First look at digital module testing at UIC

Susan Dittmer, Titas Roy

RD53A testing meeting, 13/05/19

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S. Dittmer RD53A testing meeting, 13/05/19

• In February we got the first module from ETH, Zurich.

• This module is referred to as S3 and has four RD53A chips without any sensor.

• We used the new multichip readout feature in the Yarr firmware to verify some basic tests that ETH had performed using bdaq.

• We will be showing some preliminary results of S3.

Outline

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coldboxcomputer with Yarr FPGA, and tools to

control coldbox

adaptor card 4 ROCs

display port to communicate with ROCs

S. Dittmer RD53A testing meeting, 13/05/19 3

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2input I (A)

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digitalanalog

S3:IV curve

LV IV curve at supply• Varied the input current source (as measured on the PS) and plotted the corresponding analog

and digital voltages as measured at the supply

• Need probe station to measure IV curves for individual ROCs

• The turn on point is lower than what ETH had reported.

S. Dittmer RD53A testing meeting, 13/05/19 4

Module S3

ROC1 100

ROC0 101

ROC3 111

ROC2 110

• Each chip has three wirebond connections determining the chipID (4-7)

• ROC0 (chipID 5) does not turn on (same as reported by ETH)

• ROC1 (chipID 4) connected to Rx1

• ROC2 (connected to Rx 2) seems to have lost the connection on the MSB and responds to chipID 2 instead of chipID 6

• ROC3 (chipID 7) connected to Rx3

• We are reading out all four chips through one display port on the adaptor card

S. Dittmer RD53A testing meeting, 13/05/19

• Looking at the response of 3 out of 4 chips to a digital scan

• ROC0 did not turn on at ETH and we didn’t get a response either.

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Digital scan

Occupancy Maps of the 3 chips: we expect ~100 hits

ROC1 ROC2 ROC3

SYNC LINEAR DIFF

S. Dittmer RD53A testing meeting, 13/05/19 6

Analog scan

• ROC1 and 2 show that all pixels are enabled during an analog scan

• ROC3 does not turn on (also as reported by ETH)

ROC1 ROC2 ROC3

S. Dittmer RD53A testing meeting, 13/05/19 7

Threshold and ToT Tuning

• Multi-ROC tuning in Yarr

• ROCs tuned in parallel — same time to tune module as single ROC

• Iterative tunings continue until both ROCs reach target, allowing for different settings per ROC

• Target values still same for all ROCs

• Threshold tuning

• First, attempt to tune all FEs to uniform threshold

• Next, attempt to tune each FE to lowest stable threshold

• ToT tuning

• Target ToT 8 for 12000 e- (MIP charge)

• Tune ToT for differential FE; check difference between good and bad pixel results

S. Dittmer RD53A testing meeting, 13/05/19

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Threshold scan, uniform threshold

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Analog FEsSynchronousLinearDifferential

RD53A Internal Chip SN: JohnDoeRD53A Internal Chip SN: JohnDoe = 1895.3histMean = 146.3histRMS

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RD53A Internal Chip SN: JohnDoeRD53A Internal Chip SN: JohnDoe = 2010.6histMean = 161.2histRMS

Sync FE: threshold ~1800e-, 897 untuned pixels Lin FE: threshold ~1900e-, 11 untuned pixels Diff FE: threshold ~1000e-, 195 untuned pixels

Sync FE: threshold ~2000e- , 258 untuned pixels Lin FE: threshold ~2000e-, 22 untuned pixels Diff FE: threshold ~2000e-, 302 untuned pixels

One pixel per 8x8 core

enabled for each scan iteration

Lost communication

after 52nd iteration -- no

data for 18.75% of

pixels

Chip SN: ROC1

Chip SN: ROC1

Chip SN: ROC2

Chip SN: ROC2

S. Dittmer RD53A testing meeting, 13/05/19 9

Threshold scan, lowest threshold

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RD53A Internal Chip SN: JohnDoeRD53A Internal Chip SN: JohnDoe = 861.9histMean = 323.8histRMS

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RD53A Internal Chip SN: JohnDoeRD53A Internal Chip SN: JohnDoe = 816.3histMean = 387.3histRMS

Linear FE should probably operate

at higher threshold —

large number of untuned pixels

Sync FE performance very poor for ROC2 — can

threshold dispersion be

improved?

Sync FE: threshold ~1300e-, 540 untuned pixels Lin FE: threshold ~750e-, 2207 untuned pixels Diff FE: threshold ~600e-, 779 untuned pixels

Sync FE: threshold ~1500e- , 14582 untuned pixels Lin FE: threshold ~800e-, 9596 untuned pixels Diff FE: threshold ~600e-, 3695 untuned pixels

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Chip SN: ROC1

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Chip SN: ROC2

S. Dittmer RD53A testing meeting, 13/05/19 10

ToT for 12000 electrons (targeting 8)

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Mean ToT [bc]

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RD53A Internal Chip SN: JohnDoe

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RD53A Internal Chip SN: JohnDoe

Pixels with unmeasurable

threshold in linear FE also have

unmeasurable ToT

Settings not optimal for bad

pixels in differential FE (as

expected)

Sync FE: ToT ~7.3 Lin FE: ToT ~7.8Diff FE: ToT ~8.2

Sync FE: ToT ~7.1Lin FE: ToT ~7.2Diff FE: ToT ~8.5

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RD53A Internal Chip SN: JohnDoe

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Chip SN: ROC2

S. Dittmer RD53A testing meeting, 13/05/19 11

Improving Sync FE threshold for ROC2

• From sync FE manual: threshold dispersion can be improved at price of higher power consumption (by adjusting IBIAS_DISC_SYNC)

• Maybe we are already power limited?

• Had been running at 1.8A ISupply — seemed to give most stable operation

• Increase current to 2.0A and redo threshold scan at same settings

S. Dittmer RD53A testing meeting, 13/05/19

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Redoing Threshold Scan at 2.0A

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RD53A Internal Chip SN: JohnDoeRD53A Internal Chip SN: JohnDoe = 852.6histMean = 279.3histRMS

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RD53A Internal Chip SN: JohnDoeRD53A Internal Chip SN: JohnDoe = 1107.4histMean = 504.1histRMS

Much better performance for

sync FE in ROC2; slightly better performance

even for ROC1

Also slightly better

performance for lin FE in ROC2

Sync FE: threshold ~1200e-, 145 untuned pixels Lin FE: threshold ~800e-, 2199 untuned pixels Diff FE: threshold ~600e-, 777 untuned pixels

Sync FE: threshold ~1700e- , 81 untuned pixels Lin FE: threshold ~900e-, 7808 untuned pixels Diff FE: threshold ~600e-, 3398 untuned pixels

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Chip SN: ROC2

S. Dittmer RD53A testing meeting, 13/05/19 13

Summary• Received digital module from ETH; confirmed no changes to functionality

• 3/4 ROCs active in digital scan; 2/4 in analog

• Need probe station to confirm IV curves for each ROC

• Reasonable success at tuning threshold and ToT of two active chips

• Issues observed during tuning

• Occasional loss of communication during longer scans

• Sync FE needs full power budget to operate stably at low threshold

• Next: measure individual IV curves for each ROC to check if we are working in the optimum current range

• Need a needle probe station / training to operate

• Not related to modules, but we want to be able to get the sync FE working with external trigger for the upcoming testbeam at Fermilab—any help/suggestion in this regard will be much appreciated.