Recent progress

Jamie

29th Feb 08

Shapers Samplers

• What we got

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-source

Shapers Samplers

• What we expect

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Shapers Samplers

• What if?

(sat limit means thresholds cannot be set above this value; capped)

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-source

Manual Threshold Scan

-50

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-400 -200 0 200 400 600 800

threshold (DAC codes)

Vcm=0.5v

Vcm=1.3v

To check there are no ill-effects from driving the threshold directly with the DACs, some PCB pins were lifted and the global VTH lines driven from a power supply.

(The number of hits was estimated from the typical time between ORE2 and ORE3 observed on the logic analyser)

Sensor 16 (5um epi + DPW)

DAC pins were re-attached and an automated scan performed for comparison

Threshold Behaviour

Switching point for a "Fe55" signal

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0 100 200 300 400 500 600 700 800 900 1000

Threshold (DAC units)

Sig

nal

(m

V)

reco

rded

at

swit

chin

g p

oin

t

CM=3000

CM=3500

CM=2000

Common-mode ofthresold (DAC units)

Test command: { diodeDrive 20 10 5 2600 2563 } injects a signal into the test pixel that gives a ~210mV step response, ie similar to Fe55 peak. The threshold is scanned (manually) and the output of the comparator observed with respect to the input: The value of (signal-reset) is plotted when the comparator fires.

Doesn’t show the upper range of the threshold, just how it detects a “Fe55-like” signal

Threshold BehaviourTest command: { diodeDrive 20 10 5 2600 2563 } injects a signal into the test pixel that gives a ~210mV step response, ie similar to Fe55 peak. The threshold is scanned (manually) and the output of the comparator observed (by eye) on the oscilloscope: An estimate is made of the correct operation of the comparator (a value >0% and <100% indicates noise on the comparator output)

Test pixel threshold Scan with "Fe55" signal

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20%

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60%

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100%

120%

0 200 400 600 800 1000 1200

Threshold (DAC units)

esti

mat

ed l

ikli

ho

od

of

hit

det

ecti

on

CM=3000

CM=3500

CM=2000

Common-mode ofthresold (DAC units)

Threshold Common-Mode

097 = 2048099 = 3584101 = 3072108 = 2560106 = 2048110 = 1536112 = 1024

Some different masks

106 = all active105 = alt rows masked114 = alt cols masked113 = no neighbours

Renato’s Gaussian fits

Jumper options

• J23: Substrate– GNDA (analog, default)– GNDD (digital)– NONE (floating)

• J24: VRST– VDDA1V8pix (default)– DAC

• Au BASE PLATE– Floating– Grounded

(2-3) GNDD

(1-2) GNDA

(2-3) VDAC

(1-2) VDDA

Substrate connection J23

150151 GNDD152153154 GNDA155156157 NONE158

Vrst connection J24

134135 VDDA142138140 VDAC

Base plate grounding

134135 FLOAT142153154 GNDED155