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AIS Seminar SLAC, 26.10.12
Development of the DEPFET Sensor with Signal Compression: a Large Format X-ray Imager with Mega-Frame Readout Capability for the
European XFEL
SLAC, 26.10.2012
Matteo Porro on behalf of the DSSC Consortium
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AIS Seminar SLAC, 26.10.12
M. Porro1,2, L. Andricek2,3, S. Aschauer8, L. Bombelli4,5, A. Castoldi4,5, G. De Vita1,2, I. Diehl7, F. Erdinger6, S. Facchinetti4,5, C. Fiorini4,5, P. Fischer6, T. Gerlach6, H. Graafsma7, C. Guazzoni4,5, K. Hansen7, H. Hirsemann7, P. Kalavakuru7, A. Kugel6, P. Lechner8, G. Lutz8, M. Manghisoni10, D. Mezza4,5, D. Moch1,2, U. Pietsch9, E. Quartieri10, V. Re10, C. Reckleben7, C. Sandow8, S. Schlee1,2, J. Soldat6, L. Strueder1,2, A. Wassatsch2,3, G. Weidenspointner1,2, C. Wunderer7
1) Max Planck Institut fuer Extraterrestrische Physik, Garching, Germany 2) MPI Halbleiterlabor, Muenchen, Germany 3) Max Planck Institut fuer Physik, Muenchen, Germany 4) Dipartimento di Elettronica e Informazione, Politecnico di Milano, Milano, Italy 5) Sezione di Milano, Italian National Institute of Nuclear Physics (INFN), Milano, Italy 6) Zentrales Institut fr Technische Informatik, Universitaet Heidelberg, Heidelberg, Germany 7) Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany 8) PNSensor GmbH, Muenchen, Germany 9) Fachbereich Physik, Universitaet Siegen, Siegen, Germany
10) Dipartimento di ingegneria industriale, Universit di Bergamo, Bergamo, Italy
DSSC Consortium
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AIS Seminar SLAC, 26.10.12
Introduction
DSSC Concept overview
Requirements and Design Parameters Focal Plane overview Non-linear DEPFET working principle Non-linear system properties Readout ASIC
Main Achievements
System simulation
Conclusions
Outline
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AIS Seminar SLAC, 26.10.12
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AIS Seminar SLAC, 26.10.12
Up to ~2700 bunches in 600 s, repeated 10 times per second producing 100 fs X-ray pulses (~27 000 pulses/second).
max bunch rate: 4.5 MHz
We want to readout 1024 x 1024 pixel
frames every 220 ns
Bunch structure of the European XFEL
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AIS Seminar SLAC, 26.10.12
2D detectors for EuXFEL
Three Detector Developments at the European XFEL (coordinator: M. Kuster)
Adaptive Gain Pixel integrating Pixel Detector Consortium (AGIPD) (Project Leader: H. Graafsma) o DESY o PSI / SLS Villingen o Universitt Hamburg o Universitt Bonn
Large Pixel Detector Consortium (LPD) (Project Leader: M. French)
o Rutherford Appleton Laboratory / STFC o University of Glasgow
DEPFET Sensor with Signal Compression Consortium (DSSC) (Project Leader: M. Porro)
o Max Planck Halbleiterlabor Munich o DESY o Universitt Heidelberg o Politecnico di Milano / INFN o Universit di Bergamo o Universitt Siegen
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AIS Seminar SLAC, 26.10.12
DSSC Design Parameters
Parameter
Energy range op+mized for 0.5 6 keV
Number of pixels 1024 x 1024 Sensor Pixel Shape Hexagonal Sensor Pixel pitch ~ 204 x 236 m2
Dynamic range / pixel / pulse
~5000 ph @ 0.5 keV > 10000 ph @ E1 keV
Resolu+on Single photon detec+on also @ 0.5 keV
Frame rate 0.9-4.5 MHz Stored frames per Macro bunch 640
Opera+ng temperature
-20C op+mum, RT possible
1 Mpixel camera with:
Single photon sensitivity event at 0.5 keV
high-dynamic range (>10000 ph/pixel)
Frame rate up to 4.5 MHz (1 image every 220 ns)
All the properties have to be achieved simultaneously
DSSC will be the first instrument to fulfill this requirement
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AIS Seminar SLAC, 26.10.12
DSSC Overview - Concept
DEPFET Active Pixel Sensor
Readout Concept Fast analog shaping Immediate 8 Bit digitization (9 bit for f 2.2 MHz) In-Pixel SRAM Readout during macro bunch gaps
Power cycling
Focal Plane
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AIS Seminar SLAC, 26.10.12
1024x 1024 pixels
16 ladders/hybrid boards
32 monolithic sensors 128x256 6.3x3 cm2
DEPFET Sensor bump bonded to 8 Readout ASICs (64x64 pixels)
2 DEPFET sensors wire bonded to a hybrid board connected to regulator modules
Dead area: ~15%
x-y Gap
128 x 256 Pixel Sensor
21 c
m (1
024
pixe
ls)
DSSC Overview- Focal Plane Overview
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AIS Seminar SLAC, 26.10.12
DSSC overview ladder module
~3 mm
1-2 mW/pixel peak power (SENSOR+FRONT-END) 1-2 kW peak power
Power cycling about 1/100
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AIS Seminar SLAC, 26.10.12
