  Searches for radio signatures of ultra-high energy neutrinos and cosmic rays
could benefit from improved efficiency by using real-time beamforming or
correlation triggering. For missions with power limitations, such as the
ANITA-3 Antarctic balloon experiment, full speed high resolution digitization
of incoming signals is not practical. To this end, the University of Hawaii has
developed the Realtime Independent Three-bit Converter (RITC), a 3-channel,
3-bit, streaming analog-to-digital converter implemented in the IBM-8RF 0.13 um
process. RITC is primarily designed to digitize broadband radio signals
produced by the Askaryan effect, and thus targets an analog bandwidth of >1
GHz, with a sample-and-hold architecture capable of storing up to 2.6
gigasamples-per-second. An array of flash analog-to-digital converters perform
3-bit conversion of sets of stored samples while acquisition continues
elsewhere in the sampling array. A serial interface is provided to access an
array of on chip digital-to-analog converters that control the digitization
thresholds for each channel as well as the overall sampling rate. Demultiplexed
conversion outputs are read out simultaneously for each channel via a set of 36
LVDS links, each running at 650 Mb/s. We briefly describe the design
architecture of RITC. Evaluation of the RITC is currently under way, and we
will report testing updates as they become available, including prospects for
the use of this architecture as the analog half of a novel triggering system
for the ANITA-3 ultra-high energy neutrino experiment.
