Status Report of the Tracker Upgrade Power Working Group CMS Upgrade Workshop, Fermilab November 20 th, 2008 Katja Klein 1. Physikalisches Institut B RWTH Aachen University

The Tracker Upgrade Power WG Katja Klein2Status Report of the Tracker Upgrade Power WG Provision of the required power to the front-end electronics has been identified as one of the major challenges for the Tracker Upgrade at SLHC.  A working group has been established in April 2008 Convenor: K. K. ; second convenor yet to be appointed Meets roughly every two months  Three meetings so far Task of the WG: Identify and investigate novel powering schemes; identify and develop a solution (solutions) for the tracker subsystems; develop a working system including all relevant components.

Powering Schemes Katja Klein3Status Report of the Tracker Upgrade Power WG V drop = R  I 0 P drop = R  I Classical grounding, readout & communication + Flexible: different voltages can be provided + Several conversion steps can be combined – Radiation-hard, HV and magnetic field tolerant DC-DC converter to be developed – Converter efficiency 70-90% – Converters are switching devices  noise – Inductors must have air-cores  noise Parallel powering with DC-DC conversion Conversion ratio r = V out / V in << 1 P drop = R  I 0 2  n 2  r 2 + Many modules can easily be chained + No noise problems observed so far – Each module has its own ground potential – All communication must be AC-coupled – Shunt regulator and transistor to take excess current and stabilize voltage  Significant local inefficiency – Safety issues Serial powering

The Buck Converter (Inductor-Based) Katja Klein4Status Report of the Tracker Upgrade Power WG The “buck converter“ is the simplest inductor-based step-down converter: Switching frequency f s : f s = 1 / T s Can provide relatively large currents (several Amps) Technology must work in a 4T magnetic field  since ferrites saturate at lower fields, air-core inductors must be used Need to find compromise between high efficiency (low f s ) and low noise (high f s ) Discrete components (coil, capacitors,...) need space and contribute to material Convertion ratio r < 1: r = V out / V in = D Duty cycle D: D = T 1 / T s

Isolated Converters (Transformer-Based) Katja Klein5Status Report of the Tracker Upgrade Power WG The “forward converter“ is the most commonly used isolated buck converter: r = n 3 /n 1  D D  1 / (1 + n 2 /n 1 ) DC isolation between input and output Multiple outputs with different voltages are possible Magnetic energy is transfered, not stored → low noise Air-core transformer needed More components → more material and higher space demand

The Charge Pump (Capacitor-Based) Katja Klein6Status Report of the Tracker Upgrade Power WG Inductorless technology Everything but capacitors is integrated on-chip  low mass, low space Provides relatively low currents (~ 1A) Fixed “quantized“ conversion ratio (e.g. r = ½) Output voltage cannot be controlled by feedback loop Switching noise S tep-down layout: capacitors charged in series & discharged in parallel In → n = number of parallel capacitors I out = n  I in r = 1 / n

Relevant R&D Proposals Katja Klein7Status Report of the Tracker Upgrade Power WG 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

Summary of Activities Katja Klein8Status Report of the Tracker Upgrade Power WG SchemeElectronics developmentSystem testsMaterial budget DC-DC conversionNon-isolated inductor-based: CERN (technology, chip development, simulation); Aachen (PCB); Bristol (air-core coil) Aachen (strips)Aachen Transformer-based: Bristol Fermilab, Iowa, Mississippi (pixels) Charge pump: PSI Piezo-electric transformer: - Serial poweringFermilab, Iowa, Mississippi (pixels) Aachen OthersKarlsruhe (Powering via cooling pipes)

DC-DC Converter Development (CERN) Katja Klein9Status Report of the Tracker Upgrade Power WG F. Faccio, St. Michelis et al. (not CMS, but CERN electronics group; good relations) Buck controller chip “SWREG2“ based on Pulse Width Modulation; in HV compatible AMIS I3T80 technology (0.35  m CMOS) PCB designed and manufactured by Aachen Submission of second prototype chip to AMIS planned for December `08 Most crucial issue is to identify a radiation-hard HV compatible technology V in = 3.3 – 20V V out = 1.5 – 3.0V I out = 1 – 2A f s = 250kHz – 3MHz A prototype ASIC buck converter for LHC upgrades, St. Michelis et al., TWEPP-08

DC-DC Converter Development (CERN) Katja Klein10Status Report of the Tracker Upgrade Power WG Many more activities:  Topology optimization, see below Custom DC-DC converters for distributing power in SLHC trackers, St. Michelis, TWEPP-08 Custom DC-DC converters for distributing power in SLHC trackers, St. Michelis, TWEPP-08  Noise measurements, e.g. with TOTEM modules Noise Susceptibility Measurements of Front-End Electronics Systems, G. Blanchot, TWEPP-08 Noise Susceptibility Measurements of Front-End Electronics Systems, G. Blanchot, TWEPP-08  Converter and inductor simulation

Novel Powering Schemes (Aachen) Katja Klein11Status Report of the Tracker Upgrade Power WG Petal Motherboard (ICB) Ring 6 modules System test measurements with End Cap petal Commercial buck converters (Enpirion, Micrel) with ferrite and air-core inductors tested Custom PCB to integrate converter into system E.g. Enpirion EQ5382D:  f s = 4MHz  V in = 5.5V  V out = 1.25V / 2.5V