DSSC DEPFET
4.5 MHz frame rate
Every DEPFET pixel provides detection and amplification with:
Intrinsic low noise due to the small anode capacitance single photon
sensitivity even at 0.5 keV
Signal compression at the sensor level thanks to the special internal
gate topology high dynamic range
Charge collection time ~ 60 ns
Cu layer for bump-bonding allowing
full parallel readout
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AIS Seminar SLAC, 26.10.12
DSSC DEPFET Principle
Standard DEPFET principle
o p-FET on depleted n-bulk
All signal charge collected in poten+al minimum below FET channel "internal gate"
all signal charges cause an equal effect on the FET current
linear I/Qsig characteristics
o reset via ClearFET
o low capacitance & noise
DSSC adaptation
signal charges at high levels also stored under source
less/no effect on FET current
non-linear I/Qsig characteristics
gain curve engineering by dose & geometry of implantations
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AIS Seminar SLAC, 26.10.12
DSSC DEPFET Simulation and Layout
236
m
272 m Pitchx: 204 m Pitchy: 236 m
DEPFET
Dri_ rings
hexagonal shape
- side length 136 m (A=48144 m2)
- compatible with C4 bumping @ IBM
technology
- 2 polySi layers
- 2 + 1 metal layers
- 12 implantations
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AIS Seminar SLAC, 26.10.12
In the linear region the noise is dominated by electronics noise of the sensor and the readout electronics
Single photon detection properties are given by the electronics noise of the system with empty internal gate
For a high input signals more photons fall within one ADC bin. The quantization noise is dominant.
The quantization noise is always below the poisson noise of the photon generation process
Analog to digital conversion single photon detection and quantization noise
Electronics noise ADC bin size
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AIS Seminar SLAC, 26.10.12
Dynamic range
1 ph @1keV Dynamic range for 3keV
ph 8 bits (~8300 ph.)
256 x bin size @3 keV
The achievable dynamic range depends on: The shape of the DEPFET non-linear characteristic The number of bits of the ADC The number of bins of the ADC associated to the signal produced by the first collected photon The photon energy.
The dynamic range increases with the photon energy. This is because as the photon energy increases, the number of photon falling in the low-gain region of the DEPFET response also increases: it is possible to allocate more photons in the same number of bins
Dynamic range for 1keV ph 8 bits (~2400 Ph.)
256 x bin size @1 keV
8 bit 28 bins = 256 bin
Bin size
Bin size
1 bin / ph.
1 ph @3keV
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AIS Seminar SLAC, 26.10.12
Dynamic range
1 ph @1keV Bin size
Dynamic range for 1keV ph 8 bits (~2400 Ph.)
256 x bin size @1 keV
The achievable dynamic range depends on: The shape of the DEPFET non-linear characteris+c The number of bits of the ADC The number of bins of the ADC associated to the signal produced by the first collected photon The photon energy.
The dynamic range increases with the number of bits
1 bin / ph.
Dynamic range for 1keV ph 9 bits (~12080 ph.)
512 x bin size @1 keV
9 bit 29 bins = 512 bin
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AIS Seminar SLAC, 26.10.12
DSSC overview - ASIC
Every ASIC pixel comprises in 206 x 236 m: A trapezoidal analog filter (optimum filter for white series noise) A single slope 8 bit ADC (9 bit for f2.2 MHz) An SRAM able to store 640 frames
Gain and offset can be adjusted pixel-wise
Single slope ADC ASIC final format : 64 x 64 pixels 130 nm CMOS Process C4 Bumps
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MAIN ACHIEVEMENTS (on sensor and readout ASIC)
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AIS Seminar SLAC, 26.10.12
Sensor - Measured Non-linear 7-cell DEPFET Prototype
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spectroscopy
o Fe55 source
linear region of the gain curve
noise peak ~ 10 el. ENC
Mn-K line ~ 150 eV FWHM @ 5.9 keV
Response to a pulsed laser/electrical charge injection
increasing number of identical pulses
peaks are equidistant in terms of signal charge
signal compression @ large charge amount
"energy" calibration using Fe55 spectrum
non-linear gain of DEPFET prototype
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AIS Seminar SLAC, 26.10.12
non-linear gain DEPFET (pxd-7)
signal compression
o seven cells of a cluster
o standard variant (W/L = 25/3)
o sensitivity in the linear region
gq 600 pA/el.
o compression factor
~ 17.5
o current dispersion
I/I 10 %
non-l
