High Voltage MUX forATLAS Tracker Upgrade

EG Villani STFC RALon behalf of the ATLAS HVMUX group

TWEPP-14, 22 – 26 Sept. 2014

• HV MUX motivation and principle

• HV MUX devices requirements

• Real time test system and test results

• Conclusions

Outline

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ATLAS Phase II Tracker Upgrade

Challenges facing HL-LHC silicon detector upgrades

•Higher Occupancies ( 200 interactions / bunch crossing)

⤷ Finer Segmentation•Higher Particle Fluences ( 1014 outmost layers to 1016 innermost layers

⤷ Increased Radiation Tolerance ( 10 increase in dose w.r.t. ATLAS )

•Larger Area (~200 m2)⤷ Cheaper Sensors

•More Channels⤷ Efficient power/bias distribution / low

material budget

Phase 2 (HL-LHC)Replacement of the present TransitionRadiation Tracker (TRT) and Silicon Tracker (SCT) with an all-silicon strip tracker

Conceptual Tracker Layout

Short Strip (2.4 cm) -strips (stereo layers):Long Strip (4.8 cm) -strips (stereo layers):

r = 38, 50, 62 cmr = 74, 100 cm

From 1E33 cm-2 s-1 …to 5E34 cm-2 s-1

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HV distribution in ATLAS Upgrade

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.

2

HV SW

HV SW

The Stave concept andHV distribution in ATLAS Upgrade

3

~ 1.2 metersBus cable

Hybrids Coolant tube structure

Carbon honeycomb or foam

Carbon fiber facingStave Cross-section

A Stave250

• Designed to reduce radiation length Minimize material by shortening cooling path 13x2 Modules glued directly to a stave core with

embedded pipes• Designed for mass production

Simplified build procedure Minimize specialist components Minimize cost

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HV distribution in ATLAS Upgrade

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HV devices requirements

5

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)

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HV devices investigatedHV Si, SiC and GaN based devices are being investigated

6

FAILED

FAILED

FAILED

FAILED

FAILED

FAILED

PASS – need conf.

T.B.T.

FAILED

FAILED

FAILED

PASS – N.A.

FAILED

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BackgroundPCB JFETsIds Igs

Ids

Vg

VgVg

Pre

irrad

iatio

n

JFET3

JFET4

Si JFET 2N6449Vds=285V

Vds=150V

PCB JFETsIds Ig Ids Ig

Vgs

JFET3

Vgs

JFET4

Post

irra

diati

on

7

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Real Time HV devices radiation tests

8

• 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

IEEE488/USB2602

½

HV Vds and Ids tot

Vgs and Igs

Is

2602 ½

2602 ½

Is

15 m

Source meters

Q1 Q2

HV 2410

2602 ½

PC - LabviewParticle Beam

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HV mounting frame

9

Plexiglas Frame with X-Y adjustments to mount DUT HV devices.

PCB to hold up to 4 HV devices

PCB in the cool box

cool box

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HV mounting frame

10

Beam alignment checked with photo film on area where DUTs are placed

cool box

Level of radiation near the cool box after an irradiation test.

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HV devices radiation tests

11

• A number of HV devices tested at Birmingham last weeks, including:• EPC2012 (GaN FET)• CPMF-1200 (SiC MOSFET)• 2N6449 (Si JFET)

EPC2012

CPMF-1200

2N6449

EPC2012

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Irradiation test synopsis

12

EPC2012

EPC2012: rds @ constant mA’s test; Vds test at 150 V, 1mA compliance, Vgs =[-1, 3]V/20mV

time

RAD RAD RAD RAD RAD RAD RAD RADRAD RAD

Annealing + Ids plots: 5 mins

Rds measurement: 1 min

EPC2012: • 20 irradiation phases, 0.5 minute/ each @ Beam current 0.2 μA = 1.25e12 p+ /sec.• Rest phases in between irradiation phases around 5 minutes• Ids bias current increasingly higher, to emulate sensors leakage with dose

4 6 8 10 10 10 10 10 10 10 Rds measurement mA

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time

13

RAD RAD RAD RAD RAD RAD RAD RADRAD RAD

* 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

HV devices radiation tests beam sequenceAnnealing + Ids plots: 5 mins

Rds measurement: 1 min

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Constant Ids for rds measurement

14

EPC devices radiation tests results

Irradiation phases

Vgs sweep

DUT1/2 alternately ON

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EPC devices radiation tests results

Vgs sweepIrradiation phases

Is1, Is1

Magnified Time plots of board B DUTs Is1/2 during the radiation test.

