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HV MUX motivation and principle HV MUX devices requirements Real time test system and test results

High Voltage MUX for ATLAS Tracker Upgrade EG Villani STFC RAL on behalf of the ATLAS HVMUX group TWEPP-14, 22 – 26 Sept. 2014. Outline. HV MUX motivation and principle HV MUX devices requirements Real time test system and test results Conclusions. ATLAS Phase II Tracker Upgrade.

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HV MUX motivation and principle HV MUX devices requirements Real time test system and test results

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  1. High Voltage MUX forATLAS Tracker UpgradeEG Villani STFC RALon behalf of the ATLAS HVMUX groupTWEPP-14, 22 – 26 Sept. 2014

  2. Outline • HV MUX motivation and principle • HV MUX devices requirements • Real time test system and test results • Conclusions

  3. ATLAS Phase II Tracker Upgrade • Phase 2 (HL-LHC) • Replacement of the present Transition • Radiation Tracker (TRT) and Silicon • Tracker (SCT) with an all-silicon • strip tracker Conceptual Tracker Layout • Challenges facing HL-LHC silicon detector upgrades • Higher Occupancies ( 200 interactions / bunch crossing) • Finer Segmentation • Higher Particle Fluences ( 1014outmost layers to  1016 innermost layers • Increased Radiation Tolerance ( 10increase in dose w.r.t. ATLAS ) • Larger Area (~200 m2) • Cheaper Sensors • More Channels • Efficient power/bias distribution / low material budget Short Strip (2.4 cm) -strips (stereo layers): Long Strip (4.8 cm) -strips (stereo layers): r = 38, 50, 62 cm r = 74, 100 cm From 1E33 cm-2 s-1 …to 5E34 cm-2 s-1 TWEPP-14 25/09/2014 1

  4. HV distribution in ATLAS Upgrade HV SW HV SW • The ‘ideal’ solution would be one HV bias line for each sensor: • High Redundancy; • Individual enabling or disabling of sensors and current monitoring; • But the increased number of sensors in the Upgraded Tracker implies a trade off among material budget, complexity of power distribution and number of HV bias lines. • Use single (or more) HV line to power all sensors in a ½ stave and use one HV switch under DCS control for each sensor to disable malfunctioning detectors. TWEPP-14 25/09/2014 2

  5. The Stave concept andHV distribution in ATLAS Upgrade • Designed to reduce radiation length • Minimize material by shortening cooling path • 13x2Modules glued directly to a stave core with embedded pipes • Designed for mass production • Simplified build procedure • Minimize specialist components • Minimize cost ~ 1.2 meters Carbon fiber facing Stave Cross-section Bus cable A Stave250 Carbon honeycomb or foam Coolant tube structure Hybrids TWEPP-14 25/09/2014 3

  6. HV distribution in ATLAS Upgrade TWEPP-14 25/09/2014 4

  7. HV devices requirements • High Voltage switches strip detector requirements: • Must be rated to 500V plus a safety margin; • Must be radiation hard, nominal maximum expected 1x1015 neq/cm2 ,  30Mrad (Si) for end cap. Multiply by (up to) 2 to include safety margin; • On-state impedance Ron << 1kΩ// Ion 10mA (for irradiated sensors) • Off-state impedance Roff>> 1GΩ // Ilkg<< Isens • Must be unaffected by magnetic field; • Must maintain satisfactory performance at -30 C; • Must be small (area constraint) and cheap (around 1E4 needed) TWEPP-14 25/09/2014 5

  8. HV devices investigated HV Si, SiC and GaN based devices are being investigated FAILED FAILED FAILED FAILED FAILED PASS – N.A. FAILED FAILED FAILED FAILED FAILED T.B.T. PASS – need conf. TWEPP-14 25/09/2014 6

  9. Si JFET 2N6449 Vg JFET4 Ids Igs PCB JFETs JFET3 Vds=285V Background Vds=150V Pre irradiation Vg Ids Vg JFET4 Vgs Vgs PCB JFETs JFET3 Ig Ids Ig Ids Post irradiation TWEPP-14 25/09/2014 7

  10. Real Time HV devices radiation tests HV Vds and Ids tot HV 2410 15 m IEEE488/USB 2602 ½ 2602 ½ Q1 Q2 Is Is 2602 ½ 2602 ½ Vgs and Igs Particle Beam Source meters PC - Labview • Real time HV devices test system: it allows monitoring devices’ behaviour when irradiated • Real time Monitoring of rds and Ids vs. Vgs vs. particle fluence • Data are saved at 1 sample/sec for offline analysis • Two devices simultaneously, it can be used for generic real-time testing of devices under radiation TWEPP-14 25/09/2014 8

  11. HV mounting frame Plexiglas Frame with X-Y adjustments to mount DUT HV devices. PCB to hold up to 4 HV devices cool box PCB in the cool box TWEPP-14 25/09/2014 9

  12. HV mounting frame cool box Level of radiation near the cool box after an irradiation test. Beam alignment checked with photo film on area where DUTs are placed TWEPP-14 25/09/2014 10

