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)

Katja Klein Tracker Power System 3

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

Katja Klein Tracker Power System 9

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

Katja Klein Tracker Power System 14

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)

Katja Klein Tracker Power System 16

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

Katja Klein Tracker Power System 17

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