1. A method of processing a signal using a multiple output infinite impulse response (“IIR”) filter of a look-ahead delta-sigma modulator, the method comprising: determining a set of state variables for respective stages of the IIR filter for a time t from a set of input signals, wherein at least a subset of the state variables of the respective stages of the IIR filter represent a current response and at least one future response elements of a natural response vector of the IIR filter, wherein t represents a time index value; and determining a quantization output of the look-ahead delta sigma modulator for the time t using the natural response vector determined for the time t.