What, in simple terms, is
the benefit of the KD1S topology?
Since 1-bit quantizers are used the transistor matching can be
horrible.
Even the minor effects of
the Kpath comparator’s
offsets can be reduced
by adding a single pre-amp on the output of the integrator. It’s
possible
to attain > 40 dB SNR (> 6-bits) with matching approaching 50
% (e.g.,
one transistors threshold at 100 mV while another’s at 200 mV). This
is
possible without calibrations or additional overhead. Considerably larger
SNRs can be achieved at the
cost of conversion bandwidth.
While the KD1S’s tolerance
to mismatches will clearly become more
important as CMOS technology marches toward the sub-10 nm nodes,
other benefits include: 1) the natural way the KD1S interfaces with
software for ease of changing the ADC’s characteristics, 2) the higher-
sampling frequency, 3) it’s small and low power, and 4) the design is
easy to move between process
nodes.