Tracker Power System – Requirements and Studies CMS Upgrade Workshop May 14th, 2009 Katja Klein RWTH Aachen University

Outline Katja Klein2Tracker Power System Introduction & requirements Ongoing activities Open questions Next steps Summary & conclusions

Motivation Katja Klein3Tracker Power System 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)

Powering Schemes Katja Klein4Tracker Power System 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. [...] It is important that design decisions taken during this process do not preclude reverting to the back-up solution at a later date.” Two powering schemes are widely discussed in the SLHC community: Serial Powering and Powering via DC-DC converters Converter C converts a “high“ DC input voltage to voltage needed by detector D (V 0 ) Conversion ratio r = V 0 / V in < 1  Lower input currents and power losses: P drop = R cab  I 0 2  r 2

Switching noise Buck Converters Katja Klein5Tracker Power System Inductor-based converters provide large currents and are very efficient - the buck converter is often studied as the simplest inductor-based variant Ferrites saturate for B > ~2T  air-core inductor needed Efficiency V in  12V  HV-tolerant semi-conductor technology needed  radiation-hardness Material budget Space constraints radiates noise bulky Schematic scheme of a buck converter (feedback control loop not shown)

“Charge Pump“ = Switched Capacitors Katja Klein6Tracker Power System 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!) Many switches  noise, losses Must be rad.-hard and tolerate V in Efficiency No regulation (costs efficiency) Lowish currents

Strip Power System Requirements Katja Klein7Tracker Power System 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 Note: some of these requirements are in conflict to each other Must find compromise

Power WG Activities Katja Klein8Tracker Power System Topic / SchemeElectronics developmentSystem testsMaterial budget DC-DC conversion (baseline solution) Non-isolated inductor-based: CERN (technology, ASIC development, simulation); Aachen (PCB); Bristol (air-core coil) Aachen (strips)Aachen Transformer-based: Bristol Fermilab, Iowa, Mississippi (pixels) Charge pump: PSI (pixels); CERN (strips) Piezo-electric transformer: - Serial powering (back-up solution) (Fermilab)Fermilab, Iowa, Mississippi (pixels); Rochester? (strips) Aachen ImplementationKarlsruhe (Powering via cooling pipes): on hold Power supplies, cables: not covered Many useful projects, can only indicate main lines of activity here

Phase-1: Power to the Pixels Katja Klein9Tracker Power System 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  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

On-Chip Charge Pump for Pixels Katja Klein10Tracker Power System cap+ cap- VDD Vout del clk SW1 GND SW2SW3 f [MHz] P_SCP_RiPout 102 %14 %84 % 204 %15 %81 % 408 %18 %74 % Prototype by PSI (`08) Conversion ratio 1:2 I out = 24mA (1 ROC) 0.25  m IBM CMOS Ext. capacitors (10-100nF) Test of noise behaviour with ROC to be done Future options: version for 1 module (16 ROCs); ratio 2:3 5 mV/div Output voltage ripple (f=4MHz, C=10nF) Charging Discharging

Pixel Power Distribution Studies Katja Klein11Tracker Power System 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

Development of Converter ASICs Katja Klein12Tracker Power System 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 = 3.3 – 12V V out = 1.2, 1.8, 2.5, 3.0, 5.0V I out < 3A f s = 400kHz – 3MHz

Development of Converter ASICs Katja Klein13Tracker Power System 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 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

Strip Tracker System Tests Katja Klein14Tracker Power System 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

Total MB of: TEC modules TEC Converters 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) Simulation of Strip Material Budget Katja Klein15Tracker Power System Original TEC TEC with buck converters r = 1/8 TEC electronics & cables: % 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)

Tasks / Open Questions & Next Steps: Pixels Katja Klein16Tracker Power System 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)

Tasks / Open Questions & Next Steps: Strips Katja Klein17Tracker Power System 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

Tasks / Open Questions & Next Steps: Strips Katja Klein18Tracker Power System 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, ?) 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)

Summary & Conclusions Katja Klein19Tracker Power System 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

Back-up Slides Katja Klein20Tracker Power System

R&D Proposals relevant for Power WG Katja Klein21Tracker Power System 07.01: R&D on Novel Powering Schemes for the SLHC CMS Tracker07.01: 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 groups07.08: 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 SLHC08.02: 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 Tracker08.04: 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

Open Tasks Katja Klein22Tracker Power System 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