Chips developed at CERN in the framework of the Medipix3 Collaboration

CHIPS DEVELOPED AT CERN IN THE FRAMEWORK OF THE MEDIPIX3

COLLABORATION

R. Ballabriga, J. Alozy, M. Campbell, E. Frojdh, M. De Gaspari, E.H.M. Heijne, S. Kulis, X. Llopart, T. Poikela, L.Tlustos, P. Valerio and W.Wong

CERN, PH Department

1211 Geneva 23

Switzerland

-2- 2

• Hybrid pixel detector• Possible radiation measurements

on-pixel• Readout architecture

-3- 3

Hybrid pixel detector illustration

• The detector can be optimized for the application• Standard CMOS process

-4- 4

Thr

time

vOUTpreamp

Photon Counting (PC)N hits/pixel/unit time (imaging)

Time of Arrival (ToA) (relative to Shutter end)T time (time measurement. Allows correlation between events, event-BX, 3D reconstruction in gas detectors)

Time over Threshold (ToT)Q Charge/hit (deposited charge measurement in sparse frames, allows subpixel spatial resolution)

Possible on-pixel radiation measurements

Time of Arrival (ToA) (latching the time variable into a register)

t0 t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t13 t14

latch t1

CF

-AV Sh

Thr

Disc Out Digital circuitry

vOUTpreamp

PreamplifierShaper Comparator Digital pulse

processing circuitry

-5- 5

Readout time vs frame occupancy for different readout architectures

Simulation with 100MHz clock, 256x256 pixel matrix, 16 bits/pixel, randomly distributed hits.Full Frame Readout: 256x256x16 bits are read out.Event-by-event (zero suppressed): for each pixel hit, we read out 16bits for the content and 16 bits for the pixel address.Zero compression: columns and pixels that did not register events are skipped.

20%5%1%0.1%

X. Llopartcompression

-6- 6

Medipix1 (1998)

Medipix2 (2001)

Timepix (2006)

Medipix3 (2009)

Dosepix (2011)

Timepix3 (2013)

Velopix

Clicpix prototype (2013)

1mm SACMOS

0.25mm CMOS

0.13mm CMOS

65nm CMOS

Medipix related hybrid pixel readout chips

Smallpix

M. De Gaspari: “Design of the analog front end for the timepix3 detector and smallpix hybrid pixel detectors in 130nm CMOS technology”

T. Poikela “Digital column readout architectures for hybrid pixel detector readout chips”

P. Valerio: “A prototype hybrid detector pixel ASIC for a CLIC experiment”

Covered in detailLessons learnt from Medipix3.0

-7- 7

Medipix1 (1998)

Medipix2 (2001)

Timepix (2006)

Medipix3 (2009)

Dosepix (2011)

Timepix3 (2013)

Velopix


1mm SACMOS, 64x64 pixels, 170x170mm2

PC / Frame based readout

0.25mm CMOS, 256x256 pixels, 55x55mm2



PC, ToT, ToA / Frame based readout


PC / Frame based readout Event by event charge reconstruction and allocation


ToT, PC / Rolling shutter (programmable column readout)Event by event binning of energy spectra (16 digital thrs)


PC; ToT, ToA (simultaneous)/ Data driven readout

0.13mm CMOS, 256x256 pixels, 55x55mm2, ToA, Binary/ToT (TBD), Data driven readout

65nm CMOS, 64x64 pixels, 25x25mm2

ToA, ToT1 (simultaneous)/ Frame based (ZC)

Smallpix0.13mm CMOS, 512x512 pixels, 40x40mm2 (TBD), TSV compatiblePC, iToT; ToA, ToT1 (simultaneous)/ Frame based (ZC)


-8- 8

Motivation for the Medipix3

-9- 9

Cross section of a Hybrid Pixel Detector system (X-ray photon energy deposition)

n-well

gm

Iin Vout

n-well

gm

Iin Vout

n-well

p-substrate gm

Iin Vout

n-well

gm

Iin Vout

p+ p+ p+ p+

HV

Sensor dimensions to scale (55mm pixel pitch, 300mm thick sensor)

g gA. B.

