Simultaneous Photon Counting and Charge Integrating Readout Electronics for X-ray Imaging Hans Krüger, University of Bonn, Germany. University of Bonn: Michael Karagounis, Manuel Koch, Edgar Kraft, Hans Krüger, Norbert Wermes University of Mannheim: Peter Fischer, Ivan Peric
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Simultaneous Photon Counting and Charge Integrating Readout Electronics for X-ray Imaging Hans Krüger, University of Bonn, Germany
University of Bonn: Michael Karagounis, Manuel Koch, Edgar Kraft, Hans Krüger, Norbert Wermes University of Mannheim: Peter Fischer, Ivan Peric
Philips Research Laboratories Aachen: Christoph Herrmann, Augusto Nascetti, Michael Overdick, Walter Rütten
Hans Krüger, University of Bonn
more information from the same x-ray dosage
Integrator
Photon counter
signal intensity
Hans Krüger, University of Bonn
Conversion Layer
Total deposited energy
Mean photon
energy
Integrating Channel
Counting Channel
Number of
absorbed photons
Preamp
Hans Krüger, University of Bonn
Hans Krüger, University of Bonn
chip features:
Hans Krüger, University of Bonn
Hans Krüger, University of Bonn
UCINT
Time320µs
small current
t
UCINT
Time(1/3)*320µs
larger current
t
Frame=320µs
fclk = 8 MHz
pump cycles = 2
Time = 2560
Imeas[pkts./clk] = 1/2560
= 0,0004
fclk = 8 MHz
pump cycles = 2
Time = 853
Imeas[pkts./clk] = 1/853
= 0,0012
Hans Krüger, University of Bonn
leakage current compensation
(slow)
feedback
(fast)
Hans Krüger, University of Bonn
Hans Krüger, University of Bonn
Hans Krüger, University of Bonn
Ibias
in
in
out
out
Iload
Load
I U
Load
I U
Ibias
½ Ibias
Vlo
Vhi
Vload
'ideal' load characteristic
CML principle (inverter)
P. Fischer, E. Kraft, “Low swing differential logic for mixed signal applications”, Nucl. Instr. Meth. A 518 (2004) 511-514
Hans Krüger, University of Bonn
in
bias
VSS
GND
Load
I U
measured load characteristic
Iload
½ Ibias
Vlo
Vhi
Vload
Hans Krüger, University of Bonn
Hans Krüger, University of Bonn
Hans Krüger, University of Bonn
discretisation limit
perfect
12-bit ADC
Poisson SNR limit
Hans Krüger, University of Bonn
DIRECT injection
via feedback
Poisson SNR limit
Hans Krüger, University of Bonn
200 nA
integrator
12 nA
6 MHz max.
pulse frequency
overlap region
66 pA
photon counter
a single pulse
3 pA
Hans Krüger, University of Bonn
photon counter
overload
original pulse size
integrator lower limit
total energy / photon count
Hans Krüger, University of Bonn
Hans Krüger, University of Bonn