Noise Susceptibility Studies /Magnetic Field Tests -

Status & Plans of the Aachen Group

Tracker Upgrade Power WG MeetingJune 4th, 2009

Lutz Feld, Rüdiger Jussen, Waclaw Karpinski, Katja Klein, Jennifer Merz, Jan Sammet

1. Physikalisches Institut B, RWTH Aachen University

Status Report from Aachen 2

Outline

Katja Klein

• Personal & funding• Noise susceptibility studies• Magnetic field test of DC-DC converters• Plans• Summary

Status Report from Aachen 3

Update on Personal

Katja Klein

• Lutz Feld: team leader

• Waclaw Karpinski: electronics engineer– plus electronics workshop team

• Katja Klein: Helmholtz Alliance fellow (4-years from April 08)

• Two PhD students:– Jan Sammet

– Rüdiger Jussen

• Diploma student:– Jennifer Merz (Effect of powering schemes on the material budget)

Status Report from Aachen 4

Funding News

Katja Klein

We have received from BMBF (= main German funding body for HE physics) for the next 3-year funding period, starting July 09:

- invest money- 3 PhD positions for SLHC

Status Report from Aachen 5

Summary of Activities

Katja Klein

• Investigation of system aspects of novel powering schemes– PCB development & system tests separate talk today by Jan Sammet

• Noise susceptibility measurements– Noise injection into silicon strip modules covered in this talk

• Contribute to the development & characterization of magnetic field tolerant and radiation hard DC-DC buck converters, in coll. with CERN PH-ESE group– Magnetic field test covered in this talk

– Integration and test of CERN converters with CMS strip modules only short summary of plans today

• Simulation of material budget of different powering schemes

final results ready, will be presented in the next meeting

Status Report from Aachen 6

Noise Susceptibility Studies

Katja Klein

• Goal: identify particularly critical bandwidth(s) for converter switching frequency

• Bulk current injection (BCI) test-stand has been set up (Rüdiger Jussen)

• A noise current of 70dBA (Ieff = 3.16mA) is injected into the power lines

- Differential Mode (DM) and Common Mode (CM) on 2.5V and 1.25V

Status Report from Aachen 7

BCI Set-up

Katja Klein

• Noise is injected into a single module

• Frequency swept from 100kHz – 100MHz

• Step width: 0.1MHz between 100kHz and 10MHz, 1.0MHz between 10MHz and 30MHz, 2.5MHz between 30MHz and 100MHz

Injection & current probe

Frequency generator

Amplifier

Spectrum analyzer

Powersupplies

LISN

Petal

Current probe in CM configuration

Noise injection into one module (6.4)

Status Report from Aachen 8

Effects on Module Noise

Katja Klein

Status Report from Aachen 9

Effects on Module Noise

Katja Klein

Noise of strip 512

Mean noise of APV2

• Edge strips much more sensitive due to their coupling to the bias ring

• On-chip common mode subtraction is very efficient for most strips

• More in back-up slides

Concentrate on edge strips

Status Report from Aachen 10

Peak Mode

Katja Klein

• Peak at 6-8MHz, not at 1/(250ns) = 3.2MHz, as expected from shaping time• Higher susceptibility for differential mode and 1.25V = pre-amp reference voltage• Peak position independent of injected amplitude or module position

Status Report from Aachen 11

Peak vs. Deconvolution Mode

Katja Klein

• Slight shift of peaks• Interpretation difficult

Deconvolution mode Peak mode

Status Report from Aachen 12

What about Higher Frequencies?

Katja Klein

• Cable resonances can be observed if cable length L = n/4• Two open ends (LISN 50, module ~ 2) L = /2• Cable length varied between ~ 1.1m, 1.5m, 2.1m f = 89.8MHz, 65.9MHz, 47.0MHz • Measurements above ~ 30MHz are not reliable • But no shift of peaks below 30MHz

Zoom

Status Report from Aachen 13

Influence of Pre-amp Reference Voltage

Katja Klein

connected toGround

V125

V250

VSS=GND

APV25 pre-amplifier

[Mark Raymond]

bias ring

connect toV125

[Hybrid]

strip

• Edge strips are capacitively coupled to bias ring

• Bias ring referenced to ground, pre-amp to 1.25V

• Bias ring connected to 1.25V instead of ground Susceptibility decreases drastically Pre-amp should be referenced to ground

DM, 2.5V

Status Report from Aachen 14

BCI Summary

Katja Klein

• Results are ~ consistent with measurements of Fernando Arteche (2004)

• Powerful method, but interpretation difficult (needs modelling)

• Shorter measurement time needed for faster turnaround (now ~ 1d per curve) automation of measurement with LabView is foreseen (Rüdiger)

• Will be useful to characterize susceptibility of SLHC devices (hybrids, modules, ...)