A. The signal from a photon is induced in one pixel

B. The signal for one photon is shared between two pixels if the photon deposits its energy at the pixel edges

-10- 10

2 4 6 8 10 12 140

1

2

3

4

5

6

7x 10

- 3 Si, 55m square x 300m, 10 keV

energy [keV]

[au

]

single pixel 100e- • Simulated Data

• Si 300mm, 55mm pixel

• 10keV monochromatic photon beam

• Charge diffusion produces “charge sharing” tail

Motivation for the Medipix3 chip

Simulation: L. Tlustos

-11- 11

Absorption efficiency for Si

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

Abso

rptio

n effi

cien

cy [%

]

Photon Energy [KeV]

Absorption efficiency 300um Si

-12- 12

Absorption efficiency for Si

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

Abso

rptio

n effi

cien

cy [%

]

Photon Energy [KeV]


Absorption efficiency 1mm Si

-13- 13

Absorption efficiency for Si is low in the energy range for diagnostic radiography

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

Abso

rptio

n effi

cien

cy [%

]

Photon Energy [KeV]



Energy range for diagnostic radiography

-14- 14

The absorption efficiency depends on Z

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

Abso

rptio

n effi

cien

cy [%

]

Photon Energy [KeV]



Absorption efficiency 300um GaAs


-15- 15


0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

Abso

rptio

n effi

cien

cy [%

]

Photon Energy [KeV]



Absorption efficiency 300um CdTe



-16- 16


0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

Abso

rptio

n effi

cien

cy [%

]

Photon Energy [KeV]



Absorption efficiency 300um CdTe


Absorption efficiency 2mm CdTe


-17- 17

n-well

gm

Iin Vout

n-well

gm

Iin Vout

n-well

p-substrate gm

Iin Vout

n-well

gm

Iin Vout

p+ p+ p+ p+

HV

Fluorescence in high-Z materials

ggf

1. Primary photon releases photoelectron that loses its energy generating electron-hole pairs

2. De-excitation of the first atom releases a characteristic photon that will deposit its energy some distance away from the first interaction

3. Multiple hits can be detected for a single incoming photon

1. 2.

3.

-18- 18

Fluorescence yield [%]Mean free path of fluorescence photon [mm]

Energy fluorescence photons [keV]

Z

Table: L. Tlustos, PhD thesis

Fluorescence in high-Z materials

The mean free path of the fluorescence photons is in the same order of magnitude as the pixel pitchThe fluorescence yield increases with the atomic number

-19- 19

Motivation for the Medipix3 chip

• Simulated data

• CdTe 300mm

• 110mm pixel pitch

• 40keV monochromatic beam

• The influence of fluorescence photons in the energy spectrum is seen

Simulation: L. Tlustos

5 10 15 20 25 30 35 40 450

0.5

1

1.5

2

2.5

3

3.5

4x 10

-3 CdTe, 110m square x 300m, 40 keV

energy [keV]

[au

]

single pixel 100e-

2x2 summing 200e-

-20- 20

Architecture for the Medipix3

-21- 21

1. TH0 is applied to the local signal

2. Arbitration circuitry identifies the pixel with largest charge and supresses the pixels with lower signal

4. The pixel with highest charge checks the adjacent summing circuits to see if at least one of them exceeds TH1

3. In parallel, the charge has been reconstructed in the analog summing circuits

The algorithm for charge reconstruction and hit allocation: Charge Summing Mode

Advantage of small pixels without disadvantage of charge sharing

-22- 22

gm-Av

CF

THspm

TestPulse

TestBit

DiscOutLocal

CTEST

8

THcsm

DiscOutSum

Arbitration logic

DiscOutNeighbours

1 Counter0

Counter1

1

DataOut0 DataOut1

1

DataIn1DataIn0

1 1

1

1

synchronization

1

If((LocalCharge>ChargeNeighbours) and (Reconstructed charge in one of the adjacent summing circuits > THCSM))Then Counter1++

