1. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn1 Serial Powering of Pixel Modules T. Stockmanns, P. Fischer, O. Runolfsson and N. Wermes

2. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn2 Why serial powering? or

3. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn3 Power consumption Every ATLAS - pixel module needs: –2 supply voltages: NameVoltageCurrentPower VDDA1.7 V970 – 1290 mA1650 – 2200 mW VDD2 V500 – 800 mA1000 – 1320 mW Sum  1.5 - 2 A Total detector (1750 modules) 2 V3500 A –1 HV bias connection –3 ground lines 6 power lines per module

4. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn4 Cable cable costs cable size cable mass Total distance: 152 m Maximum voltage drop:6.5 V Optimum:No cables at all

5. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn5 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

6. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn6 readout Alternative: Serial Powering shunt regulator VDD linear regulator VDDA 26 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

7. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn7 Pros and Cons of both concepts Parallel PoweringSerial Powering ProsCons 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 ConsPros 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

8. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn8 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

9. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn9 Parallel readout of 2 serially powered modules

10. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn10 Results of the two modules Serial powered Module 1Module 2 Threshold:4700 e - Dispersion:480 e - Noise: 250 e - working pixels:20800 Threshold:4680 e - Dispersion:460 e - Noise: 150 e - working pixels:14400

11. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn11 No influence on module performance Threshold:4700 e - Dispersion:480 e - Noise: 150e - / 250 e - Serial poweredParallel powered Threshold:4330 e - Dispersion:300 e - Noise: 148 e -

12. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn12 Shunt Regulator slope of shunt regulators depends on threshold and current variation higher slope  better stability but: higher slope  more load on lowest regulator Individual Shunt Regs Sum

13. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn13 Shunt Regulator slope of shunt regulators depends on threshold and current variation higher slope  better stability but: higher slope  more load on lowest regulator

14. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn14 Integration of regulators in newest FE-chip shunt regulator and linear regulator implemented and tested in the newest radhard version of the FE-chip

15. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn15 Threshold measurement 4 FE-I chips in parallel1 + 2 chips in series Threshold:4680 e - Dispersion:100 e - Noise: 264 e - Threshold:4780 e - Dispersion:105 e - Noise: 268 e -

16. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn16 Serial Powering Sensorless Module 13 working chips 37120 working pixels typ. Threshold:4800 e - Dispersion:1340 e - 1200 e - (untuned!) Noise: 214 e - 160 e -

17. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn17 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

18. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn18 „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 16 V14 V 12 V10 V8 V6 V4 V2 V 16 V14 V 12 V10 V8 V6 V4 V2 V

19. Vertex 2002, Kailua-Kona 7.11.2002Tobias Stockmanns, Universität Bonn19 „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