Novel Powering Schemes (Aachen) Katja Klein12Status Report of the Tracker Upgrade Power WG Significant increase of raw noise, in particular with air-core inductor Both conductive and radiative contributions Toroids create less noise than solenoids Linear DropOut regulator reduces conductive noise Shielding helps Increasing the distance between converter and hybrid helps Custom converters (CERN buck, LBNL charge pump): ~20% increase due to conductive noise System Tests with DC-DC Converters for the CMS Silicon Strip Tracker at SLHC, K. Klein et al., TWEPP-08 No converter 2.5V via S type 0.60 MHz 0.75 MHz 1.00 MHz 1.25 MHz CERN buck No converter Toroid Toroid with LDO Toroid, LDO, 30  m Al shield

Katja KleinStatus Report of the Tracker Upgrade Power WG13 Novel Powering Schemes (Aachen) Standardized EMC set-up to measure Differential & Common Mode noise spectra (similar to set-up at CERN) PS Spectrum analyzer Load Line impedance stabilization network Copper ground plane Current probe Spectrum Analyzer Load Enpirion 2.5V at load Common mode fsfs Enpirion 2.5V at load Differential Mode SWREG2 V out = 2.5V Common Mode SWREG2 V out = 2.5V Differential Mode Next steps: optimization of converter integration; noise injection studies Lutz Feld,

Air-Core Magnetic Components (Bristol) Katja Klein14Status Report of the Tracker Upgrade Power WG Toroidal air-core inductor manifactured into PCB  35  m copper layers, 30 turns  L = (240 ± 20)  H (at 100kHz)  R DC = (205 ± 20) m   too high Next step: develop inductor with lower resistance To be used in Aachen system test measurements Power Distribution in a CMS Tracker for the SLHC, D. Cussans et al., TWEPP-08

Air-Core Magnetic Components (Bristol) Katja Klein15Status Report of the Tracker Upgrade Power WG Air-core planar transformer for transformer-based converters Finite Element Modelling of magnetic field  Primary current 0.25A, without load: 287nT at 10cm  Primary current 0.25A, 1A load current: 12nT at 10cm  35  m copper shield at 200  m distance: 60pT at 10cm, resistive loss = 2.8mW Next step: development of transformer-based converter (15V  1.3V) Other activities: single module ARC test-stand, EMC test stand 4:1 prototype I p = 0.25A I s = 0A I s = 1A

Powering Distribution Studies (US) Katja Klein16Status Report of the Tracker Upgrade Power WG Simon Kwan, Dedicated power board within CAPTAN DAQ system used for power studies Focus is on pixel subsystem Test of off-the-shelf DC-DC converters + regulators Test of serial powering with Serial Powering Interface Chip (SPi) Reliability study and failure mode analysis, system modelling No results yet

Development of On-Chip Charge Pump (PSI) Katja Klein17Status Report of the Tracker Upgrade Power WG Beat Meier, cap+ cap- VDD Vout del clk SW1 GND SW2SW3 f [MHz] P_SCP_RiPout 102 %14 %84 % 204 %15 %81 % 408 %18 %74 % For pixel detector  needed for 4th layer  derive V ana from V dig Divide-by-2 prototype I out = 24mA (1 ROC) 0.25  m IBM CMOS External capacitors First measurements performed: efficiency, voltage ripple Next step: combine with ROC & measure noise behaviour 5 mV/div Output Voltage: low ripple ChargingDischarging

Powering via Cooling Pipes (Karlsruhe) Katja Klein18Status Report of the Tracker Upgrade Power WG - ~50A ~1A Max. delta V=43 mV Max. delta V=1,89 mV Proposal by Wim de Boer (Karlsruhe): CO 2 cooling pipes used as power leads Measurements with dummy rod and heater foils have started Many open questions: noise pick-up, safety,... Jochen Ebert, Pipe x-section varies along length of pipe I

Upgrade Task Force on Powering Systems Katja Klein19Status Report of the Tracker Upgrade Power WG Mandate for Tracker Upgrade Task Force on Powering Systems The Task Force will review all the currently proposed solutions for powering an upgraded CMS Tracker and will propose a baseline solution and one back-up solution for powering the upgraded Tracking Systems. The Task Force will involve those currently responsible for the Powering R&D projects, experts on Powering Systems, experts on Power Transmission, Grounding and Shielding and experts on control and safety systems. The Task Force will report in January The Report will be supported with the documentation provided by the experts to the Review. A task force, chaired by Peter Sharp, has been established by Geoff. It should discuss and compare different schemes (SP vs. DC-DC) and make a recommendation to the working group. Members: Peter Sharp (chair), Fernando Arteche, Guido Dirkes, Federico Faccio, Lutz Feld, Frank Hartmann, Roland Horisberger, Marvin Johnson, Katja Klein, Alessandro Marchioro, Beat Meier, Mark Raymond.

Today‘s Meeting Katja Klein20Status Report of the Tracker Upgrade Power WG Charge (by Geoff and Daniela): Phase I power issues: How must pixel electrical services change to allow evolution to a fourth layer and increased endcaps? What voltages and currents will be required? Opinions from pixel system regarding possible DC-DC vs serial power. What components must be developed, by when?