Local charge

Reconstructed charge

Charge from adjacent pixels

1

3

1

3

DiscOutSumNeighbours

Local charge to adjacent pixels

If(LocalCharge>ChargeNeighbours) Then Counter0++

3

1

ToNeighbours

8

Single Pixel Mode Arbitrated

Charge Summing Mode

Medipix3RX Pixel Diagram: Charge Summing Mode

-23- 23

Linearity Noise Th dispersion

Medipix3RX Modes of Operation

System Configuration Pixel Operating Modes # Thresholds

Fine Pitch Mode → 55 µm x 55 µm Single Pixel Mode 2

Charge Summing Mode 1+1

Spectroscopic Mode → 110 µm x 110 µmSingle Cluster Mode 8

Charge Summing Mode 4+4

Front-end Gain Modes Linearity (5% dev) # Thresholds

Super High Gain Mode ~7.5 ke-

2High Gain Mode ~14 ke-

Low Gain Mode ~17.5 ke-

Super Low Gain Mode ~22 ke-

Pixel Counter Modes Dynamic range # Counters

1-bit 1 2

6-bit 63 2

12-bit 4095 2

24-bit 16777215 1

Pixel Readout Modes # Active Counters Dead Time

Sequential Count-Read (SCR) 2 Yes

Continuous Count-Read (CCR) 1 No

-24- 24

A1 to A4: analog circuitry of pixels 1 to 4 respectively

D12: digital part of pixels 1-2

D34: digital part of pixels 3-4

Digital part designed using standard digital flow using a high density - low power transistors library

Medipix3RX regular structure layout

A1

110mA2

A3

A4

D12D34

110mm

-25- 25

Measurements Medipix3RX

-26- 26

Measurement of 10KeV monochromatic light

Derivative of the total number of counts in the matrix as a function of the thresholdFull matrix measurement, Raw data, No offline pixel realignment In Charge Summing Mode the energy is reconstructed and each photon is counted once

E. Fröjdh

-27- 27

Measurement (60keV, 110mm pitch, 2mm CdTe)

T. Koenig

~4.4KeV FWHM

Fluorescence photons are included in charge sum if their deposition takes place within the volume of the pixels neighbouring the initial deposition

-28- 28

Medipix3RX electrical characterization: measurements obtained (chip with sensor)

*Measurements with CdTe, 2mm thick at 110mm pitch (paralizable model fit)

SPM CSM Units

Gain (SHGM) 25 55 e-/DAC step

ENC (SHGM) 75 150 e- r.m.s.

Threshold dispersion (SHGM) 37.5 85.5 e- r.m.s.

Peaking time 120 120 ns

Power consumption 0.78 1 W/chip

Dead time/channel* 0.22/4.5 2.94/0.34 ms/MHz

Count rate*

375 28 Mc/mm2s

37.5 2.8 Gc/cm2s

-29- 29

How imaging can benefit from the Medipix3

architecture:Energy weighting

-30- 30

Energy selective, planar imagingMPX3 CdTe 1mm - Spectroscopic Mode

110µm

23-50 keV14-23 keV9-14 keV

Piezo Lighter

Magnification: 1.3x

Bias: -320V

MPX3 CdTe 1mmColor Mode 4x11 tiles

1 acquisition, 4 thresholds

Courtesy S. Procz

RGB: 9-50 keV

-31- 31

How imaging can benefit from the Medipix3

architecture:K-edge imaging

-32- 32

CT of a phantom0.15s acquisition720 projections

CT scan of a sample containing gadolinium and iodine

Hounsfield units:

water

waterXHU

1000

-33- 33

Mass attenuation for different energies: The K-edge for gadolinium is seen in the CSM

Courtesy, T. Koenig, KIT

-34- 34

The SNR in CSM is better for high energy photons

Courtesy, T. Koenig, KIT

-35- 35

Lessons learnt from the development of the Medipix3.0

-36- 36

Lessons for hybrid pixel detectors designs

• Medipix3.0 was the first large scale mixed-mode chip in 0.13mm in the HEP community

