1. Rutherford Appleton Laboratory Particle Physics Department 1 Serial Powering Scheme Peter W Phillips STFC Rutherford Appleton Laboratory On behalf of RAL group and collaborators

2. Rutherford Appleton Laboratory Particle Physics Department 2 Motivations Fewer Cables Fewer Connections Increased Efficiency Reduced Material Concerns noise/electrical performance –In fact SP systems are clean: local regulation helps chain current constant, therefore no IR drops Failure in the chain – loss of many modules …

3. Rutherford Appleton Laboratory Particle Physics Department 3 SPPCB - 2006 - 111 mm x 83 mm SSPPCB - 2006/7 - 38 mm x 9 mm Hybrid SSPPCB ABCD3TV2 Evolution of Serial Powering Circuitry SPPCB - 2006 - 150mm x 150mm AG Analog power AV DG Digital pwr DV DataCmd Clk

4. 4 Tests with SCT modules or 4 chip hybrids ENC of IP vs. SP ENC with injection of external voltage pulse into power line ( 1V pp through 15 pF) ENC with current modulation of 20 mA SCT module test set-up

5. Rutherford Appleton Laboratory Particle Physics Department 5 Interface PCB Cooling hoses with connector Module 0 Module 1 Hybrid 2 Module 3 Module 4 Module 5 Picture of the 6-module stave on a bonding fixture. Module 2 is a bare hybrid without sensor for better comparison with single-hybrid data. The interface PCB at the end of the stave (top of the picture) carries a connector. All other stave electrical connections are made through wire- bonds. The cooling hoses (inlet and outlet) are at the top end of the stave.

6. Rutherford Appleton Laboratory Particle Physics Department 6 HV from storage capacitors & LVDS power from bench supply

7. Rutherford Appleton Laboratory Particle Physics Department 7 Low output impedance crucial to achieve good ‘grounding’ and reduce picked up noise Dynamically each sensor is grounded to current source Option of using single HV supply for several sensors No difference in performance is seen with the 6 module stave Single HV line Separate HV lines for each sensor

8. Rutherford Appleton Laboratory Particle Physics Department 8 Module with 3cm detector Three 6-chip hybrids operated as a serial chain Next step: 30 module stave with commercial SP electronics Data/clock/command Linear regulator ST SR AC-coupling Work in Progress: Being built at LBNL

9. Rutherford Appleton Laboratory Particle Physics Department 9  10 + 10 modules back-to-back  10 cm * 10cm sensors  40 ABC-Next chips/module  Custom SP circuitry Next Year: Short Strip “Supermodule”

10. Rutherford Appleton Laboratory Particle Physics Department 10 SP Architecture Choices a) External shunt regulator + external power transistor External commercial SR+ ST, used for RAL studies with SCT modules. With custom electronics could be part of one chip. This is good engineering, but implies a high-current device; limited expertise in HEP IC community. Constant current source ROIC ROIC Module 1 Module n Voltage chain  5 V  2.5 V 0 V We will test this with SPI chip

11. Rutherford Appleton Laboratory Particle Physics Department 11 b) Shunt regulator + transistor in each ROIC Integrated (custom) SR and transistor designed by Bonn worked well for pixels. Many power supplies in parallel; Addresses high-current limitation and provides protection. Difficulty is matching and switch-on behaviour of shunt transistors. Must avoid hot spots that kill one shunt transistor after the other. We will test this with ABC_Next (and SPi LVDS buffers) SP Architecture Choices

12. Rutherford Appleton Laboratory Particle Physics Department 12 c) External shunt regulator + integrated parallel power transistors New attractive idea. Addresses high-current limitation. Conceptually simple. Need to understand how well distributed feed-back works. Will test this with SPi (for Shunt Regulator and buffers) and ABC_Next (for Shunt Transistor) SP Architecture Choices

13. Rutherford Appleton Laboratory Particle Physics Department 13 Expected benefit of custom SP circuitry Dynamic impedance: reduced by one or two orders of magnitude! Measurement (G Villani): Prototype with commercial components Simulation (M Newcomer): External Shunt Regulator and Integrated Shunt Transistors

14. Rutherford Appleton Laboratory Particle Physics Department 14 30 module ABCD stave Evaluation of custom circuitry –ABC_Next and SPi 20 module ABC-Next “Supermodule” Design protection schemes G&S evaluation of SP systems –important but not expected to be a concern Design of constant-current source (Prague (JS) + RAL) Hybrid Outlook