Gossipo-3: a prototype of a Front-end Pixel Chip for Read-out of Micro-Pattern Gas Detectors. TWEPP-09, Paris, France. September 22, 2009. Christoph Brezina

Gossipo-3: a prototype of a Front-end Pixel Chip for Read-out of Micro-

Pattern Gas Detectors.

TWEPP-09, Paris, France. September 22, 2009.

Christoph Brezina2, Klaus Desch2 , Harry van der Graaf 1, Vladimir Gromov 1 , Ruud Kluit 1, Andre Kruth2, Francesco

Zappon1

1 National Institute for Subatomic Physics (Nikhef), Amsterdam,2 Institute of Physics, Bonn University

Vladimir Gromov

TWEPP-09 V.Gromov 222/09/09

Outline

Read-out of Micro-pattern gas detectors

Gossipo-3 prototype: functionality and

features

Design and performance of basic circuits

Plans and perspectives


Micro-pattern gas detectors: layout and features

- particle track image (projection)- particle track image (projection)- 3D track reconstruction3D track reconstruction- no sensor leakage current compensation- low parasitic capacitance (less than 10fF)- micro-discharges in avalanche gap

Cluster3

Cathode (drift) plane

Gas Amplification Structure

Cluster2 Cluster1

Readout chip

1mm …1m → Drift gap

400V50um → Avalanche gap

Gas-avalanche detector combining a gas layer as signal generator with a CMOS readout pixel array

Front-endcircuit

Cpar


Readout Chip for MPGDs

2007: GOSSIPO-2 - technology: 0.13μm CMOS- array: 16 x 16, 256 pixels- pixel: 55 um x 55 um - active area: 0.88mm2 - event clock: 40MHz- high resolution TDC-per-pixel architecture (bin=1.8 ns)- range: 350ns (4-bits @ 25ns) 2009: GOSSIPO-3 / GOSSIPO-4- technology: 0.13μm CMOS- array: 32 x 32, 1024 pixels- pixel: 60μm x 60μm - active area: 3mm2

- event clock: 40MHz- accuracy (bin size): 1.73ns- range: 102μs (12-bits @ 25ns)- ToT accuracy: σ = 200e- (27ns)- ToT range: 6.4μs (8-bits @25ns)- Hit Counting mode- noise: σ = 70e-

- fast response: 20ns (rise time)- power (goal): 100mW/cm2 (3μW/ch)

GOSSIPO-2

GOSSIPO-3

GOSSIPO-4


Gossipo-3: MPW prototype

FeaturesFeatures each pixel measures: - hit arrival time → cluster’s drift time - time-over-threshold → charge deposit

- number of hit (24 bits) triggering options: - external common stop read-out options: - serial read-out of all the pixels

other functionalities: - auto clear (no stop signal after expected latency) - INGRID & pixel analog signal monitors

Time modeTime mode

Hit Counting modeHit Counting mode


TDC with local oscillator

Hit signal

Local oscillator output (Ffast = 640MHz)

Sta

rt

Sto

p

Clock signal (Fslow = 40MHz).

Trigger signal

Sto

p

Nslow

Nfast

Time = Nslow / freqslow + Nfast

/freqfast

StartStop

Local oscillator

Pixel_1

Hit

40MHz Clock Bus

Out

Power ≈ Hit_Rate ● 6 μW / MHz per channel → 0.16 μW @ 27.2KHz


Gossipo-3: the pixel

Layout of the pixel

LFSR = Counters (data taking) orLFSR = Shift registers (data read-out)

Control signals- Clock - TRIGGER (common stop)- TOKEN - RESET

controlcontrol

Localfast

oscillator(600MHz)

Localfast

oscillator(600MHz)

4 bit Fast counter

4 bit Fast counter

8 bit ToT counter8 bit ToT counter

12 bit Slow counter

12 bit Slow counter

6 bit Pixel configuration

Memory

6 bit Pixel configuration

Memory

Threshold DAC

Threshold DAC

pad

-Threshold - Mask Time /

Counting

HIT

Block diagram of the pixel

oscillator

Logic: counters & control

Preamp & comparator

DA

C


Diagrams (TIME mode)

Preamp_out

Hit (asynchronous)

Clock (40MHz)

Counter Fast

Counter ToT

Trigger

Counter Slow

Token

Reset

Data taking phase (LFSR = Counter)Data read-out Phase (LFSR = Shift Registers)

ToT

State diagram


Local oscillator :basic limitations

NANDENOUT

Delay = Tfast/2 = Function (Temp, Vdd)

EN

Tfast (1.72 ns)

OUT

1.05 1.1 1.15 1.2 1.25 1.31.6

1.7

1.8

1.9

2

2.1

2.2

0 20 40 60 80 1001.7

1.8

1.9

2

2.1

2.2

- 12% / 100mV 2% / 1

0 ◦ C

Channel-to-channel statistical spread is 4%

VDD effect TEMP effect

0ns…Tslow (25 ns)

0…15 (4-bit TDC)

2.2

2.1

2

1.9

1.8

1.7

1.61.05 1.1 1.15 1.2 1.25 1.3

Power supply voltage, Volts0 20 40 60 80 100

2.2

2.1

2

1.9

1.8

1.7

Temperature, ◦C

Tfast ,ns

Tfast ,ns

TWEPP-09 V.Gromov 1

022/09/09

Local oscillator : reproducibility

∆tmax = 0.5ns (accumulated)

