MultiAnode Readout Chip for MaPMTs

1
Multi-Anode Readout Chip for MaPMTs
P. Barrillon, S. Blin, M. Bouchel, T. Caceres, C.
de La Taille, G. Martin, P. Puzo, N.
Seguin-Moreau IN2P3/LAL Orsay,France

• Description
• Requirements
• Performances
• Future

Session N23 HEO NP Instrumentation IV New
Detection Techniques
2
ATLAS Luminometer

• Absolute measurement of the luminosity
• Roman Pots
• 0.5mm2 scintillating fibers
• 1 RP 1064 fibers in U 1064 fibers in V
• 240m from the Interaction Point
• Multi Anode PM Tubes
• 64ch Hamamatsu H7546
• HV 800-950 V
• Gain 3.105-106
• Maximal signal 4-6 photoelectrons
• 1-3 non uniformity
• 200 readout chips needed (to be produced in 2007)
• See S. Ask talk (N29-1)

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MAROC Main Features

• Multiplexed charge output
• Track Hold
• 2pF storage capacitor
• 5MHz readout speed
• Widlar differential buffer

• Technology AMS SiGe 0.35 mm
• Package CQFP240
• Power consumption 130mW
• 2mW/ch
• Area 12 mm2
• Submitted June 05
• Received November 05

Hold signal

Variable Slow Shaper CRRC2 tp 50-200ns
Multiplexed Charge output

SH




Photons
64 inputs
Bipolar Fast Shaper CRRC tp 20-200ns
Variable Gain Preamp.
64 trigger outputs
Photomultiplicator

• Variable gain preamplifier
• Super common base inputs
• Low impedance (50-100 ?) tunable
• Low bias current (20mA)
• Low noise

discriminator threshold 10 bits DAC


Gain correction 6 bits/channel

• 64 discriminator outputs
• Threshold set thanks to a 10 bits DAC

4
MAROC - Requirements
GPIB port

• Variable gain preamplifier 0-4 to correct PM non
  uniformity
• Trigger at 1/3 p.e ( 50fC)
• Qmax 5pC (30 p.e)
• Noise 2fC
• Linearity 2
• Cross talk lt 1

Control Altera
64ch PM socket
MAROC (COB)
USB port
Test board

• Characterisation tests performed in lab

5
Substrate Coupling
Nmos mirror

• Substrate resistance (20 ?) couples mirror
  output to the preamplifier ground return
• Connections between the ground of the chip and
  the test board ground are quite long (Lbonding
  Lpackage Lsocket 30 nH)
• Oscillations (100MHz) for ground inductance gt
  20nH when all channels are set at high gain
• Chip on board mounting mandatory ? no package and
  ground plan under the chip
• Next generation chip should have substrate
  separation

SBC PA
R
vss1
vss2
Lbonding Lpackage
Chip with socket
Chip on board
6
Slow Shaper Charge Output

• Waveforms taken for different preamplifier gains
  with fixed input charge Qinj 1pC
• Linearity vs gain 1
• Waveforms vs Qinj with all channels set at G1
• Linearity vs Qinj (0-5pC) 2
• Preamp gain G1
• 150 mV/pC
• 24 mV/pe _at_ 106
• Noise 500 mV
• Max output 1 V
• Pedestal spread 3mV rms

? G1
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Threshold - DAC Linearity

• Thermometer
• 4 bits DAC
• coarse tuning
• 200 mV/bit
• Mirror
• 6 bits DAC
• fine tuning
• 3 mV/bit
• Linearity /- 2

8
S-curves

• Input charge scan with fixed threshold
• Trigger efficiency 100 around 50fC as requested
• Nice spread of 50 trigger efficiency point
  3.9fC rms
• Noise 1fC

S-curves vs gain
9
Crosstalk

• Central channel fed with signal up to 10pC
  triggers at 50 fC
• Neighboring channels do not trigger before 7.5pC
• Cross Talk lt 1 as required

10
Gain equalization

• Lab tests performed before test beam
• Light produced by a LED
• System equipped with a PM
• Tuning of the gain channel by channel allowed
  equalization of the response

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Conclusions - what next ?

• First version of MAROC has showed nice
  performances despite the substrate coupling
  problem
• It has been used during test beam at CERN (oct
  06) with success
• Next version of MAROC is tested in lab and shows
  convincing performances

BOTTOM side
Chip On Board
Detector used during test beam
10x2x16 fibers
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Next version MAROC2
Hold signal

Multiplexed Analog charge output
Variable Slow Shaper 20-100 ns

SH


SH
Photons

64 Wilkinson 12 bit ADC
Multiplexed Digital charge output
64 inputs
Variable Gain Preamp.
Bipolar Fast Shaper
Photomultiplier 64 channels











80 MHz encoder
Unipolar Fast Shaper
Gain correction 646bits
64 trigger outputs



3 DACs 12 bits
3 discri thresholds (312 bits)
LUCID

• Substrate separation
• Unipolar fast shaper
• 3 discriminators
• 80MHz encoding
• 12bits Wilkinson ADC

New features