Vds

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EPC devices radiation tests results

Irradiation phases 30 sec/each

Vgs sweep

Irradiation phases (30 + 30 sec.)

Time plots of board B DUT 1 Ig during the radiation test.

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EPC devices radiation tests results

Average Ig and 1 @Vσ gs=3V (device fully on).Average and 1 deviation Iσ s and Ig Leakage current @Vds=150V, Vgs=0V.

17

Vds=150V Vgs=3V

Average rdson < 2Ohm @Vgs=3V

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•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.

18

Stacked configuration for high voltages

Not part of circuit; just mimics actual measured leakage currents

Also not part of circuit

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Stacked configuration for high voltages

Vload simulated

Vload measured

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Stacked configuration for high voltages

EP

C20

12

U 1

EP

C2

012U 2

EP

C20

12

U 3

EP

C20

12

U 4

V 1500

V 2 P U L S E (0 3 10n 50n 50n 50n 0 1 )

R 12

500K

D 1

m se1p j

D 2

m se1p j

D 3

m se1p j

D 4B ZG 03C 180

D 5B ZG 03C 180

D 6B ZG 03C 180

D 7B ZG 03C 180

R 17

500K

R 20

500K

R 21

500K

R 9

10K

R 10

10K

R 11

10K

R 13

1G

.tra n 0 200n 0

D etecto r

0402 10k resistors0603 500k resistorsEP C2012600V diode M icroSM PZener DO -219AB (SM F)

10 m m x 15 m m10 m m x 15 m m

First Pass Estimating Size of EPC2012 Circuit

• Used only commercial components• Did not do real layout• Size is large but optimization possible

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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!21

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Backup - HV devices example plots – EPC2012

EPC2012 Ids vs. Vgs, Vds max = 200V, Ids compliance= 1mA EPC2012 Igs vs. Vgs, Vds max = 200V

Vgs(V)

Ids(A) Igs(A)

Vgs(V)

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)

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Backup - HV MUX control scheme

Negative HV multiplier

filter

HV JFETDEPL

V source

• 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 )

-HV

To Detector

II

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0

S V E XC

C 11 0 n

C 21 0 n C 1 8

1 0 0 n

R 22 M e g

R 1

5 k

V h ig h3 0 0 V d c

0

V M P Y

* 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)

‘DABO’ connection

Voltage MPY

‘MOBO’

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

-30.0

-25.0

-20.0

-15.0

-10.0

-5.0

0.0Vbias=0V Vbias=-300Vfin=50KHz fin=100kHz fin=50KHz fin=100kHz

Vin(V) Vout(V) Vout(V) Vout(V) Vout(V)1.0 -4.41 -4.41 -3.91 -4.051.5 -7.05 -7.06 -6.37 -6.402.0 -9.76 -9.80 -8.90 -9.102.5 -12.49 -12.56 -11.50 -11.803.0 -15.22 -15.34 -14.00 -14.503.5 -17.97 -18.12 -16.40 -17.204.0 -20.72 -20.90 -18.95 -19.904.5 -23.47 -23.70 -21.50 -22.605.0 -26.23 -26.50 -24.10 -25.40

fin = 50 kHz Vbias =0V

fin = 100 kHz Vbias =0Vfin = 50 kHz Vbias =-300Vfin = 50 kHz Vbias =-300V

V MPY Vout

Vin

Multimeter : Fluke 287Signal generator: Tektronix AFG3252HV PSU: EA-BS315-04B (#2 in series to get 300V)

(HV PSU)(Sign. Gen)

(Meter)

III

Backup - HV MUX control scheme test