F. Arteche, measurements with TEC petal in Aachen, 2004(SLAC-PUB-11886, May 2006 )

Status Report from Aachen 15

Magnet Test

Katja Klein

• DC-DC converters must function in ~ 4T magnetic field no magnetic components

• Tests with 7T NMR-magnet at Forschungszentrum Jülich, close to Aachen

• Enpirion and CERN AMIS1 buck converters + LBNL charge pump tested (Rüdiger)- both versions with air-core and ferrite coils- 13 DC-DC converters tested in total (can show only examples here)

Status Report from Aachen 16

Magnet Test Set-up

Katja Klein

Windows-PC running LabView

PS

Scope withprobesHandle being inserted into magnet

Magnet

Handle for probes

9m long BNC cables

B field

Sourcemeter = Load

Status Report from Aachen 17

Efficiency Measurement

Katja Klein

2

out out

in in in

V IEff

V I R I

Regulated by converterValue set in sourcemeterand monitored with current probe

Set and measuredwith PS

Measured with PS Correction for cable losses

• Note: the output voltage was not measured this must be changed in the future!

• Efficiency was measured inside and outside of magnet with same set-up

• Measurement of other observables (ripple?) difficult due to long cables- what else should be measured?

Status Report from Aachen 18

Enpirion EQ5382D Buck Converter

Katja Klein

Enpirion with ferrite coilVout = 1.25V

Enpirion with air-core toroidVout = 1.25V Eff. (7T) / Eff. (0T)

Eff

icie

nc

y (

7T

) /

Eff

icie

nc

y (

0T

)

• Severe efficiency loss with ferrite inductor

• Efficiency change < 0.5% with air-core inductor

Status Report from Aachen 19

AMIS1 Buck Converter w/ Air-Core Solenoid

Katja Klein

Efficiency (7T) / Efficiency (0T)

• Efficiency changes by less than 5% with air-core inductor

• Reason for larger deviations wrt Enpirion not clear, converter stability?

• With ferrite inductor, PS went in over-current condition (back-up slides)

Status Report from Aachen 20

LBNL Charge Pump

Katja Klein

• No efficiency change for Vout = 2.5V

• For Vout = 1.25V, converter was probably not in same “state“ (stability problems)

Status Report from Aachen 21

Magnet Test Summary

Katja Klein

• No surprises:- All converters with ferrite coils showed severe efficiency loss or over-current- All converters with air-core inductors, plus charge pumps, worked without

significant efficiency loss

• We know now how to do the measurements and what to improve- Measure output voltage- Test various coil orientations

• Time needed for a measurement campaign: 2 days (but must be arranged)

• Suggest to repeat test with CERN ASIC in IHP technology and improved set-up- maybe also with AMIS2?

Status Report from Aachen 22

Future Plans

Katja Klein

• System test with strip modules of - CERN buck converter PCB with discrete components (started)- CERN AMIS1 with Bristol PCB inductors (asap)- CERN AMIS2 buck converter ASIC (summer)- CERN IHP buck converter ASIC (autumn)

• PCB development for integration of DC-DC converters into tracker structures• Automate and improve several existing test-stands (BCI, EMI, efficiency)• Set up EMI-scanner to investigate coupling mechanisms of radiated noise • Continue material budget studies• Develop specifications for buck converter• Get more practical experience with charge pumps

Status Report from Aachen 23

Summary & Conclusions

Katja Klein

• A bulk current injection test-bench for noise susceptibility studies has been set-up and first measurements have been performed

• Various DC-DC converters have been tested in a 7T magnetic field

• Both set-ups need some improvements, but seem to be useful for tests of future converter and module prototypes

• Simulation of material budget for powering/cooling schemes finished, will be presented in the next meeting

Back-up Slides

Katja Klein 24Status Report from Aachen

Status Report from Aachen 25

The APV25

Katja Klein

f = 1/(250nsec) = 3.2MHz

Status Report from Aachen 26

The APV25

Katja Klein

1.25V

2.5V

* is connected to 2.5V since about 2000

*

Status Report from Aachen 27

The APV25

Katja Klein

1.25V

2.5V

Status Report from Aachen 28

On-Chip Common Mode Subtraction

• 128 APV inverter stages powered from 2.5V via common resistor (historical reasons) mean common mode (CM) of all 128 channels is effectively subtracted on-chip

• Works fine for regular channels which see mean CM

• CM appears on open channels which see less CM than regular channels

• CM imperfectly subtracted for channels with increased noise, i.e. edge channels

Katja Klein

inverter

V125V250

VSS

V250R (external)

vIN+vCM

vCM

vOUT = -vIN

Node is common to all 128 inverters in chip

pre-amplifier

strip

Status Report from Aachen 29

Common Mode & Differential Mode

Katja Klein

Differential Mode (DM):

Common Mode (CM):

Load

LoadSource

Source

Status Report from Aachen 30

AMIS1 Buck Converter w/ Ferrite Coil

Katja Klein