  13. HV devices radiation tests EPC2012 EPC2012 CPMF-1200 2N6449 • A number of HV devices tested at Birmingham last weeks, including: • EPC2012 (GaN FET) • CPMF-1200 (SiCMOSFET) • 2N6449 (Si JFET) TWEPP-14 25/09/2014 11

  14. Irradiation test synopsis EPC2012 EPC2012: rds @ constant mA’s test; Vds test at 150 V, 1mA compliance, Vgs =[-1, 3]V/20mV time Annealing + Ids plots: 5 mins Rds measurement: 1 min 4 6 8 10 10 10 10 10 10 10 Rds measurement mA RAD RAD RAD RAD RAD RAD RAD RAD RAD RAD • EPC2012: • 20irradiation phases, 0.5minute/ each @ Beam current 0.2 μA = 1.25e12 p+ /sec. • Restphases in between irradiation phases around 5 minutes • Ids bias current increasingly higher, to emulate sensors leakage with dose TWEPP-14 25/09/2014 12

  15. HV devices radiation tests beam sequence Annealing + Ids plots: 5 mins Rds measurement: 1 min RAD RAD RAD RAD RAD RAD RAD RAD RAD RAD time * At Beam current 0.2 μA = 1.25e12 p+ /sec.* For 26MeV p+ 2e15 1MeV n-eqv in ≈ 533 seconds (in Si – no data for GaN) *20 irradiation phases of 30 seconds/each = 2.25e15 1MeV n-eqv(estimated MAX fluence for Strips is 2e15 1MeV n-eqv, including x2 safety factor) * Max ΔT ≈4.5°C/sec TWEPP-14 25/09/2014 13

  16. Constant Ids for rds measurement EPC devices radiation tests results DUT1/2 alternately ON Vgs sweep Irradiation phases TWEPP-14 25/09/2014 14

  17. EPC devices radiation tests results Is1, Is1 Vgs sweep Vds Irradiation phases Magnified Time plots of board B DUTs Is1/2 during the radiation test. TWEPP-14 25/09/2014 15

  18. EPC devices radiation tests results Irradiation phases 30 sec/each Vgs sweep Time plots of board B DUT 1 Ig during the radiation test. Irradiation phases (30 + 30 sec.) TWEPP-14 25/09/2014 16

  19. EPC devices radiation tests results Vds=150V Vgs=3V Average and 1 σ deviation Is and Ig Leakage current @Vds=150V, Vgs=0V. Average Ig and 1 σ @Vgs=3V (device fully on). Average rdson< 2Ohm @Vgs=3V TWEPP-14 25/09/2014 17

  20. Stacked configuration for high voltages • We could use HV devices rated for lower voltage than needed and stack them on each other to achieve higher voltage switching • the biasing circuit needs careful designing, to avoid overvoltages and / or excessive leakage • Modeled circuit with parasitic resistor values taken from measurements of our own EPC devices. Not part of circuit; just mimics actual measured leakage currents Also not part of circuit TWEPP-14 25/09/2014 18

  21. Stacked configuration for high voltages Vload measured Vload simulated TWEPP-14 25/09/2014 19

  22. Stacked configuration for high voltages First Pass Estimating Size of EPC2012 Circuit • Used only commercial components • Did not do real layout • Size is large but optimization possible TWEPP-14 25/09/2014 20

  23. Conclusions • High Voltage distribution via HV switches and DCS control is being investigated. A test system has been developed to allow real time monitoring of the DUTs during irradiation. • A number of devices, based upon Si and wider band gap materials, are being investigated. GaN seems promising, will need to be confirmed. • The control circuitry to enable and disable the HV switches also being investigated. • Thank you! TWEPP-14 25/09/2014 21

  24. Backup - HV devices example plots – EPC2012 Igs(A) Ids(A) Vgs(V) Vgs(V) EPC2012 Igs vs. Vgs, Vds max = 200V EPC2012 Ids vs. Vgs, Vds max = 200V, Ids compliance= 1mA DUT#1 , Board A GaN devices rated for up to 200V ( up to 600V would be needed for HV MUX but stacked configuration possible – see later slides) TWEPP-14 25/09/2014 I

  25. Backup - HV MUX control scheme Negative HV multiplier To Detector HV JFETDEPL filter V source -HV • Regardless of the devices used as HV switches, a control circuitry, referenced to a high potential, to enable them is needed • An investigated option consists of an AC coupled control switch based upon a voltage multiplier (it works with depletion and enhancement mode devices depending on the polarity of the diodes ) TWEPP-14 25/09/2014 II

  26. Backup - HV MUX control scheme test fin= 50 kHz Vbias =0V fin= 100 kHz Vbias =0V fin= 50 kHz Vbias =-300V fin= 50 kHz Vbias =-300V Multimeter : Fluke 287Signal generator: Tektronix AFG3252HV PSU: EA-BS315-04B (#2 in series to get 300V) V MPY Vout (Meter) ‘MOBO’ ‘DABO’ connection Vin (Sign. Gen) (HV PSU) Voltage MPY * The voltage across R2 is measured vs. amplitude and frequency of Vin ( square wave, 50% duty cycle) and for Vhigh = [0, -300] V * Applying -300 V a slight decrease in abs(Vout) is noticed (some leakage current over the board surface is the likely cause) TWEPP-14 25/09/2014 III

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