• The biasing circuitry in big area chips is susceptible to thin gate oxide damage during processing if the transistors are not protected by tie-down diodes (in spite of being within antenna rules)

MITHN0.8/10.94

m=10

Bit[0..7]

MITHN MITHN MITHN

MITHN MITHN MITHN

MITHN MITHN MITHN

[1,1] [2,1] [256,1]

c

[1,2] [2,2] [256,2]

[1,256] [2,256] [256,256]

BiasTHN

PIXEL MATRIX

CHIP PERIPHERY

THN control DAC I[1,2]

I[1,256]

I[1,1]

I[2,2]

I[2,256]

I[2,1]

I[256,256]

I[256,2]

I[256,1]

Lack of protection can generate increased VT mismatch and gate current random telegraphic noise

-37- 37

Lessons for Hybrid pixel detectors

• Layout has to be optimized using best layout practices:– Placement of dummy transistors for having equal surroundings for matched

transistors – Placement of matched devices symmetrical wrt Nwell edges– Segmentation of transistors in the length dimension1

– Placement of symmetrical identical metal coverage on top of matched transistors

1“Methodology to evaluate long channel matching deterioration and effects of transistor segmentation on Mosfet matching” H. Tuinhout et al. 2010 Int. conference on Microelectronic test structures, Hiroshima, Japan

-38- 38

Medipix1 (1998)

Medipix2 (2001)

Timepix (2006)

Medipix3 (2009)

Dosepix (2011)

Timepix3 (2013)

Velopix



















-39- 39

Dosepix

• Developed in the framework of the Medipix2 collaboration

• Main application: photon dosimetry

• 16x16 pixel matrix, 220x220mm2 pixels• CMOS 0.13mm technology• 15mW full chip consumption• 1 global analog threshold

• Operation Modes:• Energy binning mode

• ToT measurement @100MHz (12 bit)• Event is energy binned (16 energy

bins, 16x16bit counters)• Rolling Shutter

• Photon counting mode (8 bits)

• Integral ToT (24 bits)

W.S.Wong et al., Electrical measurements of a multi-mode hybrid pixel detector ASIC for radiation detection, JINST 7, 2012. doi:10.1088/1748-0221/7/01/C01056

-40- 40

Dosepix

W.S.Wong et al., Electrical measurements of a multi-mode hybrid pixel detector ASIC for radiation detection, JINST 7, 2012. doi:10.1088/1748-0221/7/01/C01056

Thr

time

vOUTpreamp

Time-over-Threshold

• Developed in the framework of the Medipix2 collaboration

• Main application: photon dosimetry

• 16x16 pixel matrix, 220x220mm2 pixels• CMOS 0.13mm technology• 15mW full chip consumption• 1 global analog threshold

• Operation Modes:• Energy binning mode

• ToT measurement @100MHz (12 bit)• Event is energy binned (16 energy

bins, 16x16bit counters)• Rolling Shutter

• Photon counting mode (8 bits)

• Integral ToT (24 bits)

-41- 41W. Wong

Dosepix single acquisition unprocessed data

Cu

Pd

-42- 42

241Am (59.5 keV)

Cu fluorescence (~8 keV)

Dosepix single acquisition unprocessed data

The (digital) energy thresholds are programmable at a pixel levelThis allows to have multiple bins per measurement

-43- 43

Medipix1 (1998)

Medipix2 (2001)

Timepix (2006)

Medipix3 (2009)

Dosepix (2011)

Timepix3 (2013)

Velopix



















-44- 44

Timepix3 chip

• Developed in the framework of the Medipix3 collaboration (design effort between CERN, Bonn university and Nikhef)

• Applications: Particle tracking by time stamping and measurement of the total deposited charge (e.g. Radiation and beam monitors, dosimetry, gas detectors, HEP TPC readout, HEP prototype for vertex detector)

• 256x256 pixel matrix, 55x55mm2 pixels• CMOS 0.13mm technology

• Simultaneous measurement of ToA and ToT per event (48bits/event) • Packet-based data-driven readout (small readout associated dead time of

