Summary of experiences with the ALTRO electronics -Excellentnoise, ca 350 electrons on one FEC connected to chamber -Routineoperation of 10000ch with commonthreshold at 4 adcchannels ( ca 2000 electrons). • Problems • -Breakingamplifierchannels • -cooling, verticalFECs, convectionsufficient • cooling horisontal FECs, needsforced air cooling . Not a practical • solution for the future
Broken channelsdue to dischargesin the GEM system Happenstoofrequently May in the worstcasekill a FEC i.e 128ch. Has to be solved Haveemulatedinjection of 20mJ in amplifer input. Kills the internalprotection of the channel with same symptoms as real failure. Externaldiodenetwork as belowworks as protection for emulated input. Will be tested for noise Testing on GEM chamber at next DESY test.
FEC-MCM 8 SALTRO16 128 channels Naked Si wirebonded to board 31.5*23.5mm Topside Connectors to Readout board 4 connectors to pad board Belowside
Back plane LV Voltage regulators FPGA Board CTRL LV&ctrl FEC-MCM Pad panel
6*6 matrix of FEC-MCM. Total 4608 channels, padsize, 1.0*5.9mm On a pad panel.
Advantages of MCM modulecompared to all electronics on the padpanel • trace routing from pads to SALTRO16 becomes simpler - MCM module offers 2 extra layers for components. • electronics prototyping will be cheaper and easier. • parallellprototyping possible • possibility to distributedesign and fabrication -analog and digital functions are well separated, - minimal heat transport to the TPCendplate • service by replacement of MCM module. • simpler endplate construction
But in the prototypestagewherewe are now and a couple of yearsto come wethink that an MCM module with 128channels is toorisky and expensive -Risky as long as the broken channel problem is not under control -Evenifweunderstand this problem, this electronics will be used in tests of variousavalanchechamberprototypes. Thisis a danger in itself. Expensive to replace 128 channelsifone is broken. Expensive to manufacturesince the chip yield is unknown and the chance of assembling 8 workingbutuntested chips on a board may be quitelow. The SALTRO16 is a ratherlarge chip. The yieldcan be as low as s 90% (including bonding). Thenonly 43% of the moduleswill be OK ifthere are 8SALTRO per module As a consequencewethink that mostprototyping has to be made with a smaller MCM module.
MCM with 2 SALTRO Bus card Read&ctrl MCM
1Test Read&ctrl with buscardtogether with RCU. Read small card with PCA16+ALTRO 2 Chip Characterisation 3Beam test old system at DESY. Decisionabout input protection