A method of operating an SAR-type analog-to-digital converter to match the
dynamic range of an input voltage signal to be converted with the full
scale range of the converter, the converter including at least one array
of binary weighted capacitors. The method includes the step of obtaining a
digital gain code that represents the ratio between the full scale range
and the dynamic range of the voltage signal to be converted, applying the
voltage signal to be converted to the capacitor array so as to charge with
the voltage signal to be converted only those array capacitors having the
same binary weights as the bits of the gain code that have a selected
binary value, and selectively coupling the capacitors of the array to one
of a first and second predetermined reference voltage terminals according
to an SAR technique, to obtain an output digital code corresponding to the
input voltage signal.
