Patent ID: 7088779

Claim:
A method for reducing the number of bits of a digital input signal, said method comprising the steps of: adding a pseudo-random noise signal to the digital input signal to form an intermediate signal, the pseudo-random noise signal being defined by noise parameters; and quantizing the intermediate signal having a word length of n bits to a reduced word-length signal having a word length of m bits, where n and m are integers, n being larger than or equal to m, the quantizing of the intermediate signal including a first transfer function which is non-linear, the first transfer function being defined by non-linear device parameters, a quantization step of the first transfer function for small amplitudes being smaller than a quantization step for large amplitudes, wherein the gain of the first transfer function is substantially equal to one for small amplitudes, and wherein the gain decreases for large amplitudes, and wherein the first transfer function equals: M e /D i =c 1 tan h ( c 2 D i +c 3 ), in which M e is the reduced word-length signal, D i is the intermediate signal, and c 1 , c 2 , c 3 are the non-linear device parameters.