The next-generation very-high-energy (VHE) gamma-ray observatory, the
Cherenkov Telescope Array, will feature dozens of imaging atmospheric Cherenkov
telescopes (IACTs), each with thousands of pixels of photo-sensors. To be
affordable and reliable, reading out such a mega-channel array requires event
recording technology that is highly integrated and modular, with a low cost per
channel. We present the design and performance of a chip targeted to this
application: the TeV Array Readout with GSa/s sampling and Event Trigger
(TARGET). This application-specific integrated circuit (ASIC) has 16 parallel
input channels, a 4096-sample buffer for each channel, adjustable input
termination, self-trigger functionality, and tight window-selected readout. We
report the performance of TARGET in terms of sampling frequency, power
consumption, dynamic range, current-mode gain, analog bandwidth, and cross
talk. The large number of channels per chip allows a low cost per channel (\10
to \20 including front-end and back-end electronics but not including
photosensors) to be achieved with a TARGET-based IACT readout system. In
addition to basic performance parameters of the TARGET chip itself, we present
a camera module prototype as well as a second-generation chip (TARGET~2), both
of which have been produced.Comment: 16 pages, 15 figures, version 3 (matches version published in
Astroparticle Physics
