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A low-power high dynamic range front-end ASIC for imaging calorimeters. M.G.Bagliesi (a), P.Maestro (a), P.S.Marrocchesi (a), M.Meucci (a), V.Millucci (a), F.Morsani (b), R.Paoletti (a), F.Pilo (a), A.Scribano (a), N.Turini (a), G. Valle (a)
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A low-power high dynamic range front-end ASIC for imaging calorimeters M.G.Bagliesi (a), P.Maestro (a), P.S.Marrocchesi (a), M.Meucci (a), V.Millucci (a), F.Morsani (b), R.Paoletti (a), F.Pilo (a), A.Scribano (a), N.Turini (a), G. Valle (a) (a) Universityof Siena - INFN Gruppo Collegato,Italy (b) Istituto Nazionale di Fisica Nucleare INFN - Pisa, Italy
Scintillator based detectors designed to operate at very high energy (up to the multi-TeV scale) require • high dynamic range • low-noise dedicated front-end electronics with:
charge values ranging from a few tens of fC (for minimum ionizing particles) to several hundreds of pC (for high energy showers) For imaging calorimeters with MAPMT read-out, the high gain of the photodetector at operating conditions results in The idea ! Our group developed a front-end ASIC where each input signal is split into three equal signals and, then, each branch is mirrored with different scaling: 1/1, 1/8 and 1/80. The total number of read-out channels is multiplied by 3
Ahybridwhich houses 12 chip-sets was developed by Ideas ASA (Norway) as a joint project with the University of Siena and INFN. • Eachchip-setconsists of two chips: • ICON_4CH • VA4_PMT • and has the capability to read-out four anodes of a MAPMT. • The hybrid can eventually house12TA-chips(based on the TA32CG architecture, Ideas ASA, Norway) to give trigger capability to the system. • Our read-out system prototype is a board with standard VME interface. • The hybrid is implemented as apiggyback boardplaced on top of this VME-board by means of 100mil pitch double-row header connectors
ICON_4CH VA (+ optional TA) ~10 cm
ICON_4CH • The ICON_4CH has4 inputs • Input signals aresplit into three equal signalsby a current conveyer • Each branch mirrors the input withdifferent scaling: 1/1, 1/8 and 1/80 and is linear for input charge values below ~120 pC, ~1050 pC and ~4250 pC respectively • Since each mirrored signal has its own output pad, this gives12 output pads • Power consumption in quiescent state is ~3.3 mW (~0.83 mW/channel)
VA4_PMT • It is a 12 channelcharge sensitive preamplifier-shaper circuitwith: • low noise (~10 fC), • low power consumption: ~34 mW (~2.8 mW/channels), • high dynamic range (± 32.5 pC), • simultaneous sample-and-hold, • multiplexed analog read-out, • calibration facilities, • programmable gain in the preamplifiers
VA4_PMT ICON_4CH PRINCIPLE OF THE TWO-CHIP STRUCTURE forone input channel of the ICON_4CH Theexternal capacitors (tipical value ~ 1nF) used for AC-coupling are shown in the middle
Hybrid features LOW POWER: power budget ~ 10W for ~ 103 channels Each front-end chipset has about 38 mW power consumption and this means about 450mW for the hybrid. • HIGH DYNAMIC RANGE: 105, range from 102 fC to 103 pC • CURRENT CONVEYOR (split + mirror) • TRIPLE RANGE
MINIMAL CROSS-TALK: 0.1% for input charge values below 100pC, 0.1-0.3% above • ASIC-PMT DISTANCE: • the board is connected to the PMT anodes through standard • 50 ohm coaxial cables • ==> The electronics can be located far away from the PMT • ==> minimum number of cables: signals + PMT power supply • ==> a lot of possibilities of implementation, e.g.: crate modules or stand-alone board.
FAULT TOLERANCE: • HYBRID BOARD: • chip control lines are separated, • no daisy-chains • VME READ-OUT BOARD: • one ADC for each VA chip, • ADC control lines are separated
POSSIBLE ADDITIONAL FEATURES: • to give trigger capability to the system, a modified TA chip (from TA32CG architecture) has been specified to: • provide an analog output signal proportional to the number of input channels above a programmable threshold; • provide an analog output signal proportional to the sum of 4 analog inputs (they can be chosen among the available 12 channels from the Icon chip when the die is mounted on the hybrid: this allows additional flexibility in the choice of the dynamic sub-range to be used for triggering purposes).
Example of application: Trigger in Calorimeters Hadron Event EM Event
Our lab Hybrid on top of VME read-out board
Input signal PMT Hybrid Pulse generator Trigger Measurement setup LED
Linearity Tests performed with a R7600-00-M4 PMT
Noise S/N ratio for a MIP of 0.8 pC: ~ 16 • Noise can be reduced in a future development by: • decreasing the number of ranges from 3 to 2 for the ICON • fixing the gain in the preamplifiers for the VA4
Cross-talk for R7600-00-M4 PMT is ~ 0.5% Cross-talk
Immediate applications: New generation space-based or balloon-borne experiments for the study of high energy primary cosmic rays (e.g.: AMS-02, CALET, CREAM, ... )
Summary • LOW POWER CONSUMPTION:~ 450mW • HIGH DYNAMIC RANGE:~105, from 102 fC to 103 pC • MINIMAL CROSS-TALK: less then 0.3% • BOARD-PMT DISTANCE • FAULT TOLERANCE