May 15, 2001,
Gerald Przybylski, Lawrence Berkeley National Laboratory
 

Updates to apply to the AMANDA Digital Optical Module for use by IceCube

The deployment of the first generation production DOM into AMANDA string 18 in the 1999-2000 astral summer season proved very informative.  Many elements of the design proved quite successful, however, knowledge gained from the experience suggests areas for redesign.
 
 
Element to address Reason
PMT base control via serial port instead of analog voltage Eliminate the sharing of the power return ground with the ground used for voltage control.  Improve accuracy.
30 MSPS ADC Replacement Analog Devices now lists the part as obsolete
3.3 and 2.5 V power supply redesign New dual supply part will help reduce part count and increase reliability
+/- 5V power supply redesign Improve efficiency, and allow input up to 100 VDC. This cuts down on IR losses in the twisted quad
MUX replacement in front end Substitute lower power parts now available.
Change ATWD footprint to one for a smaller 64 pin package Save space and improve routability
Update memory layouts for denser chips. Save power and improve reliability by reducing net trace count on the board.
Change layer stickup for digital noise reduction Better engineering practices
Alter FPGA pin-out to accommodate possible migration to FPGA with hard core ARM CPU integrated in same package Reduce dependence on Cirrus Logic as a part supplier. (We live in interesting {volatile} times)
Change PLD pin-out to enhance utilization of resources More functionality from the chip.
Neighbor signaling modifications Better to accommodate next nearest neighbor local coincidence notification.
Redesign cable front end for the impedance of the new cable Proper use of resources
Use new faster, lower power, minimal power transient comparators for PMT signal triggering Good engineering
Differential signaling of PMT triggers across a split ground Good engineering
Design communications front end for duplex communications Eliminate slow recovery of saturating amplifiers in data signaling path.
Delete the interface for analog fiber driver. Dropped from system master plan
Incorporate an interface for digital fiber data transmission Possible support for IceTop


The list above is preliminary, but fairly complete. 
Suggestions are invited.  Send email to