375ns)• Maximum dead time free hit rate of 40 106 hits/s/cm2 • Programmable shutdown/wake-up feature for the front-end (analog domain)

and/or general clock gating (digital domain)• Maximum output data bandwidth of 5.12Gbps

-45- 45

Timepix3 Readout

Readout Mode Description

ToA & ToT Fast Time (4b @ 640MHz)ToA (14b @ 40MHz)ToT (10b @ 40MHz)Pixel coordinates (16b)

ToA only Fast Time (4b @ 640MHz)ToA (14b @ 40MHz)Pixel coordinates (16b)

Event Count & Integral ToT Event count (10b)Integral ToT (14b @ 40MHz)Pixel coordinates (16b)

-46- 46

Thrtime

Fine time measurement

Clock (40MHz)

DiscOUT

PreampOUT

Ring oscillator (640MHz)

Fast time counter

-47- 47

Chip electrical characterization ongoing

Chip characterization is ongoing with very encouraging results

-48- 48

Medipix1 (1998)

Medipix2 (2001)

Timepix (2006)

Medipix3 (2009)

Dosepix (2011)

Timepix3 (2013)

Velopix



















-49- 49

Velopix (under design)

• Developed in collaboration CERN and Nikhef

• Velopix has many common features with Timepix3

• Velopix is designed specifically for the upgrade of LHCb VELO (installation during LS2 2018)

• Complete detector is read out for every bunch crossing

LHCB vertex locator upgrade drawing26 sensor planes, 5mm from beam (24 chips/sensor plane)

-50- 50

Timepix3 Velopix Pixel size 55 mm x 55 mm 55 mm x 55 mmPixel matrix 256x256 256x256Chip size 14mm x 16.2mm 14 mm x ~16 mm Input charge e- and h+ Optimized for e-

Leakage current compensation

-5nA (e-), +20nA (h+) 20 nA (e-)

Input referred noise (ENC) ~70 e- r.m.s. (Preliminary results) ~100 e- r.m.s. Minimum threshold, full chip 500e- 500 e-Timewalk <25ns (for Q>1ke and Th=500e-) < 25 ns for 1 ke-Preamp fast reset No Yes (Dead time reduction)Time of Arrival Global Time stamp (25ns), 14 bits

Accurate time stamp (1.56ns), 4 bitsGlobal Time stamp (25ns), 9/10 bits (TBD)

Time over Threshold 10bits To be determined

Average max. hit rate 40Mhits/cm2/s ~300Mhits/cm2/s (average), ~440Mhits/cm2/s (peak)

System clock frequency 40MHz 40 MHzOutput data format Data-driven, zero-suppressed,

Sequential readout availableData-driven, zero-suppressed, grouping of hits to reduce bandwidth (superpixel concept)

Data output Up to 8 SLVS outputs up to 640MHz each

4 GBT links (5.12 Gbps/link x 4 links)

Radiation hardness > 400 MRad > 400 MRadSEU protection No Yes Slow control Custom protocol Compatible with LHCb ECS

Power pulsing features Yes No

-51- 51

Medipix1 (1998)

Medipix2 (2001)

Timepix (2006)

Medipix3 (2009)

Dosepix (2011)

Timepix3 (2013)

Velopix



















-52- 52

Smallpix (under study)

• Developed in the framework of the Medipix3 collaboration• Applications: Particle tracking by time stamping and total deposited

charge measurement (e.g. Radiation and beam monitors, dosimetry, neutron imaging)

• 512x512 pixel matrix, ~40x40mm2 pixels• CMOS 0.13mm technology

• Simultaneous measurement of ToA + ToT1 or PC + iToT • Frame based readout with zero compression (on-pixel and per-

column)• Fast OR• Shutdown/wake-up feature for the front end• 4 side buttable design using Through Silicon Via technology

• The Medipix3 and Timepix3 chips contain TSV landing pads to increase the active area wrt the total chip area but are not designed to be tiled on 4 sides

