Comparator
ASIC "COMP-A" (1997)
In Spring '97, six 8-channel "COMP-A" comparator ASICs (48 channels total)
designed by J.C. Santiard were installed and tested at a CERN test beam
with the P0' cathode strip chamber prototype and recent OSU "Buckeye" preamp
chips. These ASICs, having 144 outputs (center, left, and right for each
strip), were mounted on a small mezzanine card which plugged into a custom
CAMAC latch module. The mezzanine card and latch module were made by UCLA.
Due to a fire in the PS accelerator, beam time was extremely limited
at CERN. Because of comparator ASIC offsets, performance was degraded during
this time. After the fire, post-amps with gains of first 2.5 and later
4 were introduced to reduce the effect of offsets. Unfortunately, there
was no beam at this time, and cosmic ray events were not clean, probably
because no iron or lead filter was used.
48-Channel Comparator Mezzanine Cards
These surface-mount cards were built at UCLA by Yao Shi. They are stuffed
with many discrete components, which are mounted on both sides of the cards,
which serve the 6 comparator ASICs from Jean-Claude Santiard of CERN. The
comparator ASICs are socketed. The boards have low-density input connectors
and high-density output connectors to the CAMAC board below. There has
been absolutely no trouble with the mezzanine cards. Here is a picture
of the Comparator Mezzanine Card - note the six ASICs mounted with their
discrete components:
48-Channel Comparator Latch Cards with CAMAC Readout
These boards, built at UCLA by JK, contain latches and a CAMAC interface.
There are 144 latch bits (left, right, and center for each strip). They
performed flawlessly. Here is a picture of the Comparator Latch card together
with the Comparator Mezzanine card:
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Page maintained by
Jay Hauser (hauser@physics.ucla.edu)
last updated 22 June 1999