Hold signal

Variable Gain

Preamp.

VariableSlow Shaper

S&H

BipolarFast Shaper

64 Trigger outputs

Gain correction (6 bits/channel) discriminator threshold

10 bit DAC

Multiplexed charge output

MAROC : Multi-Anode Read-Out Chip

ATLAS luminometer : Roman pots

• detectors used to calibrate absolute luminosity• 10 staggered planes of 2x64 0.5 mm2 fibers

(in UV configuration with 50 µm layer offset)• 1 roman pot = 10*64 fibers in U + 10*64 fibers in V• Readout with multi-anode PMT64, Hamamatsu H7546• PM gain : 3.105 to 106

• MIP signal = 4-6 photoelectrons

Variable differentialCRRC2 shaper tp = 50-200 ns

Fast differentialCRRC shaperstp=20-200ns

Track and Hold + Widlar buffer+ 5 MHz MUX

Low offset comparator

Variable gain Preamplifier (G=0-4)

“Super common base” current conveyor

Trigger outputFast shaper :• Peaking time tp = 15ns• High gain : 3 V/pC• Noise ~ 1 mV • Pedestal spread : 2.2 mV rmsComparator :• Differential bipolar pair• Offset spread : ±1 mV• Speed < 5 ns• GTL output (0.6-1V)Trigger efficiency :• 50% trigger at 50 fC @G=1• dispersion 4fC rms• noise 1 fC• crosstalk < 1%

iin

iout

Preamplifiers“Super common base” input :• Low input impedance (~50-100Ω) (tunable)• Low bias current (20 µA)• Low noise : en = 2 nV/√HzCurrent mirror :• Scaled : 2, 1, 1/2, 1/4, 1/8, 1/16 (6 bits)• Range : 0 to ~ 4• Linearity : ± 1 %

Technology: AMS SiGe 0.35µm Chip area : 12 mm2

Package : QFP100 Power consumption : 130 mW (2mW/channel) submitted july 2005

chip requirements• 64 low impedance (100Ω) inputs • variable gain preamplifiers 0-4 to correct PM non uniformity (6 bits/channel)• 64 discriminator outputs, threshold at 0.3 p.e. (50 fC) loaded by 10 bit DAC• 1 multiplexed charge output with 20-200 ns variable shaping (max 5pC=30p.e.)

• Trigger at < 0.3 p.e. ± 0.1p.e.• Dynamic range : 11 bits : • Qmax = 5 pC, noise = 2 fC• Linearity ~ 2%• crosstalk < 1%• 200 chips to be produced in 2007

Charge outputSlow shaper :• Sallen-Key CRRC2 • Peaking time tp = 20-200 ns• Gain : 150 mV/pC (25 mV/p.e.)• 1V max output• Noise ~ 500 µV rms • Pedestal spread : 3 mV rmsTrack & Hold :• 2 pF storage capacitor• Widlar differential buffer• Readout speed : 5 MHz

preamp schematic

Pierre BARRILLON, Sylvie BLIN, , Christophe de LA TAILLE, Patrick PUZO, Nathalie SEGUIN-MOREAU

IN2P3/ LAL Orsay France

RP

IP

240m 240m

RPRP RP

RP RP RP RP

10x

MAPMTs

MA

PM

T

MA

PM

T

MA

PM

T

MA

PM

T

MA

PM

T

FE FE FE FE FE

Mother board

HV LVTTC

Trigger

Data

Substrate coupling:• Substrate resistance (~20Ω) couples mirror output to preamp ground return oscillations for ground inductance > 20nH chip on board mounting mandatory will be alleviated by substrate separation

MAROC

ASIC

64ch PM

socket

USB port

GPIB port

Control Altera

Hold signal

Photomultiplicer64 channels

Photons

Variable Gain

Preamp.

VariableSlow Shaper

20-100 ns

S&H

BipolarFast Shaper

Unipolar Fast Shaper Gain correction

64*6bits

3 discriminator

thresholds (3*12 bits)

MultiplexedAnalog charge output

LUCID

LUCID

S&H

3 DACs12 bits

80 MHz encoder

64 Wilkinson 12 bit ADC

64 trigger outputs

MultiplexedDigital charge output

MAROC2 :• substrate separation• unipolar fast shaper for counting rate up to 50MHz• 3 discriminators/ch• 80 MHz encoding• 12bit Wilkinson ADC/ch• submitted march 06

Vin=1V AC

vss1 vss2

RCd10 pF

Variable I mirrors

-200 dB

-100 dB

0 dB

Q1

SBC

Vout= 1Ω*Iout

vdd1

out_Gain

M5S1

IN

2.5V2.5V

W=32u

L=1u

M2

20 uA

Q2

W=64u

L=1u

M1

cmd0

M3 M4

vdd2

vcasc

0.750

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

0.500

0.550

0.600

0.650

0.700

temps (s)5.0E-70.0E+0 5.0E-8 1.0E-7 1.5E-7 2.0E-7 2.5E-7 3.0E-7 3.5E-7 4.0E-7 4.5E-7

Chip on baord MAROC ASICPMF board = PMT + electronics in the shadow of PM ©B. Lundberg

64 PM inputs

10 bit DAC

Chip on b64 ch multi-anode photomulitiplier

PM gain dispersionNon uniformity : 1 to 3

Trigger efficiency vs channel number (“s curves”)

50% trigger efficiency vs channel number (G=1) average = 50 fC = 1/3 phtoelectron

Crosstalk : up to 10 pC injected in channel 34, trigger at 50 fC, 2 direct neighbours trigeer at >

Trigger efficiency for different preamp gains

Signal waveforms for different preamp gains Linearity vs preamp gain (0 to 4)

Output waveforms for 0 to 5 pC input

Pedestal dispersion

Substrateresistance

10 bit DAC for commonthreshold

MAROC Chip-On-Board testboard

Roman pots with scintillating fibers for luminosity measurement ©CERN

Readout electronics mounted on roman pots : 5x5 PM array ©CERN, Lund

Substrate coupling modelization in preamp groundSynoptic diagramm of MAROC2 chip