A method and apparatus for system offset calibration using an overranging
ADC is provided. The overranging ADC is configured to convert an analog
signal into an intermediary digital signal. The conversion range of the
overranging ADC is extended beyond the full dynamic range of the ADC
system. The intermediary digital signal has more bits than the digital
output signal. A digital fine offset adjustment circuit is configured to
provide the digital output signal by digitally subtracting a fine offset
from the intermediary digital signal and decoding the intermediary digital
signal. The digital output signal has approximately no offset, and has
approximately no loss in dynamic range.
