Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 1

Serial Powering of Pixel Modules

T. Stockmanns, P. Fischer, O. Runolfsson and N. Wermes

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 2

Why serial powering?

CC

CV CV CV CV CV CV

or

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 3

Power consumption

• Every ATLAS - pixel module needs:

– 2 supply voltages:

Name Voltage Current Power

VDDA 1.7 V 970 – 1290 mA 1650 – 2200 mW

VDD 2 V 500 – 800 mA 1000 – 1320 mW

Sum 1.5 - 2 A

Total detector

(1750 modules)

2 V 3500 A

– 1 HV bias connection– 3 ground lines

6power linesper module

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 4

Cable

Powersupply

PP 3 PP 2

PP 1PP 0

120 m

20 m

9 m

2,8 m

0,5 V

1 V

0,5 V

0,55 V

< 0,5 m

Pixel detector

Modules

3V

Add. 1 V

cable costs cable size

cable mass

Total distance: 152 mMaximum voltage drop: 6.5 VOptimum: No cables at all

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 5

16FE FEModule 1

VDDA VDD

Regulator

16FE FEModule 2

VDDA VDD

Regulatorconstant voltagepower supply

constant voltagepower supply

Parallel Powering

• For a stave of 13 modules:

- power + sense lines: 104

- supply voltage: 2 V / 1,7 V

- supply current: 26 A

- power consumption: 47 W

+ voltage drop: 226 W

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 6

readout

readout

readout

On chip On chip

16

I0

FE FE

16FE FE

16FE FE

Module 1

Module 2

Module 13

ConstantCurrentPowerSupply

Alternative: Serial Powering

shunt regulator

VDD

linear regulator

VDDA

26 V

24 V

24 V

20 V

2 V

0 V

• For a stave of 13 modules:

- power + sense lines: 2

- supply voltage: 26 V

- supply current: 2 A

- power consumption: 52 W

+ voltage drop: 65 W

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 7

Pros and Consof both concepts

Parallel Powering Serial Powering

Pros Cons

• Individual control of each module • Difficult to switch off a single module

• No risk for the full chain • Risk to loose a full chain

• Possible noise crosstalk via power lines

Cons Pros

• low voltage + high current high voltage drop

• high voltage + low current low voltage drop

• high total power of pixel detector • lower power consumption of pixel detector

• one power supply per module • one power supply per chain

• large amount of cables • less amount of cables

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 8

Shunt regulators

• 10 shunt regulators built with commercial ICs• All of them operated in series• 2 modified to work with the required voltage• water cooled

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 9

Parallel readout of 2 serially powered modules

VME - Crate

PCC

PCC

Module 1

2 A

Module 2

PLL 1 + 2 PixDAQ 1 + 2

Shunt -Regulators

Linear -Regulator

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 11

No influence on module performance

Threshold: 4700 e-

Dispersion: 480 e-

Noise: 150e- / 250 e-

Serial powered Parallel powered

Threshold: 4330 e-

Dispersion: 300 e-

Noise: 148 e-

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 14

Integration of regulators in newest FE-chip

1,3 1,4 1,5 1,6 1,7 1,8 1,9 2,0 2,1 2,2

1,25

1,30

1,35

1,40

1,45

minimum dropout voltage 0.285V

Linear regulator Iout

= 60mA

Ou

tpu

t vo

ltag

e [V

]Input voltage [V]

0,0 0,5 1,0 1,5 2,0 2,5 3,0-2000

0

2000

4000

6000

8000

10000

12000

14000Shunt regulator

Slope = 1 / 33.4

- 60C

210C

curr

ent

[µA

]

voltage [V]

shunt regulator and linear regulator implemented and tested in the newest radhard version of the FE-chip

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 15

Threshold measurement

4 FE-I chips in parallel 1 + 2 chips in series

FEIFEIFEIFEICCCC

FEI

FEI FEI

Threshold: 4680 e-

Dispersion: 100 e-

Noise: 264 e-

Threshold: 4780 e-

Dispersion: 105 e-

Noise: 268 e-

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 16

Serial PoweringSensorless Module

• 13 working chips

• 37120 working pixels

typ.Threshold: 4800 e-

Dispersion: 1340 e- 1200 e-

(untuned!)Noise: 214 e- 160 e-

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 17

Summary

• Serial Powering of pixel detectors seems to be possible:

– Feasibility of serial powering proven with external regulators

– Regulators implemented into the new radiation hard FE-chips

– Internal regulators tested on single chips and modules

– electrical performance very similar hope that the differences in noise disappear with new version of regulators

• Next steps:

– Using several modules in a series– Measuring the performance of the modules depending on

different situations– Testing possible failure scenarios

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 18

„On Module“ – Serial Powering

• On each side of a module the FE-chips are connected in series Current consumption goes down by a factor of 8 with an 8-times higher voltage

• Opposite FE-chips are on the same DC-potential

ConstantCurrent

16 V14 V12 V10 V8 V6 V4 V2 V

16 V14 V12 V10 V8 V6 V4 V2 V

Vertex 2002, Kailua-Kona 7.11.2002 Tobias Stockmanns, Universität Bonn 19

„On Module“ – Serial Powering

• Implementation:

– AC-coupling between FE-chips and MCC necessary

– Special sensor design necessary

• Disadvantage:

– More complicated module design

• Advantages:

– low current consumption

– no risk of loosing a chain of modules

– individual module operation like in parallel powering