Abstract: A multi-mode analog to, digital converter (ADC). The novel ADC includes an input terminal for receiving an analog input signal; a plurality of processing stages, each processing stage adapted to generate an output signal from an input to that processing stage; and a mechanism for determining a mode of operation and in accordance therewith connect the processing stages and the input terminal in a predetermined configuration. In an illustrative embodiment, the ADC can be configured as a subranging ADC, and the mechanism for determining, the mode of operation includes a signal processor for automatically selecting the mode of operation based on the frequency components of the input signal.