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Designing analog LSI also by ourselves
Takefumi Mitani1,2, T. Tanaka1,2, Y. Kobayashi1,2, H. Inoue1,2, K. Nakazawa1, T. Takahashi1,2, H.Tajima3, Y. Fukazawa4, S. Uno4, M. Nomachi5, H. Nakamura5, Y. Kuroda6, M. Onishi6
30cm
10cm
High resolution CdTe imaging devices for a Semiconductor Multi-Compton Telescope
High energyFine positionHigh timing
For high sensitivity with SMCT,
1024ch CdTe Array detector for balloon-borne,satellite-borne experiments
High performance of the combination ofanalog LSI “VA32TA” + CdTe pixel
Absorber
Scatterer
FEC control, A/Dconversion andconstruct datapackets
Data acquisitionsystem
Semiconductor Multi-Compton Telescope ( SMCT )
resolution are essential1.
To realize SMCT, we are developing three new technologies
We have developed a low noise analog LSI, “VA32TA” 2, andcombined it with CdTe pixel detector.
Preamp and 2 shapers, one for Spectroscopy and one for self trigger
Serial I/O(Space wire)
Two M8 nutsimageobtained with57Co usinghalf of thedetector.
4.9 mm
Bias: 600V
241Am 0oC
Best spectrum
Bias: 600V
ΔE = 1.7keV(FWHM) @ 60keV, 0 oC
¸2003 model (CAST-H01, CAST-T01) 2-dimensional pixel LSI ( spectroscopy and photo counting )
CdTe diode with 2mm square pixels
18mm
1Institute of Space and Astronautical Science, Japan, 2University of Tokyo, Japan, 3SLAC, 4Hiroshima University, 5Osaka University, 6Mitsubishi Heavy Industries Co., Ltd
A new generation of Compton Telescope, based on semiconductor material,is believed to bring a breakthrough in the observation of the gamma-rayuniverse. To realize the Semiconductor Multi-Compton Telescope(SMCT),we have been working on the development of the semiconductor material andthe readout system.
In the Compton Camera, the incident angle of photon is calculated as e.g.
So the energy resolution is the key factor toimprove not only sensitivity to detect gamma-raylines but also the angular resolution.
CdTe diode: has ahigh energyresolution anddetection efficiencyof gamma-ray.See Tanaka’s poster
Low noise analog LSI:to fullly utilizesemiconductor andachieve high energyresolution.
Multi channel readoutsystem: Compact(weight and power)system is required forballoon-bornesatellite-borneexperiments.
VA32TA
32 channel signal processing
7mm
3.4mm ¸Low noise; Front-end MOSFET geometry optimized for small capacitance load.¸Need only 1 bias (adopting internal DACs)¸Variable shaping time (slow shaper: 1-4 μsec, fast shaper: 75nsec or 300nsec)¸Radiation torelant to 20Mrad
Front end card(FEC)
2.5cmTwo VA32TAs are mounted on 1 FEC. A smallnumber of passive component are used for filtering.
FEC and CdTe diode
We obtained uniform 57Co spectra at +20 oC
Using the FECs, we have developed a compact readout systembased on CPLD technology3.The schematic diagram of the readout system is as follows.
CdTe array 16 FECs Readout card(ROC)Interface card(IFC)
1024 individual CdTe detectors.We adopted “edge-on” geometryfor high detection efficiency.
1.2mm
5mm5 mm CdTe has detectionefficiency of 20% at300keV.
Total power: 10W
To establish an OPEN IP for the high performance analog VLSI, weare working on the IN-HOUSE ASIC development at ISAS based on0.35μm rule.
Reference: 1. SPIE 2002 Takahashi et. al, 2. SPIE 2002 Tajima et. al, 3. IEEE 2003 Mitani et. alE-mail: [email protected]
Chargesensitiveamplifier
Peak hold circuitShaping amp
DiscriminatorInput OutputPole-zero
cancellation
Level adapter andtrigger controller
22mm
44mm
¸2002 model (CAST-K01)
†
(0.37 +0.16 ¥ C) / t [keV]
ΔE = 2.5keV(FWHM)on an average @ 122keV +20 oC
Monitor Shaper out
7 channels was notconnected properlyto CdTe pixels.
In the next version, all channels’connection was OK.
Single elementsof 1024-arraydetector
Fan out board
VA32TA