Patent ID: 7583213

Claim:
A signal processing system for changing a level of an input signal to generate an output signal, the signal processing system comprising: an up-sampling circuit, for performing up-sampling to generate the input signal; a shifter for receiving the input signal and for bit-shifting the input signal according to a first predetermined gain to generate a first adjustment signal; a delta-sigma modulator, for generating the output signal according to a second adjustment signal and the first adjustment signal; and a level adjuster, for receiving the output signal and adjusting a level of the output signal according to a second predetermined gain to thereby generate the second adjustment signal to the delta-sigma modulator; wherein the level adjuster comprises: a lookup table for storing a relationship between all combinations of possible second predetermined gains, possible output signals, and corresponding second adjustment signals; and a converting module for receiving the output signal and the second predetermined gain, and outputting the second adjustment signal by checking the lookup table according to the received output signal and the received second predetermined gain in order to output the second adjustment signal stored in the lookup table that corresponds to the combination of the received output signal and the received second predetermined gain.