- Roof Board
- Chip Development
- Prototype boards
- Glossary and Index
The ASTRAL chip was previously referred to as the "ASDDTM" chip.
ASTRAL BiCMOS Integrated Circuit
The bipolar ASDBLR and CMOS DTMROC chips described above demonstrate the performance
necessary for the final TRT, but require a significant mounting area on the detector
(especially in the Barrel case where space is very tight).
The recent commercialisation of the DMILL semiconductor process, however, opens the
possibility of combining the functionality of both devices on a single radiation hard
BiCMOS substrate (ASTRAL).
Several sub-blocks of both the ASDBLR and DTMROC have already been successfully fabricated
and tested in the DMILL process. The remaining technical questions are whether or not the
high sensitivity analogue blocks can safely co-exist with the high speed digital blocks.
While it may not be immediately obvious that there is any reduction of area as a result of
merging the two designs, one can see from Figure 1 that many of the connections
(pads) on each circuit are concerned only with communicating with the other chip.
By eliminating the external input and output pads and the cells required to convert to and
from the low level ternary encoded outputs it is possible to go from three 64 pin packages
(two 8 channel ASDBLR's and one 16 channel DTMROC) to two 48 pin packages if one implements
8 channel in an ASTRAL. This would result in a very significant reduction in board area
required for the on chamber electronics. The possibility to implement 16 channels in one
ASDDTM will also be explored.
It is foreseen to develop during the years 1997 and 1998 first a DMILL version of the
ASDBLR and DTMROC (according to the new specifications), and then the combined ASTRAL.
The goal is to have a first version of the latter before the end of 1998.
Figure 1 Block diagram of ASDBLR-DTMROC interconnections
Text and pictures extracted from Atlas Inner Detector, Technical design Report