Phase-1: Power to the Pixels
•
Phase-1 pixel upgrade: 4 barrel layers and 3 end cap disks
FPIX power system layed out for 3 disks, no problem BPIX: 1612W 2919W (for L = 2 10 34 cm -2 s -1 ) cannot be supplied by current power supplies •
How to power this BPIX detector? Options being worked out by PSI
1. Modify & use existing CAEN power supplies (A4603) Status: modified PS in hands, to be tested 2. Use switched-capacitor DC DC converters (“
charge pump
“) a. Both for analog & digital power, conversion ratio 1:2 V ana = 1.7V, V dig = 2.5V device in HV-tolerant semiconductor process b. Only for analog power, conversion ratio 1:2 c. Derive V ana from V dig with 2:3 converter (less cables and connectors); in combination with modified PSs
Evaluation of options is ongoing, no conclusion yet
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On-Chip Charge Pump for Pixels
• Prototype by PSI (`08) • Conversion ratio 1:2 Charging phi 1 • I out = 24mA (1 ROC) • 0.25 m IBM CMOS • Ext. capacitors (10-100nF) V IN C1 phi 2 phi 1 C2 V OUT phi 2 • Test of noise behaviour with ROC to be done • Future options: version for 1 module (16 ROCs); ratio 2:3 V IN Discharging C1 phi 1 phi 2 phi 1 phi 2 C2 GND cap cap+ VDD del SW1 SW2SW3 Vout clk GND Katja Klein f [MHz] 10 20 40 P_SC 2 % 4 % 8 % P_Ri 14 % 15 % 18 % Pout 84 % 81 % 74 % Tracker Power System
Output voltage ripple
(f=4MHz, C=10nF) 5 mV/div V OUT 10
Pixel Power Distribution Studies
• Fermilab, Iowa, Mississippi •
Power distribution studies with pixel ROC (PSI46)
(Commercial) inductor-based converters with various PCB-embedded inductors, switched-capacitor regulators, Serial Powering Interface Chip (developed at Fermilab) •
CAPTAN DAQ system with daughter boards
for DC-DC conversion (ready) & Serial Powering flexible, powerful DAQ used during integration, can read out 480 ROCs • Measurements have just started Katja Klein Tracker Power System 11
Development of Converter ASICs
• • CERN electronics group, F. Faccio et al.
Buck controller ASIC in HV compatible AMIS I3T80 technology
(0.35
m CMOS) First prototype “AMIS1“ (summer 2008): working, but large switching losses Second improved prototype “AMIS2“ submitted, expected back in May 09 Semiconductor technology is not sufficiently radiation hard Nevertheless the AMIS2 will be tested within CMS (RWTH Aachen)
AMIS2
V in V out = 3.3 – 12V = 1.2, 1.8, 2.5, 3.0, 5.0V
f I out s < 3A = 400kHz – 3MHz Katja Klein Tracker Power System 12
Development of Converter ASICs
•
Identification of a sufficiently radiation-hard technology is crucial!
•
New semi-cond. technology: IHP (Frankfurt/Oder) SiGe BiCMOS (SGB25VD)
Irradiation tests of single LDMOS transistors (N and P) X-rays up to 350Mrad TID, protons (24GeV) up to 10 16 p/cm 2 Sufficienctly rad-hard for r > 20cm •
Buck ASIC including all main features submitted by CERN to IHP last week
expected back in ~ August •
More irradiations planned by CERN electronics group
(May/June): Various generations of IHP LDMOS transistors AMS 180nm LDMOS transistors •
Development of r = ½ charge pump in 130nm
(CERN + external student) I = 60mA; developed for Atlas, but could also be used in CMS readout chips Katja Klein Tracker Power System 13
Strip Tracker System Tests
•
Commercial buck converters used to systematically investigate effects on CMS FE-electronics
( Enpirion EN5382D: f s = 4MHz, V in < 7V) (Aachen) • Aspects studied: ferrite/air-core inductor, solenoid/toroid, Low DropOut reg., shielding
Current FE-electronics is sensitive to conductive & radiated converter noise
Improve PCB layout, develop efficient filtering and low mass shielding (ongoing, report in June meeting)
--- No converter --- Toroid converter --- Toroid converter + 30
m shield --- Toroid converter + LDO --- T. converter + LDO + 30
m shield
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Simulation of Strip Material Budget
• Reduction of material is one of the main motivations for novel powering schemes •
Simulation of the effect of powering schemes on the MB in CMSSW (Aachen) Total MB of: TEC modules TEC Converters TEC electronics & cables: - 30.0% Original TEC TEC with buck converters r = 1/8
• Many options/layouts have been studied (position, 1-step/2-step, shielding, ...)
