1. A method of processing input signal data using a look-ahead delta sigma modulator of depth N using natural and pattern loop filter responses, wherein N is greater than or equal to two, the method comprising: determining a set of forced pattern responses of a loop filter of the look-ahead delta sigma modulator to a set of vectors; determining a natural response of the loop filter of the look-ahead delta sigma modulator to a set of input data signal samples; and quantizing each input signal data sample by applying predetermined decision criteria to determine a best match between each forced pattern response and the natural response and selecting output data from an output candidate vector associated with the forced pattern response used to determine the best match.