Pixel-to-pixel mismatch Pixel-to-pixel mismatch

σ(∆Tfast/Tfast) ≈ 2% ● (N●W ● L)-0.5

Monte Carlo simulationsMonte Carlo simulations..

vdd_osc Nominal situation

Upper limit Low limit

0.61 V 1.72 ns0.76 V 1.73 ns 1.13 ns 2.26ns

1.1 V 1.72 ns

Tfast=1.73ns

Process variation Process variation

clock period =25ns

TWEPP-09 V.Gromov 1

122/09/09

Local oscillator: frequency tunability

Opamp

Off-chip cap10μF

4bit DAC

Bandgap CurrentReference with Temp. Gradient

vdd=1.2V

1.14k2k

U vdd_osc =0.6V…1.1V

FunctionalityFunctionality- tunes oscillation frequency - power supply ripple rejection- temperature compensation

Common on-chip LDO: voltage regulator Common on-chip LDO: voltage regulator

Uref

TWEPP-09 V.Gromov 1

222/09/09

The front-end

Time

Uin

Uin + 70mV

Uin + Qin / Cfb

-Time●Isat Tfb/Cfb

exp[-Time/(Cfb●RonTfb )]

Uout

Tfb in saturation Tfb in triode

FeaturesFeatures- low time jitter, time walk- constant current feedback (1nA) - high gain (1mV / fF)

Uout

170fF

To CompCpar ≈ 10 fF

Tfb

Cfb =Cds+Cdg+Cdb+Cdj ≈ 1 fF

Input pad (22μm x 22μm)

OPAMPDischarge protection

Ib = 6nA2.4/2.4

0.48/2.4

TWEPP-09 V.Gromov 1

322/09/09

The front-end circuit

Main specifications:Main specifications:- low power consumption (3μW/ch)- fast response (20ns)- low noise (σ =70 e-)- channel-to-channel threshold spread

(σ =70e- no equalization)(σ = 5e- with equalization)

Vdd_ana

Input stage

720 nA

Ron = 30MΩ

0.48/2.4

Uout_preamp

435 nA70 nA

2.4/2.4

Preamp_in

1fFCpar ≈ 10 fF

6 nA

Voltagefollower

Feedback

gm=23u

C*= 6f

Tfb

sub_preamp (0.2V)

5/0.24

2nA UTHR_common

Vdd_ana

2.4/2.4

0.48/2.4

UTHR_pixel

Discr.

Baseline recovery

Uout_comp

ncapC=170fF

Ron = 100MΩ

TWEPP-09 V.Gromov 1

422/09/09

Time-over-threshold measurements

Uout

charging

discha

rging

0 5000 1 104

1.5 104

2 104

2.5 104

3 104

0

1000

2000

3000

4000

Qin, e-

ToT,ns

Qm

ax =

28

00

0e

-

0.13ns / e-

Time, sec

Cpar =10fF

Cfb= 1fF

OPAMP

Ib = 1nA

Qin

Qin=400e-…

28000e-

FeaturesFeatures- wide dynamic range (up to 28ke-)- resolution σ = 200e- (27ns)- poor channel-to-channel uniformity (spread is 20%)

ToT

threshold

0 1μ 2μ 3μ 4μ 5μ

0.4

0.3

0.2

0.1

0

Uout,V

TWEPP-09 V.Gromov 1

522/09/09

Discharge protection

CSP = 20fF

SiNProt (7μm thick)

InGrid

Qdis = UHV●CSP = 8pC

UHV = - 400V

High resistive protection layer

CGR= 25pF

InGrid UHV = - 400V

Read-out chip 1.4cm x 1.4cm

Qdis = UHV●CGR = 10 000pC

Read-out chip 1.4cm x 1.4cm

NO protection NO protection layerlayer

With protection layerWith protection layer

QdisQdis

SiNProt layer limits the size the discharge

50μm

TWEPP-09 V.Gromov 1

622/09/09

Protection device: Qdis = 8pC

n+ n+

P-well

in_preamp (Udc=+0.424V)

GND

Standard NFET (W=1μm, L=0.24 μm)

Uin_preamp

No protection

With protection

← -1V (no damage of the MOSFET’s)

← -7.5V (the MOSFET’s will be damaged)

IMOS_channel

p+

GND

Idioden-type inversion layer

FeaturesFeatures- small area (W=1μm, L=0.24μm) - low parasitic capacitance (1.3fF)- negligible leakage current (250pA)

TWEPP-09 V.Gromov 1

722/09/09

Conclusions

Gossipo-3 is a prototype of a Front-end Pixel Chip (0.13μm CMOS technology) for Read-out of Micro-Pattern Gas Detectors.

Every pixel is equipped a high resolution TDC (1.7ns) covering dynamic range up to 100us and a ToT counter to evaluate the charge deposit.

The chip can also operate in hit counting mode.

Gossipo-3 is taped-out for MPW production run (September 21).

Documents

Gossipo-3: a prototype of a Front-end Pixel Chip for Read-out of Micro-Pattern Gas Detectors. TWEPP-09, Paris, France. September 22, 2009. Christoph Brezina