Typical gain: ~20-30% for electronics/cables, ~5-7% for total MB
( Caveat: gain in motherboards is not only due to decreased current) Katja Klein Tracker Power System 15
Tasks / Open Questions & Next Steps: Pixels
•
Phase-1
How to power the pixel barrel detector during phase-1?
Is a switched-capacitor converter needed?
Various options being evaluated (PSI, 2009)
Charge pump development has started (PSI)
•
Phase-2
Are additional buck-like converters on service cylinder needed?
What is their effect on the pixel electronics?
Investigation of powering schemes on ROC (US, 2009/10)
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Tasks / Open Questions & Next Steps: Strips
•
Overall system layout must be defined
, in particular conversion ratio (depends on tracker power consumption) 1-step vs. 2-step scheme (depends e.g. on conversion ratio) # of converters/module (V ana , V dig ) integration onto module or motherboards (space, EMI, practicability, etc.) position of converter (close to module, or higher radii) bias voltage delivery (problematic, if > 600V are needed) integration of GBT components (2-3W, some parts need 2.5V) •
Specifications for ASIC & PCB
, driven by tracker needs output voltage & current, conversion ratio, switching frequency, tolerable noise level, minimal efficiency, tolerable dimensions etc.
Intense discussion over next couple of months, taking into account the recent layout developments/options
Try to narrow down powering options and develop a consistent scheme until autumn, to streamline powering R&D and guide other WGs
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Tasks / Open Questions & Next Steps: Strips
•
Interplay with readout ASIC(s)
PS rejection ratio, additional circuitry (regulators, charge pump)?
To be understood/decided together w/ FE designers; discussion has started
•
Cables
(not covered) •
Power supplies
(not covered) •
Performance of converter ASIC
(efficiency, optimal layout (buck?) etc.)
Development of custom buck converter prototypes
(CERN, 2009/2010) •
Semiconductor technology
Irradiation of transistors from IHP and AMS
(CERN, until autumn 2009) •
Noise effects on CMS tracker structures
System tests with converter prototypes
(Aachen, 2009/2010)
System tests with SLHC readout chips, hybrids, modules
(Aachen, 2010 - ?) •
Integration of DC-DC converters into tracker system
Developm. & optimization of PCB + inductor
(Aachen, CERN, Bristol, 2009/10)
Grounding & shielding, system design
(> 2010, needs rod prototypes) Katja Klein Tracker Power System 18
Summary & Conclusions
• HV-tolerant rad-hard process identified important step forward • Development of buck converter ASICs progressing well • Development of switched-capacitor chips started at PSI and CERN • Understanding of noise issues progressing at several institutes • Discussions during next couple of months should lead to a strip powering scheme that obeys all boundary conditions and is technically feasible • Iterate and converge towards Technical Proposals Katja Klein Tracker Power System 19
Katja Klein
Back-up Slides
Tracker Power System 20
R&D Proposals relevant for Power WG
07.01: R&D on Novel Powering Schemes for the SLHC CMS Tracker ; by RWTH Aachen (contact person: Lutz Feld), submitted in October 2007; status: approved 07.08: R&D in preparation for an upgrade of CMS for the Super-LHC by UK groups ; by University of Bristol, Brunel University, Imperial College London, Rutherford Appleton Laboratory (contact person: Geoff Hall), submitted in October 2007; status: approved 08.02: An R&D project to develop materials, technologies and simulations for silicon sensor modules at intermediate to large radii of a new CMS tracker for SLHC ; by University of Hamburg, Karlsruhe University, Louvain, HEPHY Vienna, Vilnius University (contact person: Doris Eckstein), submitted in March 2008; status: approved 08.04: Power Distribution System Studies for the CMS Tracker ; by Fermilab, University of Iowa, University of Mississippi (contact person: Simon Kwan), submitted in June 2008; status: approved Katja Klein Tracker Power System 21
Open Tasks
•
Cables
Understand consistency of LICs with new powering scheme Looks ok except for bias voltage Understand how to integrate LICs into new scheme Cables from PP1 to detector need replacement •
Power supplies
Very likely power supplies need to be exchanged Develop specs, identify and interact with company, test etc.
• Need to identify groups willing to take these responsibilities Katja Klein Tracker Power System 22