Patent ID: 7157945

Claim:
A method of providing a window comparator function with a single comparator unit that has a positive input (c p ), a differential negative input c n and an output (c out ), wherein limits of a window are defined by a reference voltage (V ref ) and a window condition is defined for a differential voltage between a positive input voltage (V inp ) and a negative input voltage (V inn ) so that the differential voltage is within the limits of the window, comprising the steps of: a) providing a common mode voltage (V mid ); b) providing a first set of two switched capacitors (C 1p , C 2p ) each of which has a first electrode connected to the positive input (c p ) of the comparator unit; c) providing a second set of two switched capacitors (C 1n , C 2n ) each of which has a first electrode connected to the negative input (c n ) of the comparator unit; d) providing a switching array capable of assuming a plurality of different switching conditions; e) switching the second electrodes of the capacitors (C 1p , C 2p ) in the first set selectively between the positive input voltage (V inp ), the reference voltage (V ref ) and zero voltage potential (0V); f) switching the second electrodes of the capacitors (C 1n , C 2n ) in the second set selectively between the negative input voltage (V inn ) and zero voltage (0V); and g) detecting the output (c out ) of the comparator unit in relation to the switching condition of the switching array.