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To further reduce the offset, the modulator is chopped at
system-level. A chopper switch at the input and a switch at the
output periodically reverse the polarity of the input signal and
the bitstream. To avoid disturbing the operation of the modulator when chopping, its state is also inverted by swapping
the integration capacitors of both integrators. The chopping is
done at a slow speed to make errors due to charge-injection
in the chopper switches negligible.