A new incremental ADC (IADC) is proposed which extends the order of a conventional incremental ADC from N to (2N - 1) by way of a two-step operation. For a given conversion time, the duration of each step can be optimised. For an Nth-order IADC, the performance is equivalent to that of a (2N - 1)-order converter. However, it only needs the same circuitry as the Nth-order one. The new IADC is hence more accurate, and also much more power-efficient than the conventional ones.