Analog front-end chip for GEM detectors

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ANALOG FRONT-END CHIP FOR GEM DETECTORS

E. Atkin, E. Malankin, V. ShumikhinNRNU MEPhI, Moscow

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OUTLINE

GEM Chip structure Channels structure Test benches Experimental data Summary

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GEM DETECTORS

Cross-section of a triple GEM detector

P. Abbon et al. / NIM (2007) 455–518

~50 µm

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CBM

Muon system of the international CBM experiment, being designed on the new accelerator facilities at FAIR GSI (Darmstadt, Germany), built on the base of the gaseous detector of high resolution. Muon System consists of about 1 million channels. For the Muon System signals read-out ASIC application is neccesary.

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CBM

Muon system of the international CBM experiment, being designed on the new accelerator facilities at FAIR GSI (Darmstadt, Germany), built on the base of the gaseous detector of high resolution. Muon System consists of about 1 million channels. For the Muon System signals read-out ASIC application is neccesary.

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CBM

Muon system of the international CBM experiment, being designed on the new accelerator facilities at FAIR GSI (Darmstadt, Germany), built on the base of the gaseous detector of high resolution. Muon System consists of about 1 million channels. For the Muon System signals read-out ASIC application is neccesary.

~1 million channels

↓~15 000 ASICs x

64 ch.

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CBM

Muon system of the international CBM experiment, being designed on the new accelerator facilities at FAIR GSI (Darmstadt, Germany), built on the base of the gaseous detector of high resolution. Muon System consists of about 1 million channels. For the Muon System signals read-out ASIC application is neccesary.

~1 million channels

↓~15 000 ASICs x

64 ch.

Front-end forMUCH

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SPECIFICATIONS Input signal range of 1.5-100 fC Charge polarity – negative ENC – less than 0.3 fC Detector capacitance up to 100 pF Maximum hit rate/channel – 2 MHz Power consumption – 2 mW/ch

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CHIP STRUCTURE

1.5 CSA + stand alone Shaper channels (Preamp ver. 1)

2.5 CSA channel with built-in shaping (Preamp ver. 2)

3.OpAmp block4.Digital test

structures

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CHANNEL STRUCTUREPREAMP VER.1

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CSA CORE

• Input transistor – nMOS (7mm * 360 nm) • Common source stage• Folded boost current amplifier • Output source follower

Feedback: gain setting cap + discharge transistor to set the maximum hit rate of channel not less than 2 MHz

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SHAPER

Noninverting 2nd order

Sallen-Key filter

The shaper has two additional adjustments:- TAIL – tail cancellation- SH_BL – baseline tuning

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PREAMPVER.2

• Input transistor – nMOS (4mm * 360 nm) • Common source stage• Folded boost current amplifier • Output source follower

Feedback: gain setting cap + discharge resistor to set the maximum hit rate of channel not less than 2 MHz

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CHIP LAYOUT

• CLCC68 Package• Die–1525 x 1525 μm2

• UMC 180 nm CMOS MMRF process• 2012 run of Europractice

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TESTBOARD

CLCC Socket

LDO regulato

r

1 pF capacita

nceDetector capacita

nce emulatio

n

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TESTBOARD

CLCC Socket

LDO regulato

r

1 pF capacita

nceDetector capacita

nce emulatio

n

Reference potentiome

ters

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OUTPUT RESPONSES (VER.1)Input charge swept from 25 to 70 fC

CSA CSA & Shaper

Shaper

CSA

Voltage pulser

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TRANSFER FUNCTION (VER.1)• Dynamic range – 1.5 – 100 fC• Integral nolinearity ~ 4%

ShaperChannel gain ~ 6

mV/fC

CSACSA gain ~ 2.5

mV/fC

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RMS NOISE MEASURMENTS (VER.1)

Aim: Cin >> Cdet

Estimation: CSA open-loop gain ≥ 1400

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CSA OUTPUT RESPONSE & TRANSFER FUNCTIONVER.2

transfer functionCSA gain ~ 5 mV/fCCSA output

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NOISE ESTIMATION

PreAmp (ver. 1)ENC – 875е Cdet = 1p 2427e Cdet = 100p

PreAmp (ver. 2)ENC – 1070е Cdet = 1p 2500e Cdet = 100p

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TESTBOARD WITH GEM*

Socket with Chip

GEM Anode

Pad area 5x5 mm2

Pad capacitance 12 pF

Gas chamber

with Ar/CO2 *Testboard designed by PNPI

team

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TESTS WITH 55FE SOURCE*

55 Fe amplitude spectrum, obtained

by the preamplifier & GEM.

*tests provided by PNPI team

Preamplifier output

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SUMMARY Designed and prototyped 2 versions of read-out with preliminary CBM MUCH specifications:

Preamplifier (ver.1)

Preamplifier (ver. 2)

Gain 6 mV/fC; 5 mV/fCInput signal range

1.5-100 fC; 1.5-100 fC;

Maximum channel rate

2 MHz 2 MHz

Power consumption

1.2 mW/channel 2 mW/channel

ENC Cdet = 1p Cdet = 100p

875е 2427e

1070е2500e

Area on chip 1050 x 100 µm 200 x 100 µm

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THANKS FOR YOUR ATTENTION...