-53- 53

TSV processing on the Medipix3RX

MEDIPIX3 pixel side native thickness TSV processed chip“BGA” bottom

distribution

• Through Silicon Via is a vertical electrical connection passing through a silicon wafer

• This eliminates the need for wirebonds

J. Alozy(Active area)/(Total die area) with wire bond connections 88.6%(Active area)/(Total die area) TSV connections 94.3%

-54- 54

14.1mm

0.8mm1mm pixel column control circuit

chip configuration logicanalog circuitry (Bandgap, DACs)

I/O logic

14.1mm

Active area wire bond connections 88.6%Active area TSV connections 94.3%

Medipix3 “classical 3-side buttable” architecture

-55- 55

pixe

l col

umn

cont

rol c

ircui

t

chip configuration logic anal

og c

ircui

try

(Ban

dgap

, DA

Cs)

Target Active area TSV connections ~100%Chip can be tiled on 4 sides

Smallpix architecture

-56- 56

Medipix1 (1998)

Medipix2 (2001)

Timepix (2006)

Medipix3 (2009)

Dosepix (2011)

Timepix3 (2013)

Velopix



















-57- 57

CLICpix prototype

Designed in collaboration with the CERN Linear Collider Detector group

ASIC in 65nm CMOS technology designed to fulfill the specifications for the future CLIC vertex detector

• 25x25 mm2 pixel, 64x64 pixel matrix• Simultaneous 4-bit ToA (@100MHz) and 4-bit TOT

measurement• Frame based with zero compression• Power pulsing

Preliminary characterization on the 65nm CMOS technology for radiation hardness showed encouraging results

P. Valerio “A prototype hybrid pixel detector ASIC for the CLIC experiment”1.85mm

3m

m

-58- 58

Summary and conclusions

-59- 59

Summary and conclusions

• The chips designed at CERN in the framework of the Medipix3 collaboration have been presented

• Medipix3 architecture is designed to avoid distortion in the energy spectrum due to charge sharing and fluorescence photons at high spatial resolution (55mm pixel pitch, 75e- r.m.s. noise, ~40 e- r.m.s. dispersion after threshold equalization, 120ns shaping time)

• Dosepix is a real time pixellated spectrometer, 16 on-pixel programmable energy bins

• Timepix3 is the first data driven, simultaneous TOT-TOA measurement in the family. The measurement results are very encouraging.

• Clicpix is the first hybrid pixel detector readout chip of the family in the 65nm CMOS technology (25mm pixel pitch, ~65e- r.m.s. noise, ~22 e- r.m.s. dispersion after threshold equalization)

• Velopix (under design) is being built on the know how acquired by the group in the design of the Timepix3 chip

• Smallpix (under study) will be designed for 4 side buttability

-60- 60

Acknowledgements: Medipix 2/3 collaborations

www.cern.ch/medipix

Medipix2 collaboration memberMedipix3 collaboration memberMedipix2 and 3 collaboration member

-61- 61

Thanks for your attention!

• The chips designed at CERN in the framework of the Medipix3 collaboration have been presented

• Medipix3 architecture is designed to avoid distortion in the energy spectrum due to charge sharing and fluorescence photons at high spatial resolution (55mm pixel pitch, 75e- r.m.s. noise, ~40 e- r.m.s. eq. th. dispersion, 120ns shaping time)

• Dosepix is a real time pixellated spectrometer, 16 on-pixel programmable energy bins

• Timepix3 is the first data driven, simultaneous ToT-ToA measurement in the family. The measurement results are very encouraging.

• Clicpix is the first hybrid pixel detector readout chip of the family in the 65nm CMOS technology (25mm pixel pitch, ~65e- r.m.s. noise, ~22 e- r.m.s. eq. th. dispersion)

• Velopix (under design) is being built on the know how acquired by the group in the design of the timepix3 chip

• Smallpix (under study) will be designed for 4 side buttability

Chips developed at CERN in the framework of the Medipix3 Collaboration

Documents

Transcript of Chips developed at CERN in the framework of the Medipix3 Collaboration